Block One Flashcards
(133 cards)
1
Q
What is Pharmacokinetics ?
A
Deals with the absorption, distribution, biotransformation and excretion of drugs and their metabolites in the body
2
Q
What is Pharmacodynamics?
A
Study of the biochemical and physiological effects of the drugs as well as their mechanisms of action
3
Q
What is Pharmacogenetics?
A
Study of the role of genes in determining drug metabolism
4
Q
What is a drug?
A
Any chemical that enters the body and has some physiological effect on the body
5
Q
What is the chemical name of a drug?
A
Derived from the drugs chemical structure
6
Q
What is the generic name of a drug?
A
The official (simplified) chemical name of a drug which describes an active constituent of a medicine
7
Q
What is the brand name of a drug?
A
The commercial name
8
Q
What is the group name of a drug?
A
- Describes the drug class or category to which the drug (or drugs) belongs
- Reflects the pharmacological actions of the drug or the therapeutic area of use of the drug
9
Q
What are the four main categories of adverse drug reactions?
A
- A (augmented)
- B (bizarre)
- C (continuous)
- D (delayed)
10
Q
What is a type A (augmented) adverse reaction?
A
- Predictable, based on pharmacological action of the drug and dose dependent
- Extension of pharmacological effect
11
Q
What is a type B (bizarre) adverse reaction?
A
Unpredictable and not dose dependant
12
Q
What is the mode of action of a drug
A
- This is the mechanism by which the drug exerts its effect on the body
- Drug effect at the cellular or biochemical level
13
Q
What is a therapeutic dose?
A
The smallest amount that will elicit a response and the largest dose that can be tolerated without excessive side effects
14
Q
What is the therapeutic window?
A
The gap between the dose needed to produce the desired effect in 50% of the population and that needed for the undesired effect
15
Q
What is the therapeutic index?
A
Estimation on the margin of safety of a drug
16
Q
What are examples of narrow therapeutic index drugs?
A
- Digoxin
- Warfarin
- Phenytoin
- Gentamicin
17
Q
What is necessary for drugs with narrow therapeutic windows?
A
Therapeutic drug monitoring to prevent toxic effects
18
Q
What are OTC (over the counter) medications?
A
Medications available to the public without a prescription
19
Q
What is complementary and alternative medicine (CAM)?
A
Therapies and treatments that are not commonly accepted in conventional medical practice e.g. herbal, nutritional supplements, traditional medicine
20
Q
What are pharmacy only drugs?
A
Medicines only sold in a community or hospital pharmacy, or a shop in an isolated area that is licensed to sell that particular medicine
21
Q
What is Restricted Medicine (Pharmacist only Medicine)?
A
Medicines which may be sold without a prescription, but the sale must be made by a registered pharmacist, in a pharmacy, and details of the sale must be recorded
22
Q
What are the five rights of drug administration?
A
- Right drug
- Right dose
- Right client
- Right route
- Right time
23
Q
What are the four phases of pharmacokinetics?
A
- Absorption
- Distribution
- Metabolism
- Excretion
24
Q
What is the drug movement during the four phases of pharmacokinetics?
A
- Into blood from site of administration.
- Once in the blood drugs must cross membranes to reach their site of action
- Must cross membranes to undergo metabolism and excretion
25
What drugs cross the membrane easiest?
- Lipid soluble
- Uncharged
- Small particles
26
Which of the four phases are important for elimination of the drug?
Metabolism and excretion
27
How does a drug move from the administration site to blood?
- Most drugs cross membranes by passive diffusion but some drugs need a carrier mediated transport
- Small molecules will diffuse more rapidly than large molecules
- Lipid soluble nonionised drugs are absorbed faster
- Absorption is affected by blood flow, pain, stress etc
28
How is the movement of the drug in the body determined?
Distribution determined by blood flow to tissues; ability of drug to enter vasculature system and ability of drugs to enter cell
29
What is plasma protein binding?
1. Most drugs travel in the plasma partly in solution in the plasma water and partly bound to plasma proteins. The ratio of bound to unbound varies between drugs.
2. Binding is reversible. The bound drug is inactive. Only the unbound drug can cross membranes.
3. Generally acidic drugs bind to albumin.
4. Basic drugs bind to alpha1-acid glycoprotein.
30
What is tissue distribution?
1. After absorption, most drugs are distributed in the blood to the body tissues where they have their effects, both therapeutic and toxic.
2. Degree to which a given drug is likely to accumulate in the tissue is due to its lipophilicity (fat-like) and local blood flow of the tissue.
31
What is metabolism or biotransformation?
