optional module d Flashcards
1
Q
where is asprin first extracted
A
bark of willow trees
2
Q
how is asprin made now
A
reacting acetic anhydride with saliculic acdid
3
Q
what forms asprin or acetylsalicilic acid
A
salicylic acid and acetic anhydride
4
Q
what is the goal of drug production
A
to minimise costs and maximise profits
5
Q
the drug development proces
A
drug discovery
pre clinical trials
phase I, II and III of clinical trials
review
manufacturing
6
Q
whats an issue with coutnergeit medicines
A
drug purity and the containing of the active drug ingredient
7
Q
what is combinatorial chemistry
A
a laboratory method that involves using robotics to synthesise thousands of different compounds at a time, usually peptides or small molecules. The compounds can then be tested for effectiveness, and then kept for further testing or modification, or discarded. With this highly automated process, large volumes of molecules can be synthesised and tested in a short period of time, but it is more of a trial-and-error approach, resulting in a large amount of molecules made that have no activity. Although it is difficult for scientists to mimic natural processes, combinatorial chemistry is proving to be making new advancements in drug discovery.
8
Q
double blind test
A
Part of the drug development process is to conduct a ‘double blind test’ where a placebo is offered to one group of patients, while the other group receives the drug. A placebo is a pill, lotion or injection that does not contain the active ingredient that the drug has, and is used to see if the drug does have a measurable effect compared to not using the drug. Many times, people taking the placebo report to have improvements in their health, even though they are not taking the actual drug. This “placebo effect” has been noted in numerous studies.
9
Q
a placebo is
A
identical to the trial drug, except it is missing the active drug ingredient under study.
10
Q
Drugs can be administered in a variety of ways including:
A
Ingestion by mouth (e.g. pills or syrups).
Injection with a syringe under the skin into fat or muscle tissue or bloodstream.
Inhalation by mouth or nose (e.g. as with an inhaler or nebuliser).
Absorption through the skin (e.g. medicated lotions or stick-on patches).
Absorption in the rectum or vagina (e.g. suppositories).
Applied into the ear or eye (e.g. drops of prepared solutions).
11
Q
why can all drugs not be adminstered orally
A
Some medicines, however, may irritate the digestive tract or cannot be absorbed by this method and must therefore have another route into the body. Some drugs are best absorbed when applied to the part of the body that is being treated, for example, antibiotic drops for an ear or eye infection.
12
Q
The speed and ability of the body to absorb and use the medicine, known as
A
metabolism
13
Q
what is quicker injectin or oral adminsteration
A
injection. Some drugs are best employed with a quick absorption of the entire dose, such as with an insulin injection when treating diabetes, while others are more effective when absorbed slowly over time, such as the hormones used in birth control skin patches.
14
Q
what determines form of administeration
A
dosage of drug
freq of adminsteration needed
tolerance of drug
potential for addiction
15
Q
how can drug addiciton be deterred
A
A slower, time-released method, such as with oral ingestion or a skin patch, can help to keep the levels of medicine in the body lower and more consistent, and avoid dependency.
16
Q
where is the drug aiming
A
the target site
17
Q
how do drus that have an effect on specific types of cells do
A
The target cells are identified by three-dimensional receptors into which the drug fits like a key in a lock. If the drug passes by cells that do not contain the receptor, it will not bind to the cell and have a medicinal effect.
18
Q
bioavailability
A
the fraction of the administered dosage that reaches the target site.
19
Q
what is the only method of administeration that is 100% bioavailability
A
intravenous
20
Q
risks of oral administeration
A
irritation of digestive tract
drug maybe destroyed by stomach acidity
absorbed by bacteria in small intestine
21
Q
different types of injection
A
intramuscular
subcutaneous
intravenous
22
Q
which layer does intravenous enter
A
dermis under epidermis`
23
Q
how can polarity affect bioavailability
A
Since the drug must eventually reach the blood, which is polar as it has a water solvent, the drug must have some polarity, since “like dissolves like”. For the drug to enter the cell, it must also have some nonpolarity to pass through the cell membrane. Therefore, drugs must have both polar and nonpolar properties.
24
Q
what functional groups must drugs have to be absorbed
A
Drugs must have both polar and nonpolar functional groups to be absorbed by the body and at the cellular level.
25
polar functional groups include
hydroxyl, carboxyl or amino groups
26
why are some drugs to be taken either with food or on an empty stomach
If the drug is administered orally (usually with a sip of water), then a polar drug will generally dissolve within the polar environment of the contents of the stomach. If the drug is not very polar, it might bind to food particles instead, preventing it from being absorbed.
27
State factors that can affect the ability of the body to absorb a drug.
Age
Weight
Gender
Method of administration
administration
weight
mass
polarity
Polarity
functional group
functional groups
solubility
stomach contents
28
how does age affect bioavailability
as the body ages, its chemical processes change, thus possibly increasing or decreasing the rate the body can absorb a medicine.
29
how does weight affect bioavailability
generally a greater body mass requires a higher dose to keep the concentration at a level that has a medicinal effect.
30
What is meant by the term 'drug tolerance'?
A decreased effect of the drug on the body when taken over a long period of time.
31
Medicines can target specific cells in the body, which are identified by
receptors on the cell membrane.
32
therapeutic window
where the drug is effective is
33
the effective dose
where it has a effect in 50% of the population
34
what is the lethal dose
where it kills half the population
35
toxic dose
where a serious toxic effect is observed for half the epopulation
36
ED50 -
the minimal effective dose for 50% of the population (animal and human trials).
37
LD50 -
the lethal dose for 50% of the population (animal trials).
38
TD50 -
the toxic dose for 50% of the population (human trials).
39
theraputic indexes for animal and human studies
therapeutic index=LD50/ED50 (for animal studies)
therapeutic index=TD50/ED50 (for human studies)
40
A medicine with a low therapeutic index would be considered to be...
not safe, but could be used with careful monitoring.
41
For drugs that are available without a prescription, the medicine would usually have...
a high therapeutic index.
42
what reaction takes place to create asprin
an esterification reaction
43
what is required to create asprin
Like for all esterification reactions, heat and a strong acid (H2SO4) are required to catalyse the reaction and ensure a greater product yield.
44
what is the product that will be asprin and ho wis it collected
asprin is white crystals that can be collected by filtration (gravimetric or vacuum filtration) when the mixture cools in an ice bath following the reaction.
45
why shouldnt you use the asprin you make by yourself
it will have low purity and the by-product of acetic acid may be present in your sample, along with salicylic acid and acetic anhydride that may not have reacted if the reaction had not gone to completion. And, of course, a classroom laboratory is hardly a sterile environment!
46
to improve the purity of the product, the asprin crystals are subjected to a
recrystallisation process
47
how does recrystallisation of asprin work
by removing impurities by dissolving them in ethanol, which has polar and nonpolar properties. The impurities will dissolve and be rinsed away with the ethanol/water mixture, leaving behind the pure aspirin crystals, which have a melting point of 136°C, meaning it will become a solid when cooled to room temperature.
48
The process of recrystallisation
49
Recrystallisation is the process of purifying a solid organic product using the following steps:
Add a small amount of a solvent (generally ethanol is used) and place in a hot water bath to dissolve crystals.
Add cold water and/or use an ice bath to lower temperature to crystallisation point of organic product.
Collect solid organic product using filtration (vacuum or gravimetric). Any impurities will remain dissolved and flow through.
50
how to test purity of a sample using mp
use melting point
a pure sample of asprin will melt very close to 136 degrees (melting point range)
An impure sample will have a melting point lower than the theoretical temperature, as impurities disrupt the crystalline structure, weakening the attractive forces between particles. The lower the purity, the greater temperature difference from the theoretical melting point, and the broader the melting point range.
