Pharmacology Fundamentals Flashcards

Which pharmacokinetic parameter describes the fraction of an administered dose that reaches systemic circulation unchanged?

Answer: Bioavailability

Bioavailability (F) is the fraction of administered drug that reaches systemic circulation in unchanged form.

A drug with a narrow therapeutic index requires more careful dosing because:

Answer: The toxic dose is close to the therapeutic dose

A narrow therapeutic index means there is little difference between the minimum effective concentration and the minimum toxic concentration.

Which type of drug-receptor interaction is characterized by a drug that binds to a receptor and produces a submaximal effect even at full receptor occupancy?

Answer: Partial agonist

A partial agonist activates receptors but produces a lower maximal effect (Emax) than a full agonist, even at 100% receptor occupancy.

First-pass metabolism most significantly affects drugs administered by which route?

Answer: Oral

Orally administered drugs pass through the portal circulation to the liver before reaching systemic circulation, where extensive first-pass metabolism can significantly reduce bioavailability.

The ED50 of a drug refers to the dose that produces the desired effect in:

Answer: 50% of the test population

ED50 is the effective dose that produces the desired therapeutic response in 50% of the population studied.

Cytochrome P450 enzyme induction by a co-administered drug is most likely to result in:

Answer: Reduced plasma levels of the substrate drug

Enzyme induction increases the rate of metabolism of substrate drugs, leading to lower plasma concentrations and potentially reduced therapeutic effect.

Which term describes the phenomenon where repeated drug administration leads to a diminished pharmacological response over time?

Answer: Tachyphylaxis

Tachyphylaxis is the rapid development of tolerance to a drug's effects following repeated administration in a short time period.