The process of transformation of a drug within the body in order to make it more hydrophillic (water soluble) so that it can be excreted by the kidneys
32
What are consequences of drug metabolism?
- Make more soluble compound so it can be excreted
- Conversion of drug to less active or inactive form
- Conversion of drug to more active form than the original drug
- Conversion of drug to more toxic form
- Conversion of prodrug to active form
33
What are the phases in the liver for drug metabolism?
- Phase I reactions (nonsynthetic) – drugs oxidised or reduced to more polar form
- Phase II reactions (synthetic) – conjugation of the drug to a polar group occurs.
34
How do drugs affect liver enzymes?
Some drugs stimulate or inhibit synthesis of liver (hepatic) metabolising enzymes
35
What is first pass effect/metabolism?
When drugs do not enter the systemic circulation first but rather the liver
36
What is bioavailability?
The percent of administered drug dose that reaches the
| systemic circulation
37
What is excretion?
The process by which a drug is excreted from the body
- Renal excretion major route: most important processes are glomerular filtration, tubular secretion, and tubular reabsorption
- Most drugs are excreted in the urine. Some are excreted in the faeces
- Biliary excretion important for drugs and metabolites of high molecular weight >350 kDa e.g. erythromycin. Often this is followed by loss of the drug in the faeces
- Minor routes: tears, sweat, saliva, breast milk
38
What is a drug half-life?
Amount of time required for the plasma concentration of a drug to decrease by 50% after discontinuance of the drug. Usually measured in hours.
39
What is absorption?
Movement of drug from administration site into systemic circulation/bloodstream
40
What is distribution?
Movement of drug around the body from the site of administration. Can be freeform (active) or bound to protein (inactive) but in equilibrium with the active form
41
What are the effect from drugs binding to receptors?
Either blocking or stimulating a response
42
What are agonists?
Drugs that bind to receptors and stimulate a response e.g. Beta 2 agonist
43
What are antagonists/blockers/inhibitors?
Drugs that bind to receptors and block a response e.g. calcium channel blockers
44
What can modify a drugs response?
Age, gender, body composition, genetics, placebo effect, physiological conditions, tolerance, diet and lifestyle
45
What do pharmacogenetics and pharmacogenomics do?
Examines genetics of an individual and their effect on drug therapy
46
What are various forms of metabolisms of drugs?
- Slow - not enough enzymes therefore metabolise slowly, causes prolonged half-life
- Normal
- Fast
47
What are drug vs food interactions?
Food can inhibit drug effect, affect drugs with narrow therapeutic window
48
What are drug vs drug interactions?
Affect drugs with a narrow therapeutic window, doesn't take much to cause toxicity or non therapeutic dosage which reduces opportunity for interactions
49
What are vulnerable groups in pharmacology?
- Pregnant women
- Older adults
- Paediatrics
50
What are issues of older adults in pharmacology?
- Have distribution, metabolism and excretion of drug affected, prolonged half life (drug stays in the body longer) which can lead to accumulation and toxicity therefore lower drug dosage and frequency
- Multiple conditions - associated polypharmacy
- Increased adverse effects from multiple drugs
- Non-compliance
51
What are issues of paediatrics in pharmacology?
Have distribution, metabolism and excretion of drug affected, prolonged half life which can lead to accumulation and toxicity therefore lower drug dosage and frequency
52
What are issues of pregnant woman in pharmacology?
- Try to avoid administering drugs due to the potential teratogenic effects on the fetus
- Drug movement into breast milk
53
What is a drug-receptor action?
The main mechanism of drug action usually involves a receptor
54
What drugs bind to an intracellular receptor?
- Non-steroidal anti-inflammatory drugs (NSAIDs)
- Nucleotide analogue Reverse Transcriptase Inhibitors (NRTI)
- Monoamine Oxidase Inhibitors
55
What do Non-steroidal anti-inflammatory drugs (NSAIDs) do?
Stop the synthesis of prostaglandin by blocking the enzyme needed for prostaglandin synthesis
56
What do Nucleotide analogue Reverse Transcriptase Inhibitors (NRTI) do?
Work specifically by blocking the action of the reverse transcriptase enzyme which is only present in viruses like HIV
57
What do Monoamine Oxidase Inhibitors do?
Used for depression and stops the enzyme monoamine oxidase from breaking noradrenaline down. Increased levels of noradrenaline promote our good wellbeing feeling
58
What is the most common way that drugs exert their action?
To chemically bind to a specific receptor within the body
59
How are receptors involved in adverse reactions?
Since receptors can be located all around the body
60
What are the two ways that drugs can work?