51
how to test for purity using infrared spectroscopy
Infrared spectroscopy (IR) identifies specific types of bonds in a molecule. For aspirin, the types of bonds expected in a pure sample are strong absorption around 1700 cm-1 for the C=O bond in carboxylic acids, and broad absorption around 2800 cm-1 for the O-H bond in carboxylic acids. Using IR is helpful to determine if the sample tested contains the type of bonds (and thus specific functional groups) expected in aspirin, or it might identify the bonds present in the impurities.
52
The melting point of aspirin is 136°C. The presence of impurities in a sample of aspirin would cause the melting point to...
decrease and have a broad melting point range.
53
what class of drugs does asprin belong to
analgesics
54
what are analgesics
medicines that provide relief from pain (analgesia). Some different analgesics include aspirin, acetaminophen/paracetamol and opiates. Some analgesics work at the site of the trauma while others work in the brain to alter the perception of pain.
55
how is asprin primarily used
a pain reliever, fever reducer and anticoagulant
56
side effects of asprin
can irritate the stomach and lead to ulcers if overused
blood thinner
found to improve circulation for diabetics
57
when are prostaglandins produced
When we experience physical trauma, the cells in our body respond with a series of steps that ends with the production of chemical substances called prostaglandins
58
what are antipyretics
fever reducers
59
how does asprin stop prostaglandin production
Aspirin works by stopping the enzyme that produces prostaglandins, which is called cyclooxygenase (known as COX). Aspirin does not have a specific target site, but rather acts to inhibit the production of prostaglandins throughout the body, so any and all pain, swelling or fever will be treated.
60
what is blood made up of
mainly plasma (which has water as a solvent), but also red and white blood cells, antibodies and other substances. Blood is slightly viscous due to the presence of dissolved fats, proteins and other components. Since blood is travelling within a contained system of vessels pumped by the heart, any blockage or leak could have devastating effects.
61
what happens when a blood vessel is damaged
When a blood vessel is damaged, such as when cutting your finger, small fragments of broken blood cells, called platelets, coagulate, or clump together, to stop the leak of blood out of the circulatory system. This is commonly known as blood clotting. Over time, the walls of the vessel can repair itself and the body returns to normal blood flow and pressure. For people with low levels of platelets, such as those with the condition of haemophilia, the blood does not clot well and this can lead to a severe loss of blood or even death.
62
what is a myocardial infarction / heart attack
when a blockage means parts of the body don't receive blood or nutreitns
63
effect of asprin on coagulation
Aspirin works by slowing down the clumping of platelets, so instead of coagulating, they anti-coagulate. People experiencing symptoms of a heart attack or stroke are sometimes recommended to chew two aspirin tablets while on their way to hospital to reduce the severity of the attack. Aspirin can also be taken as a prophylactic, or preventative measure, to slow or prevent the formation of a blockage in the first place. Generally a low dose of aspirin is used for this purpose, and is often recommended to middle-aged or elderly people with a family history of stroke or heart disease, or even for pregnant women, as pregnancy can increase the risk of blood clots.
64
how can the solubility of apsrin be chemically modified to increase its solubility in aqueous solutions
Aspirin can be chemically modified to a salt to increase its solubility in aqueous solutions. By dissolving the acetylsalicylic acid in sodium hydroxide, the hydrogen on the carboxyl functional group is replaced by a sodium ion, as shown in the reaction below, to make sodium acetylsalicylate, sometimes called soluble aspirin.
The sodium acetylsalicylate product is more soluble in water than the aspirin molecule, as ions have a stronger attractive force to the dipoles in water molecules than the intermolecular forces of the carboxyl functional group. Having a product with greater aqueous solubility means that orally ingested sodium acetylsalicylate will reach the stomach more quickly. The bioavailability of soluble aspirin, however, is almost the same as the insoluble form because the ionic salt reacts with stomach acid to produce (insoluble) aspirin. One method of increasing the bioavailability of aspirin is to administer the drug intravenously. As discussed in section D.1.2, this method of administration produces the highest possible bioavailability.
65
asprin and alochol ahev what sort of effect when taken together
a synergistic effect
each drug has a higher medicinal effect when taken in combination than when taken separately
66
Aspirin works as an anticoagulant by
slowing down the clumping of platelets.
67
Modifying aspirin into a salt:
increases aqueous solubility and has a limited effect on its bioavailability
68
how do communicable diseases generally spread
bacteria and viruses
69
The only course of treatment for a virus is
prevention with an immunisation.
70
how is penicllin made now
Populations of fungi are fermented in large, stainless steel tanks under controlled conditions in a sterile environment. In order to produce a stressful environment, scientists provide penicillin with lactose sugar, rather than glucose sugar that the fungus prefers as a food source. The temperature, pH and other nutrients added to the batch also ensure that the fungi are under stress.
71
what is added to tanks of fungi to make penicclin in a stressful environment
lactose not glucose
temp and pH slightly inconvenient
72
The key feature of any penicillin molecule is the
beta-lactam ring. The beta-lactam ring is important for the action of penicillin in preventing the growth of bacteria.
73
what parts of penicllin gives rise to different structures an functions
different side chains for the r group
74
penicllin g
also known as benzyl penicillin, is a very potent antibiotic that has been used successfully to treat syphilis, meningitis and other bacterial infections. Notice that the benzene ring is nonpolar and as a result, penicillin G must be injected to have an effect, as it is not water-soluble enough to be absorbed by oral ingestion.
75
penicllin v
Penicillin V, by contrast, contains an oxygen before the benzene ring. This provides slightly more solubility in water and therefore penicillin V is prescribed as an oral antibiotic to treat minor infections like tonsillitis.
76
Different side chains result in different penicillin molecules.
77
why must penicllin g be injected
Penicillin G is not stable in the acidic environment of the stomach, so it cannot be taken orally and must be injected to have better bioavailability.
78
how is ampicllin produced
by chemically modifying the R group to include an amino group. The presence of this amino group allows ampicillin to better penetrate the cell walls of bacteria and thus has greater action on stopping the growth of bacteria for respiratory infections. The amino group also allows for greater solubility in water, so ampicillin is often prescribed orally, rather than intravenously.
79
cell walls are made with layers of
peptiodglycan
80
what is peptiodglycan
sugars and amino acids known as murein
81
how are layers of peptidoglycan arranged for cell walls
When the layers of peptidoglycan are made for the cell wall, they are cross-linked, which means there are covalent bonds holding the layers together (this is common in polymers). This cross-linking provides additional structure and rigidity for the cell wall.
82
how does cross linking occur
by the action of certain enzymes, known as transpeptidase, also known as the penicillin binding protein (PBP).
83
what happnes if a cell wall is not cross linked
A cell wall that is missing the necessary cross-linking will eventually have too much water entering the cell via osmosis, causing the cell to burst. Since animal cells do not have a cell wall or transpeptidase, penicillins cannot bind, so they have no effect on animal cells.
84
how does bacteria interfere with cross linking
The beta-lactam ring effectively binds to transpeptidase (the penicillin binding protein) and thus interferes with the action of the enzyme, therefore not allowing the cell wall to be cross-linked.
85
Some bacterial infections do not respond to a course of antibiotics. This is because some bacteria are capable of producing enzymes that destroy penicillin. These enzymes are known as
penicillinase or beta-lactamase. Penicillinase works to break the beta-lactam ring in the penicillin molecule, thus rendering it ineffective in binding to transpeptidase (also known as the penicillin binding protein).
86
For example, having a larger, bulkier R-group seems to make penicillin more resistant to ??? so naturally-occurring penicillins can be chemically modified to make penicillin more effective at stopping the growth of bacteria.
penicillinase
87
causes of antibiotic resistance
oversubscription of antibiotics
not following entire prescribed dose
bacteria that produce penicllinase in large quantities are penicillin resistant
88
Beta-lactam antibiotics, such as penicillin, kill bacteria by
preventing cross-linking of peptidoglycan layers in the cell wall.
