Isonicotinic acid hydrazide (INH)

Highly effective and most widely used antitubercular agent.



First- line drug for treatment of TB. Used for chemo prophylaxis of TB.

Adv. E

  1. Hepatotoxicity : Common in alcoholics, elderly people, rapid acetylators. Symptoms like anorexia, nausea, vomiting, and jaundice are seen. Reversible on discontinuation of drug.
  2. PERIPHERAL NEURITIS : Competitively interferes with utilization of pyridoxine due to structural similarity. Peripheral neuritis is common in slow acetylators.

Pyridoxine 10mg/day + INH is given to reduce risk

3. Other side effects : Fever, skin rashes, arthralgia, anemia, GI disturbances, psychosis and rarely convulsions.

INH inhibits metabolism of pheytoin, carbamazepine, warfarin etc. ➡️ increases plasma levels of these drugs ➡️ may result in toxicity.


Pharmacology 4th Ed: Tara V Shanbhag, Smita Shenoy

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