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Didactic Year > Receptor Pharmacology, Pharmacokinetics, Pharmacodynamics > Flashcards

Receptor Pharmacology, Pharmacokinetics, Pharmacodynamics Flashcards

1
Q

Pharmacology

A

Study of drugs and their interactions with the human body

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2
Q

Drug

A

Any chemical agent that affects the living part of a cell

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3
Q

Adverse Drug Reaction (ADR)

A

Response to a drug that is harmful and unintended. (sometimes we use drugs such as “benadryl” for insomnia, rather than it’s intended purpose as an antihistamine)

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4
Q

Pharmacokinetics

A

Action of the body on a drug. The study of the fate of drugs. The absorption, distribution, metabolism (biotransformation), and elimination of drugs.

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5
Q

Understanding pharmacokinetics can

A

Increase the probability of therapeutic success and reduce the occurrence of adverse drug effects

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6
Q

we use pharmacokinetics to determine

A

The proper drug to use, route of administration, dosing schedules

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7
Q

Absorption of drugs

A

Movement of a drug from its site of administration into circulation and the extent to which it occurs

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8
Q

Solid dosage absorption requires

A

Dissolution of the tablet or capsule

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9
Q

Ways absorption can occur

A

Via active (against concentration gradient with energy), or passive (from higher to lower concentration) diffusion.

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10
Q

Drug interactions commonly occur during

A

Movement through the gi tract (food, etc.)

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11
Q

Bioavailability (F) of drugs

A

The fractional extent to which a dose of drug reaches its site of action

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12
Q

Factors that decrease bioavailability

A

Gi absorption, hepatic first pass effect/metabolism

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13
Q

Hepatic first pass effect

A

Pre systemic metabolism. The drug passes through the liver the first time and is nearly gone: high first pass rate

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14
Q

Places a drug in circulation can go

A

The therapeutic site of action, or unwanted sites of action

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15
Q

We can bypass gut absorption issues with

A

IV formulations

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16
Q

Distribution of drugs

A

Occurs after absorption, when the drug is transported to a site where it reacts with various bodily tissues and/or receptors

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17
Q

The rate of drug delivery is determined by

A

Cardiac output, regional blood flow, capillary permeability, and tissue volume

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18
Q

What areas initially receive most of the drug?

A

Liver, kidney, brain, and other well perfused organs.

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19
Q

Second distribution phase

A

Slower than first. Delivers to muscle, most viscera, skin, fat. Involves a far larger fraction of body mass.

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20
Q

What limits concentrations of free drug

A

Binding of drug to plasma proteins and tissue macromolecules

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21
Q

Determinants for distribution

A

Lipid solubility and transmembrane pH

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22
Q

Prolonged drug affects occur with

A

Lipid soluble drugs, stored in adipose tissue with low blood flow. (highly lipid soluble drugs include benzodiazepines, barbiturates, phenothiazines)

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23
Q

Metabolism of drugs

A

Mainly occurs in the liver. Body converts active lipid soluble compounds to inactive water soluble substances to be primarily excreted by the kidneys

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24
Q

What is phase I of drug metabolism?

A

Hepatic microsomal enzymes oxidize, demethylate, and hydrolyze drugs. (drugs with short half lives and inactive metabolites are almost entirely during first pass)

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25
Q

Phase 2 of drug metabolism?

A

Large water soluble substances are attached to the drug. (compounds may circulate through one or both phases multiple times until water soluble characteristics are present)

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26
Q

Do more drug interactions occur during phase I or 2 of drug metabolism?

A

Phase 1 (more DI’s are caused by phase 1 hepatic enzymes)

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27
Q

Hepatic microsomal enzymes

A

Important group in phase 1, characterized by cytochrome P450 isoenzymes. More commonly induced/inhibited by other drugs. (numerous forms)

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28
Q

CYP450 System

A

Is responsible for the oxidation of many drugs

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29
Q

What affect do drugs have on CYP metabolism?

A

Drugs can act as substrates, inhibitors, and inducers of this metabolism

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30
Q

Which CYP families are primarily involved with drug metabolism?

A

CYP families 1,2,3, and 4

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31
Q

Enzyme inhibitors

A

Decrease the rate of metabolism of object drug by obstructing metabolizing enzyme

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32
Q

Inhibition of an enzyme causes

A

Increased drug concentration, increased half life, accumulation, and can lead to toxicities

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33
Q

Enzyme induction

A

Stimulates the increase of cyp450 enzyme activity. Increases clearance of drug

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34
Q

What is the prototype inducer?

A

Phenobarbital

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35
Q

Drug excretion/elimination

A

Process that removes drug and its metabolites from the body. (primarily through the urine)

36
Q

Excretory organs eliminate polar compounds more efficiently than

A

Substances with high lipid solubility

37
Q

Lipid soluble drugs are only readily eliminated once they are

A

Metabolized to more polar compounds

38
Q

What is the most important organ for excretion?