Penicillin binds to transpeptidase, also known as the penicillin binding protein, to prevent cross-linking of peptidoglycan layers in the cell membrane.
89
Antibiotic resistance is caused by the action of penicillinase, also known as beta-lactamase, which
breaks the beta-lactam ring.
90
what is the active medicinal ingredient in the latex extracted from the opium seed pod
morphine
91
The morphine extracted can be used directly or be processed to make two other drugs, ???? , the latter commonly known as heroin.
codeine and diamorphine
92
codeine, diamorphine and morphine are
analgesics
93
why must opiates be slightly polar
bloood is polar and opiates must travel to the brain
94
why must opiates be slightly non polar
to cross the blood brain barrier
95
functional groups of morphne
two hydroxyl which add polarity and water solubility to the structure
96
how is morhine prescribed
Morphine is prescribed orally in a tablet or liquid or by intramuscular or intravenous injection. The bioavailability of morphine taken orally is approximately 30%.
97
codeine functional groups
one hydroxyl group with an bonded to a methyl alkyl functional group which forms an ether and therefore slightly decreasign the polarity and water solubility. As a result codeine can pass into the brain more easily.
98
which is stronger codeine or morphine
However, codeine is less effective at binding to receptors in the brain and therefore has 1/10 the strength of morphine, so it is only suitable for mild to moderate pain.
99
diamorphine functional groups
two hydroxyl functional groups substituted with O bonded to an acetyl side chains, which forms 2 ester groups and greatly reduces the polarity and solubility in water compared to morphine and codeine. The bioavailability of diamorphine is less than 35% when taken orally.
100
how is diamorphine administered
As a result, diamorphine is generally not taken orally, but is injected intravenously. With the decrease in polarity, diamorphine can pass into the brain much more easily than both morphine or codeine. It also binds to the receptors in the brain more effectively than both morphine and codeine, making diamorphine have 4-5 times the strength of morphine. It is rarely used medically and only for severe pain due to its highly addictive nature. Diamorphine is used recreationally, but is regarded as an illegal drug in many countries.
101
list the opiates in decreasing polarity
morphine
codeine
diamorphine
102
Synthesis of codeine from morphine by a methylation reaction.
Codeine is sometimes referred to as methylmorphine since one hydroxyl functional group is replaced with a methyl alkyl group via a methylation reaction. In this reaction, the morphine is reacted with CH3I (iodomethane, also known as methyl iodide) in an alkaline solution. This makes an ether linkage. This reaction is actually reversed in the liver when the body is breaking down the codeine for elimination.
103
what is different about diamorphine to morphine and codeine
Unlike morphine and codeine, diamorphine is not naturally found in the opium latex and it is only made synthetically by reacting morphine with ethanoic acid in an esterification reaction.
104
describe the synthesis of diamorphine from morphine by an esterification reaction.
The hydroxyl functional groups on the morphine molecule each react by a condensation reaction with the carboxylic functional group on the ethanoic acid. The result is an ester linkage and the elimination of water.
105
Which of the three opiates (morphine, codeine or diamorphine) is the most polar?
morphine
106
When the body experiences a trauma, a chemical pathway occurs with the end result being the production of
prostaglandins
107
what can prostaglandins do
increase body temp
cause a fever
produce the sensation of pain
108
The sensation of pain is caused by
the direct action of prostaglandins on the nerve endings locally at the site of the trauma or by acting on the perception of pain in the central nervous system in the brain.
109
what is the difference between asprin and opiates with how they deal with prostaglandins
Some analgesics, such as aspirin, work to interfere with prostaglandin production and treat pain (and the associated trauma) locally. Other analgesics, like opiates, work to interfere with the sensation of pain in the brain (and do not address the trauma).
110
how does the sensation of pain come about
When the central nervous system receives a pain stimulus from the nerve endings at the site of a trauma, the pain signal is transmitted through the nerve cells, called neurons, to the spinal cord and then the brain. Neurons can communicate to one another using chemicals called neurotransmitters, to transmit the signal faster and across small gaps between neurons, called synapses, where they interact with receptors on the neuron on the other side of the synapse. Specific parts of the brain are then stimulated to give the sensation of pain.
111
what are the natural pain relievers produced by the body
endorphins
112
The structures of an endorphin, the body's natural pain reliever, and morphine, the pain reliever produced by poppies. Note the similarity in structure.
113
how does the body interpret opiates as endorphins
Endorphins bind to endorphin receptors (also called opioid or opiate receptors) in brain cells to intercept the pain signal. Opiates also bind to the same endorphin receptors, since they share a similar chemical structure. As the endorphin receptors cannot tell the difference between a natural endorphin and an opiate, the pain signal is interrupted centrally for the body.
114
describe how dopamine makes opiates addictive
For example, dopamine is a neurotransmitter that is produced when the endorphin receptor binds to a natural endorphin or to an opiate. The release of dopamine causes feelings of pleasure, which adds to the addictive nature of opiates.
115
why is codeine known as a pro drug
About 10% of codeine is metabolised in the liver into morphine, although this can vary between individuals. For this reason, codeine is known as a prodrug; a drug that is converted to a more active form once inside the human body. However, this conversion is quite slow and other products are also made, which have no medicinal effect.
116
why is diamorphien mroe instant acting
Diamorphine contains more nonpolar functional groups than morphine or codeine, so it is faster at crossing into the lipid layer that surrounds the brain. Diamorphine can only bind to one receptor, so the effect of diamorphine is immediate, but does not last long.
117
Which of the following explains why codeine, compared to morphine, is less effective at treating pain?
Codeine is first metabolised in the liver back into morphine
118
most common method of administeration of morphine, codeine and diamorphine
oral oral oral
injection better for morphine and diamorphine
119
order of strength of opiates
codeine
morphine
diamorphine
120
disadv of morphine
Moderately addictive.
Withdrawal if taken for extended periods.
121
adv of morphine
Quickly relieves pain.
Mild side effects.
Option for convenient administration (oral ingestion).
122
adv of codeine
Suitable for mild pain.
Drug is slowly metabolised, so fewer doses are required.
Convenient administration.
123
disadv of codein
addiction
124
disadv of diamorphine
Highly addictive.
Must be injected.
Withdrawal if taken for extended periods.
Drug metabolises quickly, so frequent doses are required.
125
side effects of morphine
Unlike aspirin, which acts at the local site of trauma, morphine affects the body's central pain response in the brain, so there are more side effects. Common side effects that are mild include feeling dizzy, drowsiness, constipation and weight loss. More serious side effects include blurred vision, chest pains and difficulty breathing. Symptoms of an overdose can include constricted pupils, fever, muscle pain or spasms and severe sleepiness.
126
tolerance
decreased medicinal effect of a drug that occurs with extended use of the same dosage. Certain medicines cause a physiological response in the body, making the same dosage of the medicine not as effective. In order to achieve the same medicinal effect, the dosage must be increased with time.
127
what is methadone
Opiates can produce a euphoric sensation at high doses, which results in illegal use and addiction.Methadone is an opiate derivative that can bind to the opiate receptors but does not produce the euphoric effects of morphine. Methadone is an effective treatment option to help with tolerance, addiction and withdrawal symptoms.
128
Structures of morphine, diamorphine (heroin) and methadone.
