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Test 1 - Lecture 2 Flashcards

1
Q

What are the “big three” ideal properties of a drug?

A
  1. Effectiveness - How well does it work?
  2. Safety - Remember there is no safe drug!
  3. Selectivity - The more selective the drug the better because it causes less side effects by hitting the right receptor. The size of the drug molecule, the shape of the molecule and the charge of the molecule effect the selectivity.
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2
Q

What is the therapeutic objective of a drug?

A

To provide the maximum benefit with minimal harm.

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3
Q

Why is it important for most drugs to be lipophilic as opposed to hydrophilic?

A

In order for a drug to directly penetrate a cell membrane it must be soluble in lipids.
Side Note: The smaller the molecule the better.

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4
Q

Where are drugs that are taken PO absorbed?

A

In the stomach and GI tract.

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5
Q

Pharmacotherapeutics

A

Defined as the achievement of the desired therapeutic goal from drug therapy - the desired outcome. It is the clinical purpose - the indication- for giving a drug.

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6
Q

Off label use

A

After a drug is approved, it is legally prescribed for a use that is not indicated on the label if the prescriber believes it to be of benefit.

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7
Q

T or F

Nurses are responsible for understanding the pharmcotherapeutics of all drugs that they administer.

A

True

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8
Q

Pharmacokinetics

A

The movement of the drug particles inside the body and the processes that occur during this movement.
pharmacon - drug or poison
kinesis - motion

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9
Q

What are the 4 phases of Pharmacokinetics?

A
  1. Absorption
  2. Distribution
  3. Metabolism (biotransformation)
  4. Excretion (elimination)
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10
Q

How does ionization effect drug effectiveness?

A

The charge of a drug molecule effects how easily it can go through cell membranes and bind to receptors.
Note:
1. Most drugs have no charge (non-polar).
2. Non-polar molecules are lipophilic.

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11
Q

T or F

Polar drug molecules are able to penetrate cell membranes.

A 
FALSE
Polar (charged) molecules are hydrophilic and CANNOT penetrate cell membranes.
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12
Q

What is the basic principal of a drugs action?

A

To modify existing functions within the body.

“No drug can be taken to grow a tail.”

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13
Q

Affinity

A

The attraction of the drug to the receptor - think of a magnet.

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14
Q

High affinity

A

Drug molecules bind to receptors at low drug concentration so a smaller dose is appropriate.

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15
Q

Low affinity

A

Drug molecules bind to receptors at a high drug concentration so a larger dose is appropriate.

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16
Q

Selectivity

A

The size, shape and charge of a molecule that determines whether it will bind to a receptor.

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17
Q

Absorption

A

The movement of a drug from route of administration into the bloodstream.
Note:
IV administration goes directly to blood and skips absorption.

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18
Q

Distribution

A

The movement of a drug through the bloodstream, into the tissues and eventually into the cells.

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19
Q

Metabolism (Biotransformation)

A

Transforming medicine from one substance to another.
This usually occurs in the liver but also occurs in the GI, kidney, lungs, brain and skin.
Usually goes from lipophilic to hydrophilic - The ability of a drug to become soluble in water is important because it allows the drug to be excreted through the renal system.

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20
Q

Excretion

A

Removes what the drug has become (metabolized into) and eliminates it from the body.
This occurs in the kidney.

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21
Q

Ion Trapping - also called pH portioning

A

When the pH on either side of a membrane differs, drug molecules tend to move to the side where ionization will occur. Once the molecules become ionized (charged - hydrophilic) they cannot move back through the membrane. Altering the pH on one side of the membrane alters the movement of the drug molecule.
An example is when the pH of urine is altered to pull an aspirin overdose out of the body.

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22
Q

Bioavailability

A

The fraction of a drug that is absorbed into the circulation after administration.
A bioavailability of 1 means that all of the given drug is available in the bloodstream. (scale is 0 to 1).
100% of a drug is absorbed
when given IV - bioavailability = 1.

