Pharmacology · single question
A patient is taking Isoniazid (INH) for tuberculosis. What is the most important side effect to monitor?
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Correct answer: C. Hepatotoxicity (drug-induced hepatitis)
Isoniazid (INH) is a first-line anti-TB drug whose most significant adverse effect is hepatotoxicity/drug-induced hepatitis. It can cause elevated liver enzymes (ALT, AST), and rarely fulminant hepatic failure. Risk increases with age, alcohol use, and concurrent use of rifampin. Peripheral neuropathy (from pyridoxine/B6 depletion) is another major side effect, managed by concurrent B6 supplementation.
- A. CORRECT. Hepatotoxicity is the most clinically important side effect of isoniazid. Liver function tests must be monitored during TB therapy.
- B. Incorrect. Nephrotoxicity is not a primary concern with INH. Drugs like aminoglycosides (streptomycin) are nephrotoxic.
- C. Incorrect. Ototoxicity is associated with aminoglycosides and cisplatin, not isoniazid.
- D. Incorrect. Cardiotoxicity is not a known significant effect of isoniazid therapy.