129
what must antacids contain
a weakish (otherwise could damage mouth and oesphagus) base in order to neutralise the excess hydrochloric acid produced by the stomach
130
calcium carbonate reacts with hydrochloric acicd in a typical neutralisation reaction
CaCO3 (s) + 2HCl (aq) → CaCl2 (aq) + CO2 (g) + H2O (l)
131
neutralisation reaction for hydrochloric acid and aluminium hydroxide
Al(OH)3 (s) + 3HCl (aq) → AlCl3 (aq) + 3H2O (l)
132
neutralisation reaction for hydrochloric acid and neutralisation reaction for hydrochloric acid and magnesium hydroxide
Mg(OH)2 (s) + 2HCl (aq) → MgCl2 (aq) + 2H2O (l)
133
neutralisation reaction for hydrochloric acid and calcium hydroxide
Ca(OH)2 (s) + 2HCl (aq) → CaCl2 (aq) + 2H2O (l)
134
neutralisation reaction for hydrochloric acid and sodium carbonate
Na2CO3 (s) + 2HCl (aq) → 2NaCl (aq) + CO2 (g) + H2O (l)
135
neutralisation reaction for hydrochloric acid and sodium bicarbonate
NaHCO3 (s) + HCl (aq) → NaCl (aq) + CO2 (g) + H2O (l)
136
what are buffers
solutions that resist changes in pH when small amounts of strong acid or strong base are added. If acidic or basic foods are consumed or small amounts of stomach acid are produced or used up during digestion, the pH of the stomach contents can be 'buffered' and maintained within an optimal range of pH 1 to 3.
137
henderson hasselbalch equation
pH=pKa+log([A−] / [HA])
138
H2CO3 (aq) + H2O (l) ⇌ HCO3- (aq) + H3O+ (aq)
If the pH decreases due to the release of too much acid or if acidic foods are consumed, the equilibrium will shift to the left, using up the excess acid. If the pH increases due to acid being used up during digestion or if basic foods are consumed, then the equilibrium will shift to the right to replenish the acid.
139
what is pKa an expression of
the strength of the weak acid
140
the larger value of pKa
the weaker the acid
141
when are antacids effective
for occasional or mild stomach acid issues
142
Which two species are involved in buffering the gastric juices in the stomach?
H2CO3 and HCO3-
143
If the concentrations of the weak acid and conjugate base are the same, then using the Henderson-Hasselbalch equation results in the log term being equal to 0 (the log of 1 is 0). Therefore, the pH is equal to the
pKa of the weak acid
144
There are two main factors to stomach acid production –
synthesis of the acid and the release of the acid into the stomach.
145
which cells produce acid
parietal cells
146
the stimulus to release acid is
triggered by food, stress or an increase in the pH of the stomach contents
147
There are three receptors in the parietal cells that must all be activated to produce and release stomach acid. They are called the
the histamine receptor, gastrin receptor and acetylcholine receptors. Interfering with the action of any of these receptors will stop acid production and release.
148
what is an agonist
a substance that binds to a receptor and fully activates it
149
what is an antangonist
binds to a receptor and blocks it or prevents the action of other agonists
150
are opiates agonists or antagonists
agonist
151
is asprin an agonsit or antagonist
antagonist
152
how do H2 receptor antagonists reduce acid release
One method to decrease acid release into the stomach is with an H2 receptor antagonist drug. One example of an H2 receptor antagonist is ranitidine. This drug interferes with the histamine receptor and blocks its action (the 'H' in H2 antagonist stands for histamine). The result is that acid will not be produced by the cells where ranitidine interferes with the histamine receptor, since all three receptors are required to be activated in order to produce acid
153
active metabolite
the form of the drug after it has been processed by the body
154
ranitidine
The chemical structure of ranitidine has ionic charges, allowing it to dissolve very well in water, making it able to be well absorbed by oral ingestion (40-80% bioavailability), so it is generally swallowed as a tablet or as granules dissolved in water. Ranitidine has a low incidence of side effects: generally headaches are reported, and very few serious side effects have been noted. The drug is effective for about 4-6 hours after ingestion, so it is generally taken twice a day. There are different doses available, depending on the severity of the symptoms.
155
how do proton pump inhibitors work
Proton pump inhibitors (PPIs), such as omeprazole or esomeprazole, work by irreversibly binding to the proton pump with a covalent bond, preventing it from pumping hydrogen ions into the stomach. As a result, PPIs are much more effective than H2 receptor antagonists at relieving the symptoms of excess stomach acid.
156
why does ppi work beter than h2 receptor antagoist
The structure of omeprazole has many polar functional groups, ensuring high bioavailability when taken orally. Omeprazole, like ranitidine, must be metabolised by the liver before the active metabolite can have an effect on acid secretion. Omeprazole can sometimes take up to 24 hours to have an effect, due to the slow metabolism. The active metabolite, however, binds covalently to the proton pump, resulting in a longer-lasting effect compared to ranitidine; sometimes 1-3 days for a single dose. This makes PPIs provide much longer and more permanent relief compared to antacids or H2 receptor antagonists.
157
is omeprazole better for chronic stomach acid problems or occasional issues
chronic
158
side effects of omeprazole
fever, stomach pain, nausea and headaches.
159
Rank the relative effectiveness of different options for treating excess stomach acid from least to most effective and long lasting.
antacids, H2 receptor antagonists, proton pump inhibitors
160
What is the term for the form of a drug that has been processed by the body and now has a medicinal effect?
metabolite
161
viruses recognise specific cell types by
antigens
162
the immune resposne
When a virus attacks a healthy host cell, proteins called antigens on the outside of the cell change. Other cells, called T-cells, recognise that the infected cell is abnormal by the presence of these antigens and the T-cells attack the abnormal cell. In order to stop the viral infection, the T-cells must kill the abnormal host cells before the viruses are formed and released. The body quickly makes more T-cells to stop the continued growth of the virus, which can take a few days. In time, all of the T-cells will have killed all of the host cells and the virus does not have a chance to reproduce.
163
memory cells
The body has a 'memory' for some previous infections and will quickly act to destroy the virus if infected again. While the T-cells are actively seeking and killing infected host cells, other cells called B cells work to recognise the antigens present on the surface of the host cells. The B cells quickly make antibodies that bind to the antigens. When the virus is present, the antibodies surround the virus and macrophages, a type of white blood cell, swallow and destroy the cluster of antibodies and virus.
Some antibodies are made continually, so a second exposure to a virus does not result in a successful infection because the antibodies quickly surround the virus and it is destroyed. Reinfection with the same exact virus does not occur because the body now has lifelong immunity to that virus. Varicella, commonly known as the chicken pox virus, is an example of a viral infection that generally only happens once per lifetime. Other viruses, like the common cold or influenza, have different strains of the same virus, so you can be reinfected with a variation of the same virus over and over again.
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vaccines
When a vaccine is administered containing a heat-killed or live attenuated virus (a virus which has had some of its genetic material removed), the same immune response occurs, but the inactivated virus is not able to cause an infection. The B cells work to produce antibodies in response to the antigens, so immunity is present if the virus were to enter the body.
Some vaccines are only required once to create enough lifelong immunity, while others must have a 'booster' dose to ensure that the body continues to make antibodies. The tetanus vaccine must be given approximately every 10 years, while the smallpox vaccine only requires a single dose for lifelong immunity.
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what are the 3 ways antivirals can work
blocking the virus from entering the cell
interfering with the replication of the virus
interfering with the release of the newly formed virus
166
blocking the virus from entering the cell antiviral
Viruses identify appropriate host cells by binding and docking to specific receptors on the cell membrane. Drugs can be used that either mimic the virus to bind to the cell receptors or that mimic the cell receptors to bind to the virus. Designing effective molecules to interfere with the virus-receptor binding action is a challenge.
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blockign the entry of genetic material from the virus into the host cell antiviral
Another method is to block the entry of the genetic material from the virus into the host cell. Once the virus docks to the receptor, it must inject its genetic material into the host cell, which requires some help from the host cell to allow foreign material to enter. Cell membranes are selectively permeable to allow needed nutrients into the cell and to maintain a barrier for the protection of the cell against damaging material. Drugs that interfere with the ability of the viral genetic material to enter the host cell are effective at preventing the virus from reproducing.
