Pharmacology Fundamentals Flashcards

A patient on MAO inhibitors eats tyramine-rich food. Which pharmacological interaction explains the resulting hypertensive crisis?

Answer: Reduced tyramine breakdown leads to massive norepinephrine release

MAO normally degrades tyramine; when inhibited, tyramine accumulates and triggers massive norepinephrine release causing severe hypertension.

Which statement best describes an inverse agonist?

Answer: A drug that binds a receptor and produces the opposite effect to the natural agonist

Inverse agonists bind to the same receptor as agonists but stabilize it in an inactive conformation, producing an effect opposite to the agonist.

A drug undergoes enterohepatic recirculation. What is the clinical consequence of this process?

Answer: Prolonged drug action due to repeated reabsorption from the gut

Enterohepatic recirculation allows drugs excreted in bile to be reabsorbed from the intestine, prolonging their half-life and duration of action.

When calculating drug loading dose, which pharmacokinetic parameter is most critical?

Answer: Volume of distribution

Loading dose = target concentration × volume of distribution (adjusted for bioavailability), so Vd is the key determinant.

A patient's renal drug clearance equals the GFR without any tubular secretion or reabsorption. Which substance behaves this way and serves as its marker?

Answer: Inulin

Inulin is freely filtered and neither secreted nor reabsorbed, making its clearance equal to GFR and the gold standard for measuring GFR.

Phase II drug metabolism primarily involves:

Answer: Conjugation reactions that increase water solubility for excretion

Phase II metabolism involves conjugation (glucuronidation, sulfation, acetylation, glycine conjugation) that makes drugs more water-soluble for excretion.

A drug with pKa of 4 is administered orally. In the acidic stomach (pH 1), it will predominantly exist in which form?

Answer: Unionized (non-polar) form, enhancing gastric absorption

An acidic drug with pKa 4 in pH 1 environment is predominantly unionized (Henderson-Hasselbalch: pH < pKa favors unionized weak acids), enhancing membrane permeability.