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23
Q

Factors that effect absorption

A 
Bioavailability
Solubility - (lipophilic)
Surface Area - more SA = Greater absorption
Ionization = 0 charge
Blood flow - If circulation is compromised it is decreased
GI motility 
Age
Other medications
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24
Q

What drug route takes the longest to be absorbed?

A

PO -
They need to be broken down before they can enter the bloodstream.
The presence of other drugs or food may also impair the rate of oral drug absorption.

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25
What drug route is instantly absorbed?
IV - they are placed directly into the bloodstream.
26
T or F | Drugs given parenterally are absorbed quicker than drugs given orally.
True | They are already dissolved in a liquid form and therefore are absorbed more rapidly.
27
Factors that effect Drug Distribution
- Blood flow to the tissues. - Drugs ability to leave the blood. - Drugs ability to enter the cell. * ** The larger the drug molecule the harder it is to leave the blood or cross the cell membrane. - Protein Binding - Blood brain barrier - Placental membrane
28
What happens when a drug is bound to a protein?
It's unable to pass through the capillary walls. It impedes a drugs ability to reach sites of action, metabolism or excretion.
29
T or F | Once a drug is bound to a protein it stays there forever.
False | The bond dissolves in time and the drug molecules will become free and active again.
30
How are drug dosages calculated?
By the drug manufacturer based on the protein binding characteristics of the drug.
31
How does malnutrition, liver failure, or severe burns effect distribution of a drug?
The distribution of the drug is altered due to the lack of protein. When less drug is bound to protein, more drug is free and can be distributed to the site of action, thereby causing increased therapeutic (possibly toxic), and possibly increased adverse, effects.
32
What types of drug molecules are capable of moving to their site of action and achieving the desired therapeutic effect?
Unattached free molecules. The free drug is active as opposed to the protein bound drug.
33
Blood brain barrier
The purpose of the blood brain barrier it is to keep toxins and poisons from reaching the brain. Instead of wide spaces between the cells and the capillary walls the cells are packed tightly together. The tight junction is hard to penetrate so treating meningitis or other infections of the brain is a challenge. ***Neonates/Newborns are not as tight yet so have to be careful with them too.
34
Placental membranes
Any drug that can pass through a membrane can pass through the placenta. To pass through, a drug must be lipophilic, not ionized, and not protein bound. Everything Mom takes goes right to the fetus so need to exercise caution. Never give an X drug.
35
Does a high protein binding or low protein binding drug last longer in the bloodstream?
A high protein binding drug lasts in bloodstream longer.
36
Why are tube fed patients a concern when it comes to drug distribution?
They have more protein in their system which decreases the amount of active drug.
37
What will be the result of administering a high-protein bound drug to a patient with liver failure?
The drug will reach the target cells more quickly, which could result in a toxic effect.
38
Metabolite
A product of metabolism. Drugs that are metabolized are generally changed into an inactive form having no effect on the body as they travel throughout the body waiting to be excreted.
39
Prodrugs
Drugs that are inactive until metabolized into an active therapeutic form. Example: Primidone metabolizes into phenobarbital a strong anti-convulsant.
40
T or F | An active metabolite can cause a different and potentially harmful effect.
True | An example is meperidine - an analgesic that after metabolism turns into a neurotoxin.
41
T or F | An active metabolite can cause additional therapeutic effects.
True | An example is codeine metabolizing into morphine to provide additional pain relief to the patient.
42
First pass effect
PO drugs that that are absorbed through the G.I. tract and go into splenic vein and then onto the liver where they are metabolized and returned to the systemic circulation. The end result is a decreased amount of the drug available to act on the intended site - decreased effectiveness. Drugs that experience a high first pass effect may need a higher oral dose to achieve a therapeutic level of the circulating drug.