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interfering with the replciation of the virus antiviral
The virus uses the host cell's machinery to reproduce, so some antiviral medicines can interfere with this process, producing incomplete viruses. Some drugs introduce inactive genetic building blocks into infected host cells. When used to make new viruses, inactivated genetic building blocks then produce viruses which are ineffective. Other medicines interfere with the host's ability to generate the protein capsule for the virus, so that the newly made viruses do not have the structure and protection of that outer capsule.
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Interfering with the release of the newly-formed viruses antiviral
Once the assembled viruses are ready to be released, the host cell must activate certain proteins to allow the viruses out. Drugs can be used to block the action of these 'release molecules'. The newly made viruses are then trapped inside the host cell and are not able to be released to infect other healthy cells.
170
How do vaccines and antiviral medicines differ?
Vaccines are given before infection to provide immunity. Antiviral medicines are given after infection to reduce the symptoms and severity of the illness.
171
what are the two antivirals used to treat influenza
oseltamivir
zanamivir
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structures of oseltamivir and zanamivir
Note that there are some similarities in the structures of the two antivirals. Attached to the ring structures of both molecules are the following functional groups: a carboxamide group, an amino group and an ether group. Both rings also contain a carbon-carbon double bond. Zanamivir has a carboxyl group and multiple hydroxyl groups which make it more soluble in polar solvents than oseltamivir.
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In order for the virus to leave the host cell, an enzyme on the virus, called ???, cuts through the host's cell membrane
neuraminidase
174
who is zanamivir not recommended for
indiviuals with respiratory problems
175
method of adminsterationf or oseltamivir vs zanamivir
oral tablet vs oral inhalation
176
which strains are oseltamivir and zamamivir more effective for
a and then b
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antigenic drift
small mistkaes are made in the reproduction process, resulting in changes to the proteins on the outside of the virus, making a new strain. When this occurs, the immune system does not recognise the virus any more and it can infect host cells, even if immunity to a different strain of the virus had already been established.
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antigenic shift
where two or more different strains of the virus infect the same cell, producing a new hybrid strain. The hybrid strain now contains a combination of different proteins on the outside of the virus, which the immune system is not able to recognise and fight.
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Oseltamivir and zanamivir combat the influenza virus by
Blocking the release of newly formed viruses from the host cell.
180
Identify three functional groups that are present on both influenza antiviral medicines.
ether, carboxamide (amide), amino
181
what does HIV do
The human immunodeficiency virus, or HIV, attacks the cells that make up the body's immune system. If left untreated, HIV develops into acquired immune deficiency syndrome, or AIDS. In the past, an HIV diagnosis was certainly a death sentence, but today HIV-positive individuals can live long and relatively healthy lives with the right combination of medicines, the most powerful drugs being antivirals.
182
symptoms of HIV infection
183
what is the only way HIV can be transmited
by certain bodily fluids such as blood, breast milk, vaginal fluids or semen, where the virus is in higher concentration. It cannot be transmitted by casual contact, such as shaking hands or sharing a glass of water, or through saliva or nasal secretions. The viral load in these secretions is too low and the virus does not survive well outside of an infected person.
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what type of cell does the HIV virus attack
The HIV virus attacks a type of T-cells that contain a CD4 antigen (sometimes called CD4 cells) to reproduce and make more viruses. CD4 cells, like all T-cells, are part of the body's immune response, so the problem with an HIV infection is that over time, the CD4 cells that are involved in producing more viruses are killed when the CD4 cell bursts open, releasing the newly-made viruses. Depleting the body's immune system response weakens it, leaving the body susceptible to any form of infection. In time, when nearly all the CD4 cells are gone, the patient would be diagnosed with AIDS and even a common cold virus could result in death.
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what is a retrovirus
, a special type of virus that contains slightly different genetic material than a traditional virus (it contains a single strand of RNA compared to a double strand of DNA in a traditional virus).
186
Antivirals used to treat retroviruses are called
antiretroviral medicines
187
Taking ART can be very effective at reducing the patient's
viral load, the concentration of virus in a blood sample, to undetectable levels in the blood, ensuring a longer, healthier life and reducing the risk of transmission to other people.
188
what is ART
antiretroviral treatment, a mixture of different antiretroviral drugs to target the different stages of the retrovirus life
189
are there vaccines for retroviruses
no
Since a retrovirus contains RNA, which is then converted to DNA and incorporated into the host cell's own genetic material, the HIV viral DNA can remain dormant (inactive) in the host cell for years before it begins to produce viruses and the person shows symptoms of the illness. Since the virus can remain inactive, the presentation of illness may be delayed and therefore the efficacy of the vaccine may be difficult to measure.
190
One reason why the HIV virus is more difficult to combat than most other viruses is because
It is a retrovirus that contains RNA, rather than DNA.
191
how much of the inital mass does the solvent account for
80-80%
192
polar solvents
water
alcohols
193
non polar solvents
alkanes, like hexane or heptane
benzene and benzene derivatives
ethers, like tetrahydrofuran
194
which is easier to dispose of polar or non polar solvents
poalar. some non polar solvents like benzene are cancerous
195
antibiotic resistance can occur by
not following full course
improper disposal
given to animals
196
what can be nuclear waste
Nuclear waste can be produced from unused samples of radioisotopes used and also from any materials or equipment that have come in contact with the radioisotopes. All objects that have come in contact, or have come in close proximity, with these isotopes must be collected and disposed of carefully. These objects could include syringes, disposable gloves, bedding and other absorbent materials, cotton swabs and vials.
197
what can nuclear waste emit
gamma radiation
198
Exposure to significant gamma radiation results in
radiation sickness, which can occur from drinking contaminated water, eating fruits or vegetables grown in contaminated water or even just by being in close proximity to a source of radioactive isotopes. Low-dose exposure to gamma radiation can result in skin rashes, nausea, diarrhoea and vomiting. High-dose exposure can result in cancer, decreased fertility or death. The treatment for radiation sickness is with antibiotics, blood transfusions and even stem cell transplants.
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what is nuclear waste categorised into
high level waste and low level waste
200
hlw
contains a greater radioactive content and is typically produced from spent uranium fuel from nuclear reactors and other liquid waste that comes in contact with the fuel.
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llw
contains less radioactive content and typically includes protective clothing, tools and cleaning materials used at nuclear power generating stations and also the nuclear medical waste generated from hospitals, which includes patient linens, used syringes and empty vials.
202
storage of hlw
generates a lot of heat during the radioactive decay process and is typically stored in large pools of water, called wet storage, until the level of radiation is low enough that it can be safely transported and stored in steel cylinders, dry storage.
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storage of llw
safe enough that it can be transported to a central storage facility and stored in dry storage. The steel cylinders in dry storage can be buried and encased in concrete or additional steel to limit the amount of radiation emitted. The steel cylinders must be resistant to corrosion, to avoid leaks, and are also welded shut.
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what happens if nuclear waste is not stored properly
the risk of exposure to people, animals, plants and the environment can be high. The rate of radioactive decay for isotopes can be minutes, hours, days or years, so appropriate measures to keep the waste away from people, including the workers that are employed to handle the waste, must be done carefully. The transportation of nuclear waste by transport truck or railway from one location to another is also risky in the event that there is a spill, traffic accident or derailment.
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what does green chemistry aim to do
reduce waste and energy to produce safer compounds and to limit the use and production of dangerous or harmful compounds in the process.
206
green chem principle of atom economy
In the synthesis of a compound, all materials used in the production should be incorporated into the final product, rather than having leftover materials or byproducts.
