Drug Excretion · Pharmacology

The use of Probenecid to prolong the half-life of Penicillin is based on which mechanism?

  1. Inhibition of glomerular filtration of the drug
  2. Enhancement of passive tubular reabsorption
  3. Inhibition of hepatic drug metabolism
  4. Competitive inhibition of tubular secretion
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Correct answer: Competitive inhibition of tubular secretion

Probenecid competes with Penicillin for the organic anion transporters (OAT) in the proximal tubule. By blocking the secretion of Penicillin into the tubular lumen, Probenecid decreases its renal excretion and extends its duration of action.

Difficulty: Medium Question 5 of 20

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