Pharmacology Basics Flashcards

Which route of drug administration completely bypasses first-pass hepatic metabolism?

Answer: Sublingual

Sublingual administration allows drug absorption directly into systemic circulation via the sublingual veins, completely bypassing first-pass hepatic metabolism.

The volume of distribution (Vd) of a highly lipophilic drug is expected to be:

Answer: Very large, distributed into fat tissues

Highly lipophilic drugs partition extensively into fatty tissues, resulting in a very large apparent volume of distribution.

An irreversible antagonist differs from a competitive antagonist in that it:

Answer: Decreases the maximum response (Emax) that can be achieved

An irreversible antagonist covalently or very tightly binds to the receptor, permanently reducing available receptors and lowering the achievable Emax.

CYP3A4 induction by rifampin would most likely result in:

Answer: Reduced efficacy of drugs metabolized by CYP3A4

Rifampin induces CYP3A4, accelerating the metabolism of co-administered CYP3A4 substrates and reducing their plasma concentrations and efficacy.

Which pharmacodynamic concept describes the concentration at which a drug produces 50% of its maximum effect?

Answer: EC50

EC50 (half-maximal effective concentration) is the drug concentration that produces 50% of the maximum pharmacological effect and reflects receptor potency.

Passive diffusion across a cell membrane is MOST dependent on which drug property?

Answer: Lipid solubility and degree of ionization

Passive diffusion is governed primarily by a drug's lipid solubility and its un-ionized fraction, as only non-ionized, lipophilic forms cross membranes readily.

Which statement about zero-order kinetics is correct?

Answer: A constant amount of drug is eliminated per unit time

Zero-order kinetics describes elimination of a fixed amount of drug per unit time regardless of concentration, seen when metabolic enzymes are saturated (e.g., ethanol, phenytoin at high doses).