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green chem principle of less hazardous chemical design and synthesis
Compounds with little or no toxicity should be developed and synthesised, rather than ones with toxic effects.
208
Some of the solvent waste can be recycled and used again, using
fraction distillation equipment.
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how does fraction distillationw ork
by heating up the leftover solvent mixtures and separating the components (fractions) by boiling points. The pure fractions of the mixture are then collected, and solvents can be recycled and any other fractions can be discarded. Recovering solvents does have an initial cost to the company in the purchase of the equipment, but they save money later on since the companies do not have to purchase as much solvent in the future.
210
what is biodegradation
Some solvents, such as benzene and its derivatives, can be incinerated in a combustion reaction or, when diluted with water, can be decomposed by bacteria.
This process produces the same products as with incineration, but with a lower energy cost since heat is not required to burn the solvent. Biodegradation is also considered to be a more green process, since carbon dioxide gas is being released at a much slower rate than incineration.
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One example of a successful green chemistry practise is in the synthesis of the antiviral drug oseltamivir, known by the trade name Tamiflu.
. The precursor for the synthesis of the drug is found naturally in certain plants, such as the sweetgum plant, certain pine needles and also from the Illicium verum plant, commonly known as Chinese star anise. The precursor, shikimic acid, is present in concentrations of 3-7% in the star anise seeds. When the demand for oseltamivir increased beyond the ability to produce it, scientists had to find another way of obtaining shikimic acid that did not put the population of the star anise plant at risk. Shikimic acid has now been successfully produced using bacteria in the process of biosynthesis. Escherichia coli can produce large quantities of shikimic acid in a multi-step process, which has decreased the demand for the star anise plant. E. coli need a source of carbohydrates (sugar) and a controlled temperature condition that is close to room temperature, so the reaction conditions are cost- and energy-effective. This is an example of a green chemistry solution to synthetically produce larger quantities of a naturally-occurring compound using bacteria to minimise the energy consumption and waste production while minimising the use of solvents.
212
Enantiomers are referred to as optical isomers because
they exhibit optical activity.
213
how can two enantiomers be distinguished
using plane polarised light from a polarimeter. Each enantiomer will rotate plane polarised light by an equal magnitude, but in opposite directions. A polarimeter is used to identify which enantiomer is present in a sample.
214
what is a polarimeter used for
to indentify which enantiomer is in edch smaple
215
what is a racemic mixture
A mixture containing an equal proportion of both enantiomers
216
whats wasteful about racemic mixtures
During a typical reaction that forms enantiomers, both enantiomers can be formed, sometimes in equal amounts, forming a racemic mixture. The two enantiomers would then have to be separated and the incorrect one discarded, leading to greater waste production, higher costs and lower yields.
217
what are chiral auxiliaries
compounds that contain a chiral centre, which are inserted during the drug synthesis phase to promote the production of the correct enantiomer. The chiral auxiliary can then be removed at a later step in the drug synthesis after the specific chiral centre in the drug is made.
218
what is cancer
the uncontrolled growth and division of cells that make a mass, known as a tumour, that spreads to other parts of the body, causing more tumours to form
219
why is cell divison required
Cell division is required for the growth of the organism, to repair damaged cells and to replace old cells that can no longer perform cellular functions efficiently. When errors in cell division occur or if a cell becomes damaged, there are checkpoints present in the cell life cycle to repair the cell or for the cell to undergo apoptosis, cell suicide or programmed cell death, if the damage cannot be repaired.
220
what is apoptosis
cell suicide or programmed cell death
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how can a tumour begin
When a cell is exposed to chemicals or gamma radiation that cause damage to the DNA, the cell becomes mutated and can grow out of control. These damaged cells no longer have the necessary checkpoints to be sure that the cell is dividing at the right time or for the right reasons. The cells are damaged beyond the ability for repair and the checkpoint for apoptosis is gone or malfunctions, resulting in the formation of a cancer cell. For cancer cells, the rapid cell division often results in the production of even more imperfect cells that grow together as a mass, known as a tumour.
222
how is taxol adminsitered
intravenously
223
side effects of taxol
nausea, vomiting, loss of hair and tingling in the hands and feet. female infertility, exhaustion
224
what tree is the soruce of taxol
pacific yew tree
225
how is taxol now synthesised
semi-synthesised chemically using a precursor from the needles of the European yew tree, which regenerate quickly and do not require the destruction of the entire tree.
226
how does taxol work
When Taxol is present, cell division stops at the phase known as metaphase and the cell 'arrests' or freezes. Taxol specifically interferes with the development of spindle fibres. Spindle fibres extend through the cell during cell division and help to divide the genetic material evenly between the two newly formed cells. When Taxol is present, more spindle fibres are produced and at a faster rate than normal, clogging up the cell and not allowing the genetic material to divide into two cells.These cancer cells now cannot finish cell division and are more likely to have the apoptosis checkpoint initiated, leading to cell death. When the cancer cells respond to Taxol, doctors observe the tumour to decrease in size due to cell death, and further treatment of Taxol is associated with a reduction in the reoccurrence of the cancer returning.
227
what is a antimitotic drug
interfering with cell division or mitosis
228
when is taxol given
weekly or less frequently, slwoly over the course of 3-24 hours
229
Taxol is now produced synthetically or semisynthetically, but originally was obtained from which source?
The bark of the Pacific yew tree
230
What type of compound is required in the semi-synthesis of Taxol to ensure the formation of the correct enantiomer? Answer contains two words.
chiral auxiliary
231
alpha emission
4α2 or 4He2
charge of 2+
relative mass of 4
232
beta emission
0 β- -1 or 0 e- -1
charge of 1-
relative mass of 0
233
proton emission
1 p + 1 or 1 H+ 1
charge of 1+
0 relative mass
234
positron emission
0β+ +1 or e+ or 0 e+ +1
1+ charge
0 relative mass
235
gamma emission
γ or 0γ0
0 charge
0 rel mass
236
how are gamma rays different to x rays
greater energy, shorter wavelengths and higher frequency. As a result, gamma rays that are emitted during nuclear decay can penetrate through cement, while x-rays cannot.
237
which forms of radiation have the worst and best penetrating power
238
half life is
the period of time required for half of the number of atoms to decay to more stable nuclei
239
For radioisotopes with a very short half-life, the patient can be discharged after
the procedure
240
For isotopes that have a longer half-life, the patient must be
admitted to the hospital and monitored until enough gamma radiation has decreased before the patient can be released.
241
why is Technetium-99m widely used in medicine
short half life of 6 hours
242
how is Tc-99m stored
To overcome storage challenges arising from its rapid decomposition, Tc-99m is generated on-site in hospitals using a generator from the decay of molybdenum-99.
243
what does the m in Tc-99m mean
The 'm' in Tc-99m indicates its metastable nature, existing in an extended excited state with higher energy electrons than the ground-state configuration. Its decay primarily involves gamma decay, releasing substantial gamma radiation ideal for medical imaging. This is advantageous as gamma rays are efficiently emitted by the body and easily detected, unlike alpha or beta particles, which have limited penetrating power and may remain in the body.
244
rules of balancing nuclear equations
Nuclear equations are balanced differently from chemical reaction equations, since there are often changes to the numbers of subatomic particles. Therefore, balancing nuclear equations requires accounting for the atomic number and atomic mass number on both sides of the reaction arrow. The sum total of the atomic number(s) left of the arrow must equal the sum total of the atomic number(s) on the right. The same rule applies to the atomic mass number. Since gamma rays do not have mass, they can be included in nuclear equations, but they do not affect the balancing.
245
MRI
MRI uses a strong magnetic field to influence the protons and neutrons, known collectively as nucleons, in the nuclei of atoms and radio waves to generate images. Atoms with an odd number of nucleons can be detected using MRI. Since 80% of the body's atoms are hydrogen, and 99.98% of hydrogen atoms contain one proton, hydrogen atoms are present throughout the body, generally in water molecules, and these can easily be detected by MRI.
