Pharmacology definitions

Question 1

Bioavailability

Answer 1

the fraction of administered drug that reaches the

systemic circulation in an unchanged form

Question 2

Drug half-life

Answer 2

amount of time required for the plasma concentration of a drug to decrease by 50% after discontinuation of a drug.

Question 3

Efficacy

Answer 3

refers to the degree to which a drug is able to induce maximal therapeutic effects. Efficacy is a term often used to compare drugs of different classes.

Question 4

Potency

Answer 4

is the amount of drug required to produce 50% of the maximal response thatthe drug is capable of inducing. Potency is a term more frequently used to compare drugs of a similar class.

Question 5

EC50

Answer 5

effective concentration 50 is theconcentration or dosage of an agent which induces a specified clinical effect in 50% of the subjects to which the drug has been administered.

Question 6

LD50

Answer 6

lethal dose 50 is the concentration or dosage of an agent or drug which causes death in 50% of the subjects to which that agent or drug has been administered.

Question 7

Therapeutic index

Answer 7

ratio of the dose of a drug that produces toxicity
relative to the dose of the same drug that produces a clinically desired response.
Looked at as an equation, this would be
T.I. = LD50 / EC50

Question 8

DEA guideline for drug use in pregnancy

Answer 8

• A – Controlled studies show no risk.
• B – No evidence of risk in humans.
• C – Risk cannot be ruled out.
• D – Positive evidence of human fetal risk.
• X – Contraindicated in pregnancy.