A

The kidneys

39
Q

Substances excreted in feces are

A

Principally unabsorbed orally ingested drugs or drug metabolites

40
Q

Anesthetic gas is excreted through

A

The lungs

41
Q

Factors affecting pharmacokinetic principles

A

Age, sex, weight, disease states, genetic factors (all 4 principles can vary from pt to pt)

42
Q

Pharmacodynamics

A

Action of the drug on the body. The study of the biochemical and physiological effects of drugs and their mechanisms of actions. (can provide the basis for the rational therapeutic use of a drug)

43
Q

What are the most common mechanisms for drug interactions?

A

Synergism, antagonism, altered cellular transport, and effects on receptor sites.

44
Q

Four most important parameters governing drug disposition are

A

Bioavailability, volume of distribution, clearance, and elimination

45
Q

Volume of distribution

A

Relates the amount of drug in the body to the concentration of drug in the blood or plasma depending on the fluid measured.

46
Q

Half life

A

The time it takes for the plasma concentration to be reduced by 50%.

47
Q

Steady state

A

Amount of drug administered in a given period (maintenance dose) is equal to the amount in the eliminated in that same period. ( Rate in = rate out )

48
Q

Approximate how long does it take to reach steady state

A

About 5 half lives

49
Q

Classifications of drug interactions

A

Can be pharmacokinetic or pharmacodynamic

50
Q

Types of drug interactions

A

Drug-drug, drug-food, drug-disease

51
Q

Pharmacokinetic DIs

A

Occurs when ADME of one drug is affected by another drug/agent

52
Q

Absorption drug interactions

A

Can occur in the gi, due to ph, chelation, increase or decrease in motility, or changes in the GI flora.

53
Q

Distribution drug interactions

A

Drugs bound to proteins, “free” unbound drugs are active

54
Q

Metabolism drug interactions

A

CYP450 inducers include cigarette smoking and phenytoin, and CYP450 inhibitors include grapefruit juice and erythromycin

55
Q

Elimination drug interactions

A

Ex: competition can occur between two drugs over elimination. In the case of probenecid and penicillin, probenecid is excreted first. This causes an increased concentration of penicillin due to decreased elimination.

56
Q

Synergistic effects

A

Also known as additive effect, example is beer and Valium

57
Q

Antagonistic effects

A

Opposing effects, work against each other (2+2=1)

58
Q

Potentiation/synergism

A

Interaction between 2 or more drugs creating a pharmacologic response greater than the sum of the individual drugs (1+1=5)

59
Q

Receptor

A

Molecule to which a drug binds to bring about a change in function of biologic system

60
Q

Receptor site

A

Specific region of receptor molecule where drug binds

61
Q

Inert binding molecule

A

A molecule to which a drug can bind without changing any function

62
Q

Max efficacy

A

Maximum effect that can be achieved with a particular drug regardless of dose

63
Q

Potency

A

The amount of drug needed to produce a given effect (determined by affinity of receptor for the drug and number of receptors)

64
Q

ED50

A

Dose that causes 50% of maximum effect

65
Q

TD50

A

Median toxic dose, dose where toxicity occurs in 50% of cases

66
Q

LD50

A

Median lethal dose, dose where death occurs in 50% of cases

67
Q

Therapeutic index (TI) subtracted by TD50

A

Equals ED50

68
Q

Agonist

A

A drug that activates its receptor upon binding

69
Q

Partial agonist

A

Drug that binds to receptor but produces a smaller effect at full dosage than a full agonist

70
Q

Allosteric agonist

A

Drug that bind to the receptor molecule without interfering with normal agonist binding. They also alter the response with normal agonist

71
Q

Antagonist

A

Drug binds without activating its receptor and preventing activation from an agonist

72
Q

Competitive antagonist

A

Pharmacologic antagonist that can be overcome by increasing the concentration of agonist

73
Q

Irreversible antagonist

A

Cannot be overcome by increasing agonist concentrations, “irreversibly” binds to the receptor site

74
Q

Physiologic antagonist

A

Drug that counters the effect of another by binding to a different receptor and causing opposing effects

75
Q

Chemical antagonist

A

Drug that counters the effect of another by binding to the agonist drug (not the receptor)

76
Q

Allosteric antagonist

A

Binds to receptor molecule without interfering with normal antagonist binding but alters response to binding

77
Q

Signaling

A

Once an agonist drug has bound to its receptor, some effector mechanism is activated. Drug-receptor interactions, 5 major types

78
Q

Receptor regulation

A

Regulated in number, location, and sensitivity. Changes can occur over minutes or days

79
Q

Tachyphylaxis

A

An acute decrease in the response to a drug after its administration. (Frequent or continuous exposure to agonists resulting in short term reduction of receptor response)

80
Q

Receptor downregulation

A

Long term reductions in receptor number which occur in response to continuous to agonists

81
Q

Receptor upregulation

A

Increases in receptor number when receptor activation is blocked for prolonged periods by antagonists

82
Q

Receptor-Effector systems

A

Enzyme in intracellular space
Neurotransmitter reuptake transporters
Voltage-activated ion channels

83
Q

Transmembrane enzymes

A

Drug binds to extracellular component to activate an enzymatic reaction in the intracellular component (outer domain = receptor, inner domain = effector)

84
Q
A
85
Q
A
86
Q
A

Didactic Year (24 decks)

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