246
why is mri more safe
it uses a magnetic field not gamma radiation
247
Technetium-99m is the most popular radioisotope used in medical imaging due to its
short half-life and stable decay products
248
MRI (magnetic resonance imaging) is an application of which type of technology? Answer with a three letter acronym.
nmr
249
Brachytherapy
administers a source of gamma radiation that can be implanted through a wire (catheter) to a targeted area, such as an organ, allowing other healthy tissues to avoid exposure.
250
Gamma knife radiosurgery is a form of external radiotherapy that
targets gamma rays from cobalt-60 to a target site in the body.
251
how does radiotherapy work
Radiotherapy works effectively with strong beta particle-emitting radioisotopes. When cells are exposed to beta particles and gamma radiation, the DNA becomes damaged. Gamma radiation treatment generates the formation of free radicals in cells, which cause cellular damage. Damage from free radicals can be repaired in cells, but since cancer cells divide much faster than healthy cells, they are more likely to already have higher levels of free radicals and mistakes in their genetic material that prevent the cell from being able to repair itself. Healthy cells are better able to repair the damage from gamma radiation, but since cancer cells are already damaged, exposure to gamma radiation can cause irreparable damage and eventually lead to cell death.
252
Lutetium-177 is a commonly used radioisotope for cancer treatment because
Its popularity is due to its relatively short half-life and the high rate of beta decay. and stable decay products
253
Yttrium-90 is also commonly used for cancer treatment because
it has an even shorter half life than lutetium-77 and stable decay products
254
minor side effects of chemo
Skin irritation or hair loss at the site of applied radiation.
Fatigue.
Loss of appetite or nausea.
255
serious side effects of chemo
Diarrhoea or other digestive upset.
Urinary or other bladder changes.
Sterility (loss of fertility).
Memory loss.
Formation of new cancer due to exposure to gamma rays damaging healthy cells, making them cancerous.
Scar tissue formation, leading to restricted movement.
Reduced immunity, leading to other infections.
256
The severity of the side-effects depends on the amount of radiation being applied
the age of the patient and the location of the cancer
257
The emission of which type of particles can be used in radiotherapy?
beta particles
258
Lutetium-177 and yttrium-90 are commonly used for radiotherapy due to their
short half-life, high rate of beta emission and stable products after decay
259
what is the diff with conventional radiotherapy and TAT
its a newer form of cancer treatment involving radioisotopes that emit alpha particles
260
why is TAT more effective
alpha particles are much more ionising than beta particles
261
how does TAT only attack specific cells
TAT involves attaching alpha-emitting particles to an antibody via a small molecule called a chelator, a compound that is capable of forming multiple bonds to a transition metal ion to form a complex ion. An antibody is a special protein that is able to bind specifically to cancer cells that contain a particular antigen, a protein on the cell surface. This ensures that only certain cells are being exposed to the radioisotope, thus 'targeting' the therapy to only cancer cells and not healthy ones.
262
TAT picture
263
how is TAT effective at targeting cells that have broken away from the first tumour
it can locate and bind to cancer cells that have spread to other parts of the body by allowing the antibody to recognise and bind to the antigen. TAT is therefore more effective in treating cancers that have spread, decreasing the chance that the cancer can reappear.
264
why is TAT better for blood borne cancers
External or internal radiotherapy would put all healthy cells at risk of exposure to gamma radiation, so TAT provides a better solution because the radioisotope can be injected into the bloodstream, where it can find and locate only those cells with the specific antigen, sparing the healthy cells.
265
what does BNCT use
a non radioactive isotope, boron 10 for cancers in the head and neck.
Boron-10 has been observed to effectively capture slow-moving, low-energy neutrons, forming boron-11, which rapidly decays, resulting in the release of an alpha particle as shown in the reaction below:
105B + 10n → 115B
115B → 42α + 73Li + γ
266
what is the treatment process for BNCT and how does it work
In this treatment, boron-10 is first administered to the patient by injection and is absorbed by the cancer cells. The boron-10 is attached to a small molecule that is readily absorbed by cancer cells, but not by healthy cells. Then, a beam of neutrons is applied externally. The boron-10 atoms then absorb the neutrons and the reaction occurs, releasing gamma radiation, killing the cell from the inside. Since only those cells that have absorbed the boron-10 can absorb the neutrons and undergo the nuclear reaction, this targeted form of therapy spares healthy cells.
267
what is the benefit tot BNCT
BNCT is effective in treating some cancers that do not respond well to other forms of radiotherapy or chemotherapy, especially those in sensitive areas of the brain that are difficult to access. It is also less invasive, as it only requires an injection to deliver the boron-10 and externally applied neutrons. The neutron beam can cause some skin sensitivity in some patients, but overall less gamma radiation is applied to the patient.
268
half lfie is
the length of time for half of the number of atoms to decay forming the non radioactive isotope.
269
Radioisotopes that are used for radiotherapy must have a half-life that is ??? enough to be medically effective, but ??? enough to minimise the amount of excess radiation emitted.
long
short
270
halflife symbol
t 1/2
271
First order reactions have a rate that is
dependent directly on the concentration of the isotope, so as the concentration decreases, the rate also decreases proportionally.
272
how to calcualte the conc of radioisotope left in agiven sample use this equation
273
what does N0 represent
original conc of radiosiotope measured in mol dm -3
274
what does Nt represent
concentration of radioisotope measuredin mol dm -3
275
how is liquid liquid extraction carried out and when
A separatory funnel is a piece of equipment that is often used to extract an organic compound from a mixture. Two solvents, one polar and one nonpolar, will form layers when placed together as they cannot dissolve in each other. The relative densities of the two solvents will determine which layer is on top (lower density) and which is on the bottom (higher density). The mixture is then placed in the funnel with the two solvents and then shaken (and vented to relieve gas pressure), allowing all compounds to mix and interact with the solvents. The funnel and contents are then allowed to settle, where the compounds will separate based on their interaction with either of the two solvents. The funnel stop cock valve can then be opened, separating one solvent from the other, obtaining the desired compound.
276
what is liquid liquid extraciton
where two solvents – one polar and one nonpolar – are used together to partition, or separate, the components of the mixture using solubility. When an organic compound is extracted directly from a natural source or prepared synthetically in a chemical reaction and then extracted from the reaction mixture, the difference in polarity of the two solvents can be used to separate the polar from nonpolar components of the mixture. If the compound to be extracted is polar, then a polar solvent (such as water or a short-chain alcohol) will dissolve the polar solute. If the compound is nonpolar, then a nonpolar solvent (such as benzene or carbon tetrachloride) must be used. For substances that have both polar and nonpolar functional groups, a series of extractions may be required to isolate the desired compound.
277
how is purification done
Extraction methods will isolate and separate based on polarity, but similar compounds can still be extracted and removed together. The active medicinal compound must not contain any impurities that might interfere with its action or cause other toxic effects.
278
fractional distillation
Gently heating a mixture will cause each component of the mixture to boil and evaporate from lowest to highest boiling point, effectively separating each substance individually, as the temperature increases. Distillation equipment is used to collect each substance, referred to as a fraction.
279
raoults law
When a volatile liquid is in a closed container, it is in equilibrium with its own gas. The rate of evaporation is equal to the rate of condensation in a dynamic equilibrium. The gas exerts its own vapour pressure in the closed container.
liquid ⇌ gas
When a mixture contains two miscible, volatile liquids in a closed container, each liquid exerts its own vapour pressure independently of the other. The ratio of the vapour pressures of each gas of the mixture is relative to the vapour pressure of each gas and the mole ratio of each gas, as explained by Raoult's Law.