Either binding to a receptor (drug-receptor action) or producing a physiochemical action (Direct Physicochemical Action)
61
What drugs work via a simple chemical reaction?
Antacids and chelating agents
62
What are examples of physical mechanism for a drug reaction?
- Osmosis
| - Flatulence
63
What are the two drug actions that produce a physiochemical action?
- Simple chemical reaction
| - Physical mechanism
64
What is genetic polymorphism?
Refers to change in DNA sequence that occurs at an allele frequency of 1% or more in the general population
65
What is pharmacokinetic variation?
Genetic variants identified in many drug metabolising enzymes
66
What are examples of pharmacokinetic variations?
- CYP2C9
- CYP2C19
- CYP2D6
- CYP3A4
67
What does CYP2C9 do?
Responsible for metabolism of drugs including warfarin and verapamil, therefore introducing a risk of warfarin toxicity manifesting as potentially life-threatening haemorrhage
68
What does CYP2C19 do?
Actively involved in the metabolism of several drugs with the effects on the CNS
69
What does CYP2D6 do?
Involved in the metabolism of over 20% of all prescribed drugs
70
What does CYP3A4 do?
Involved in the metabolism of 50-60% of all prescribed medications, plays key role in the metabolism of several drugs used in the treatment of cancer.
71
What is pharmacodynamic variation?
Processes whereby effects of the drug are mediated; can reflect variation in binding of drugs to receptors
72
What are potential consequences of variants in drug metabolising enzymes?
- Increased plasma drug concentration and duration of action
- Decreased plasma drug concentration and therapeutic failure
- Adverse drug reactions/toxicity
- Failure to activate a prodrug
- Drug metabolism via alternate pathways
- Exacerbation of drug interactions
73
What will people with a high concentration of N-acetyltransferase be and what will the repercussions be?
- Fast acetylators
- Drugs will be acetylated and inactivated quickly and effectively
- Drug dosage may have to be raised to accommodate this.
74
What will people with a low concentration of N-acetyltransferase be and what will the repercussions be?
- Slow acetylators
- Drugs will be acetylated and inactivated slowly and this will lead to an accumulation of drug in the blood and possible toxicity
- Drug dosage may need to be altered
75
What is the placebo affect?
Effect elicited by administration of virtually any drug, whether it is pharmacologically active or not
76
What is a potentiation drug drug interaction?
When a drug drug interaction intensifies the effects of a drug
77
What is an inhibitory drug drug interaction?
When a drug drug interaction reduces the effects of a drug
78
What are possible effects of drug drug interactions?
Either increased therapeutic effects or increased adverse effects
79
What does contraindication mean for drugs?
Situation where a condition or other factor means that the use of the medicine should be avoided as the risk from use outweighs any therapeutic benefit
80
What does warning/precautions mean for drugs?
Situation where the benefits of using the medication may outweigh the risks, but it needs to be assessed on a case-by-case basis and the patient may need to be more closely monitored
81
What does onset of action mean?
Time taken to reach the minimum effective concentration (MEC) after a drug is administered
82
What does peak action mean?
When the drug reaches its highest blood or plasma concentration
83
What does duration of action mean?
The length of time the drug has a pharmacological effect
84
What is the pharmacokinetic effect for paediatrics?
- Impaired absorption
- Reduced metabolism
- Reduced excretion
85
What is the pharmacodynamic effect for paediatrics?
Drugs can have either a reduced or increased effect
86
Why are adverse drug reactions more common in elderly?
- Increased use of drugs; Polypharmacy
- Altered pharmacokinetics
- Altered pharmacodynamics
- Impaired homeostatic mechanisms
87
Why should pregnant woman takes drugs only if necessary?
Drugs may cross the placenta and affect the foetus
88
What can drugs taken in early pregnancy cause?
- Congenital malformations
| - Early miscarriage
89
What can drugs taken in later pregnancy cause?
- Growth retardation
- Prematurity – breathing difficulties
- May affect labour – premature, delayed or prolonged
- Pharmacological effect on foetus such as withdrawal or rebound effects after birth
90
What are definitions and examples of drugs that cure?
Administered over a set period of time to resolve issues
- Antibiotics
- Iron
91
What are definitions and examples of drugs that control?
Long term administration of drugs
- Insulin
- BP meds
- Antipsychotics
- Thyroid
92
What are definitions and examples of drugs that alleviate symptoms?
Drugs that manage symptoms
- Antacids
- Analgesias
- Antipyretics
- Antiemetics
- Anti-inflammatory
93
What is a type C (continuous) adverse reactions?
Effects of long-term treatment, removal of drug doesn't always remove adverse effects
94
What is a type D (delayed) adverse reactions?