43
How do you avoid the first pass effect?
To avoid the first past affect or the need for high oral doses of a drug, drugs that are highly metabolized are often given by another route that bypasses the liver initially. For example: None of a drug given IV will initially go to the liver; all of it will return to the heart. From the heart slightly more than 25% of the drug will be sent to the liver where only a percentage of it is metabolized.
44
What system is predominantly responsible for liver metabolism?
P-450 (CYP) system (drug metabolizing enzymes)
45
What are the names of the 3 families involved in metabolizing drugs?
CYP1 CYP2 CYP3
46
What is the most common enzyme responsible for metabolism of most drugs?
CYP3A4
47
How do drugs effect the P-450 system?
They either induce or inhibit the P-450 system which alters the metabolism of other drugs.
48
What is a drug substrate?
Drugs metabolized by a CYP enzyme.
49
Drug Enzyme inhibitors
The drug inhibits the action of CYP isoenzymes responsible for drug metabolism and can contribute to toxic drug levels.
50
Drug Enzyme inducers
Drugs that induce a hepatic enzyme increase the amount of the enzyme present in the liver. When a large amount of this enzyme is available more metabolism can occur. Drugs that are metabolized by that enzyme are metabolized quicker and decrease the drug level more rapidly.
51
Name other factors effecting metabolism
1. Age - Elderly P-450 system generally reduced. Infants under 1 year P-450 system not well developed and liver doesn't function at 100% yet. 2. Genetics - Some people are "slow metabolizers" 3. Nutritional status - Liver relies on it! 4. Competition between drugs 5. Disease of the liver- Drugs stay in the bloodstream when liver is malfunctioning. 6. Pregnancy 7. Life Style - alcohol, smoking, supplements? 8. Food and Herbs - for example grapefruit is an inhibitor.
52
Most common route for drug excretion.
Urine | Also excreted through bile, expired air, breast milk, sweat and saliva.
53
What functions factor into elimination?
Kidney function Liver function Blood flow to organ of elimination
54
What factors effect excretion?
Renal Clearance pH dependant ionization -An example is when the pH of urine is altered to pull an aspirin overdose out of the body. Competition for active tubular transport Age
55
What processes are involved in renal excretion?
1. Glomular filtration 2. Tubular reabsorption (passive) 3. Tubular secretion (active)
56
Glomular filtration
Most drugs pass easily through the spaces of the capillary walls into the urine in the proximal tubule. Only very large particles, such as proteins, cannot pass. Drug molecules bound to protein will therefor not be filtered.
57
Tubular reabsorption (passive)
If the drug has not been changed by metabolism into a form that is not lipid soluble (hydrophilic) passive tubular reabsorption cannot occur. Instead, the drug remains in the urine and is excreted. They need to be hydrophilic once they get into the kidney to be excreted.
58
Tubular secretion (active)
Active transport systems in the renal tubule work to move some drugs from the blood and into the urine.
59
Factors effecting excretion
Renal clearance Ph dependant ionization Competition for active tubular transport Age
60
Ph dependant ionization
Drug excretion can be increased if the pH of the urine encourages the drug to be an ion. If another drug or some other agent is introduced that makes the urine more basic, acidic ions will be ionized and excreted in the urine. Drug overdose is treated this way.
61
Competition for active tubular transport
When 2 drugs compete for a space in the active transport system for excretion, the transport system becomes overloaded. Some of the drug particles remain in the blood until they can be moved by the transport system. This residual portion will increase the circulating time of active drug in the body and slow the excretion of both drugs.
62
Bile excretion
Bile is circulated back to the liver which allows the drug to stay in the system a few times which increases the half life of the drug and prolongs the duration of action.
63
What is the main concern regarding the elderly and pharmacy?
They are at risk for toxicity.
64
Half-Life
The amount of time that is required to remove half (50%) of the blood concentration of a drug. Half lives vary based on their pharmacological properties. Half life is represented by t 1/2 =
65
Steady state
The point at which the amount of the drug being administered and the amount being eliminated are equal.