280
daltons law of partial pressures
The combined vapour pressure of both gases is the sum of each individual vapour pressure
the total pressure exerted by the mixture is equal to the sum of the partial pressures of individual gases.
Ptotal = P1 + P2 + P3
281
what is partial pressure
The partial pressure of a gas in a mixture is the pressure that the gas would exert if it occupied the entire volume alone. It is the pressure exerted by a particular gas in a mixture independently of the other gases.
282
One calculation involving Raoult's Law is to determine the vapour pressure of each solvent in a mixture using the formula:
PA=XA PoA
PA is the observed vapour pressure of the solvent in the mixture, XA is the mole fraction of the solvent in the mixture and P oA is the vapour pressure of the pure solvent.
283
how does infrared spectroscopy work
uses infrared radiation to bend and stretch covalent bonds, changing the dipole moment of polar bonds. The energy absorbed for the bending and stretching is helpful in identifying the type of bonds present in the molecule, thus identifying particular functional groups for organic molecules.
284
what is the fingerprint region
The fingerprint region is the area of the spectrum below 1500 cm-1. Each compound produces a characteristic pattern, or fingerprint, that can be used to identify the molecule against a known database of compounds.
285
how do yo udetermine functional groups using ir spec
One method of analysis of the infrared spectrum is to use a table of infrared data (see Section 26 in the data booklet) to identify specific bonds, as each type of bond will absorb a particular range of energy, measured by wave number, cm-1. Identifying the absorbance and relating it to a bond can determine the functional groups present in the compound, but not their arrangement within the molecule.
286
what can ir spec do and not do
Infrared spectroscopy can identify carbon-hydrogen bonds and the hydroxyl, ester and carboxyl groups, but not the quantity or placement of these groups in the molecule, so further analysis with mass spectroscopy or NMR would be required to further identify the compound.
287
hwo does mass spec work
Mass spectrometry analyses a pure compound by charging and accelerating the molecule, causing it to fragment. These fragments are then detected by the mass-to-charge ratio (m/e or m/z), piecing together the different components of the compound. The peak with the highest m/e ratio corresponds to the relative formula mass of the entire compound and the smaller peaks correspond to fragments of the compound. The fragment pattern of the mass spectrum can be very helpful in identifying both the molecular formula for the entire compound and the formula for some of the fragments. The fragment pattern can also be used to identify the compound from a database of known molecules, just like a fingerprint match.
288
what do the significant peaks in mass spec represent
fragments of the compound
289
The peak with the highest m/e ratio corresponds to
the relative formula mass of the entire compound
290
which spectrospic method is the most diagnostic
1H NMR
291
how does nmr work
NMR uses a strong magnetic field to influence the spin of protons and neutrons inside the nucleus of atoms. For atoms with an odd number of nucleons (protons + neutrons), NMR can influence and detect these atoms, so NMR is commonly used for isotope hydrogen-1, but also sometimes for carbon-13.
292
what does nmr provide info on
1H NMR data provides the information for the number of hydrogen environments from the number of peaks, the number of hydrogen atoms within each environment from the integration trace, the number of neighbouring hydrogen atoms from the split pattern and also the likely type of bond the hydrogen is involved in from the chemical shift. Analysis of NMR, especially when used in combination with IR and mass spectrometry, provides much more detail about the structure of the molecule.
293
how is drunkness measured
blood alcohol conc using a breathalyser
294
how is bac expressed
typically expressed as a percentage of the mass of ethanol per volume or mass of blood, or by mass of ethanol per litre of breath, if a breathalyser apparatus is used.
295
redox breathalyser equations
Oxidation: CH3CH2OH (g) + H2O (l) → CH3COOH (aq) + 4H+ (aq) + 4e-
Reduction: Cr2O72-(aq) + 14H+ (aq) + 6e- → 2Cr3+(aq) + 7H2O (l)
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how does redox breathlyser work
One type of breathalyser apparatus uses a redox reaction to measure the concentration of ethanol, based on the oxidation of the alcohol. Ethanol in the presence of an oxidising agent, such as potassium dichromate, will undergo oxidation to form ethanoic acid. When this reaction occurs, the dichromate ion, which is orange, undergoes reduction to form chromium sulfate, which is green. The vibrancy of colour is then analysed by a spectrophotometer and equated to the concentration of ethanol in the breath and in the blood.
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how does a fuel cell breathlyser work
When breath containing ethanol passes over the platinum electrodes in the breathalyser apparatus, the platinum oxidises the ethanol to form ethanoic acid and the oxygen in the air is reduced. This reaction generates an electric current that is equated to a blood alcohol content in the breath or blood. Fuel cell breathalysers are more accurate than redox breathalysers, but are more expensive.
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diff between redox and fuel cell breathluser
Another type of breathalyser uses a redox reaction and fuel cell technology. Fuel cells are voltaic (galvanic) cells that produce electricity from a redox reaction. The difference between a typical voltaic cell and a fuel cell is that fuel cells require a continuous fuel source, so they can operate as long as the fuel is supplied, whereas typical voltaic cells will eventually run out when the materials undergoing the redox reaction inside the cell (battery) run out. Fuel cells have been used in spacecraft and satellites for quite some time and have been more recently developed for use in vehicles as an alternative fuel source.
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fuel cell breathalyser equations
Oxidation: CH3CH2OH (g) + H2O (l) → CH3COOH (aq) + 4H+ (aq) + 4e-
Reduction: O2 (g) + 4H+ (aq) + 4e- → 2H2O (l)
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negatives of taking testosterone
such as loss of hair and decreased fertility.
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key diffs between oral and injective steroids
Oral steroids are convenient, fast-acting and they clear from the body weeks after use, but their effects are short-lived. Injectable steroids are more difficult to administer and remain in the body longer for a prolonged medicinal effect that is more manageable to control, but also detectable for months after use.
302
how can you test for steroid use
Testing for the presence of steroids in the blood, urine or hair follicle can be done using spectroscopic methods, often a combination of mass spectroscopy and chromatography. The presence or absence of a steroid, as well as the quantity, can be detected even at very low concentrations.
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how id gas liquid chromatograpy used for steroid detection
For steroid testing, gas-liquid chromatography (GLC) is often used. The sample is first heated to be vaporised and passed through a long, coiled column, separating the analytes based on boiling point. The analytes travel through the column and are then detected by a sensor when they exit the column. The length of time it takes for the analyte to leave and the relative intensity of the peak of the analyte are both used to determine the identity and quantity of the substance, respectively.
The analysis produces a peak for each analyte. The area under the curve for each peak can be used to give the relative ratio of the concentration for each analyte in the sample. The retention time – the time required for the sample to reach the detector – can be compared with the known retention times of compounds to identify the compound. GLC analysis is useful for identifying the presence and quantity of various drugs in urine or blood, and also the metabolites from steroids, such as testosterone, in order to compare these results from the athletes to the levels of naturally-occurring testosterone in the system of a nonathlete.
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how ismass spec used for steroid detection
The analysis from a mass spectrometer produces a mass to charge ratio, expressed as m/e or m/z. Since all fragments produced during mass spectroscopy have a positive charge from the loss of one or more electrons, all fragments produced are detected by analysis of their mass. The fragment with the largest mass can be used to determine the relative formula mass of the entire compound, which alone can sometimes be used for identification. The other fragments, and their intensities, can be used to identify some of the likely functional groups or portions of the compound. Steroids, such as testosterone, will fragment into different sizes that can then be pieced together to determine the structure of the entire compound.
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For redox breathalysers, what species undergoes a colour change as a means of monitoring the chemical reaction?
dichromate ion
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Which method – chromatography or mass spectroscopy – is used to identify the presence and relative concentration of unknown compounds in a sample of an athlete's blood, urine or hair follicle?
chromatography
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