Teratogenic effects on fetus
95
What is passive diffusion?
Movement from areas of high concentration to low concentration until reaching equilibrium
96
What is active diffusion?
Requires a carrier mediated transport
97
What affects absorption of drug?
- Administration route
- Drug characteristics
- Transit time
- Blood flow
- Surface area
- Pain, stress
98
What is the clinical importance of drugs?
- Drugs can affect binding of other agents/ molecules in the body e.g. bilirubin
- Drugs can compete for binding sites on proteins e.g. NSAIDs and warfarin
- Diseased state can affect protein levels and distribution of the drug e.g. cirrhosis of the liver
- Physiological state (e.g. pregnant; age of liver) can affect protein levels
99
What is an example of a drug with unchanged metabolism?
Gentamicin
100
What is an example of a drug that undergoes Phase I and II metabolism?
Diazepam
101
What is an example of a drug that undergoes Phase I only metabolism?
Theophylline
102
What is an example of a drug that undergoes Phase II only metabolism?
Morphine
103
What is an example of a drug that undergoes Phase II followed by Phase I metabolism?
Isoniazid
104
What is a prodrug?
A drug that is activated after entering the body e.g. simvastatin
105
What does increasing metabolising enzymes cause and how is medication managed due to this?
- Increased metabolism and decreased therapeutic effect
| - Increased dosage and/or frequency
106
What is extensive first pass effect and how is medication managed due to this?
- When majority of drug metabolised in liver with very little absorbing into systemic circulation
- Increased dosage and/or frequency
107
How many half lives does it usually take to achieve and lose the therapeutic effect?
5-6 half lives
108
What is therapeutic action?
End result of the drug action
109
What are various ways drugs work 'mode of action'?
- Chemical reaction
- Physical action
- Binding to a receptor
110
What is a chemical reaction?
Drugs work by a simple chemical reaction
111
What is a physical action of drugs?
Drugs can act by a physical mechanism
112
What is binding to a receptor?
Receptor is what a drug binds to cause a reaction or effect
113
How do adverse reaction occur when binding to receptors?
When the drug partially fits a receptor that was not targeted, invoking a unintentional reaction
114
What are other reasons for adverse effects?
- Drug action can work too well
- Drug not selective and binds to other types of receptors
- Genetic
115
What is the effect on drugs from fast metabolisers and how is this managed?
- Drug has less effect
| - Increased dosage and/or frequently
116
What is the effect on drugs from slow metabolisers and how is this managed?
- Drug has greater effect
| - Decreased dosage and/or frequently
117
What does individual variation mean?
One person can respond to the same drug differently to another person
118
What are factors involved in individual variation?
- Age
- Body weight and composition
- Gender
- Tolerance
- Pathological status
- Placebo effect
- Diet and lifestyle factors
- Non-compliance
- Genetics
119
What drug food interaction may have an impact on drug absorption?
Tetracycline and milk
120
What drug food interaction may have an impact on drug metabolism?
Grapefruit juice
121
What drug food interaction may have an impact on drug toxicity?
MAOI and tyramine-containing food
122
What drug food interaction may have an impact on drug action?
Broccoli and warfarin
123
What is potentiation?
- Increased therapeutic effect e.g. Augmentin
| - Increased adverse effects e.g. aspirin and warfarin
124
What is inhibition?
- Decreased therapeutic effect e.g. propranolol and terbutaline
- Decreased adverse effects e.g. morphine and narcan
125
How to reduce drug interactions?
- Non-pharmacological treatment
- Careful history taking
- Correct and appropriate dosage
- Frequent review of drug regimens
- Avoid poly-pharmacy if possible
- Keep drug regimen simple
126
Why are paediatrics sensitive to drugs?
Organ immaturity
127
Why are elderly sensitive to drugs?
Organ system degeneration
128
Why are pregnant woman sensitive to drugs?
Physiological changes and risk to foetus
129
What are examples of drugs pregnant woman may need to consume?
- Psychotics
- Pain relief
- Indigestion
- Constipation
- Antacids
- Gestational diabetes
- Antibiotics
130
What are teratogens?
Agents which cause malformations in foetus
131
What is the grading system for drug safety during pregnancy?
- Category A - No demonstrable risk
- Category B through D - Increasing risk
- Category X - Completely contraindicated during pregnancy
132
What is the percentage that relatively lowers risk of toxicity in breast milk?
Less than 10%
133
What do you assess when determining risk to infant from drugs in breastmilk?
- Concentration of drug in mothers milk
- Volume of milk ingested
- Bioavailability of drug