66
TEST QUESTION: | How many half-lives does it take to achieve steady state?
At 4 to 5 half lives steady state is acheived.
67
Does increasing a dose have any effect on how quickly steady state is acheived?
No - it occurs in 4 to 5 half lives regardless of the dose..
68
When is the full pharmacotherapeutic response of a drug measured?
When it reaches steady state.
69
If you only take 1 dose of a medicine, when is steady state acheived?
In 4 to 5 half lives.
70
If a patient has liver or renal disease, should the dosage of a drug be adjusted?
Yes - a decreased dose is needed for most drugs because it stays in the system longer.
71
Pharmacodynamics
Action of a particular drug within the body and the study of how those actions occur....How the drug effects the body
72
Drug Action
How the drug works
73
Drug effect
Persons response to a drug's action.
74
Can drugs create a new response in the body?
No | They can only turn on, turn off, promote, or block a response that the body is inherently capable of producing.
75
How do most drugs produce their effect on the body?
They attach to receptors where they can stimulate the cell to act in a way that the cell is designed to act. They either block or speed up an enzyme.
76
What are the 2 types of drug receptor interactions?
Agonist - A drug that attaches to a receptor to promote a function. Antagonist - A drug that attaches to a receptor and prevents something else from attaching and causing an effect.
77
3 types of antagonists
Competitive - lots of drugs compete to get on the receptor Irreversible - Anti-coagulent Chemical - Bind to another drug to change shape so it cant go to the receptor
78
2 types of agonists
partial - only bind to a partial portion of a receptor | full - binds 100% to a receptor
79
Minimum effective Concentration (MEC)
A certain level of drug must be present in the body to produce an effect at all - this level is the MEC.
80
Potency
The amount of a drug that must be given to produce a particular response. A drug that is highly potent requires less of the drug to produce its effect. Amount needed to get therapeutic effect.
81
Efficacy
This is how well a drug produces its desired -therapeutic- effect.
82
Maintenance dose
A dose administered consistently over time which maintains steady state.
83
Loading dose
Larger than usual dose to reach therapeutic effect quicker.
84
Onset of action
How long it takes a drug to work.
85
Duration of action
How long the drug stays in the therapeutic range.
86
Therapeutic Range
This is where the drug concentration is above the MEC and below the level at which adverse effects occur. Where its working and doing what it is supposed to do.
87
Narrow therapeutic range
Drugs that have a narrow therapeutic range do not have much difference between the effective dose and the toxic or lethal dose. Patients need to be monitored closely for adverse effects and have their blood levels monitored closely.
88
T or F | All drugs have some type of adverse effect.
True
89
The difference between adverse effect and side effect
Adverse reactions are unexpected or unintended. Side effects are expected and unavoidable secondary drug effects produced at the therapeutic level.
90
Predictable adverse responses
Side effects Toxic effects Cumulative effects - rate of administration exceeds rate of biotransformation or elimination
91
Unpredictable adverse responses
Idiosyncratic - The opposite of what was expected. Example: Benadryl makes most people sleepy but some hyper. Allergic Reaction Anaphylactic Reaction
92
Iatrogenic Responses
A response due to a physician (provider) error.
93
Drug to drug interaction
Change in magnitude or duration of a response to one drug in the presence of another drug. Can be related to the pharacokinetic or the parmacodynamic characteristics of a drug.
94
Additive effect
2 or more like drugs are combined. 1(drug A) + 1(drug B) = 2 Alcohol and aspirin combined cause increased risk for GI bleeding.
95
Synergistic effect
2 or more unlike drugs are combined. 1(drug A) + 1(Drug B) = 3 Diuretic and BP Med combined to treat hypertension
96
Potentiation effect
1 drug is enhancing the effectiveness of the other drug. 1/2(Drug A) + 1(Drug B) = 2 Vitamin D helps with absorption of calcium.
97
Antagonist Effect
2 drugs taken together cancel out each other. 1(Drug A) + 1(Drug B) = 0 Narcan and Morphine
98
The nurse knows that an antagonist is a type of drug that:
Has affinity for a receptor but little efficacy.

Pharm (11 decks)

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