Pharmacology · single question
A patient taking isoniazid (INH) for TB prophylaxis. What are the primary side effects?
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Correct answer: A. Hepatotoxicity and peripheral neuropathy (pyridoxine/B6 deficiency)
INH primary toxicities: (1) Hepatotoxicity — the most serious; LFTs must be monitored; (2) Peripheral neuropathy — caused by INH-induced pyridoxine (B6) depletion; pyridoxine (B6) supplementation is routinely co-prescribed to prevent this. Also: drug-induced lupus-like syndrome. INH is the most important drug for TB prevention/treatment.
- A. ✅ Hepatotoxicity + peripheral neuropathy (B6 deficiency) — the two major INH toxicities; B6 supplementation prevents neuropathy.
- B. ❌ Nephrotoxicity/ototoxicity = aminoglycosides (streptomycin, gentamicin) — not INH.
- C. ❌ QT prolongation is not a primary INH toxicity.
- D. ❌ Bone marrow suppression is not characteristic of INH toxicity.