Isoniazid Dosage in Patients with Renal Failure

ALTHOUGH isoniazid has been used in antituberculous therapy for 20 years, the influence of renal failure on isoniazid excretion has never been established. Paradoxically, this gap in medical knowledge continues despite expanded indications for the use of the drug in patients with renal failure. For example, the American Thoracic Society ad Hoc Committee on chemoprophylaxis has included tuberculin-positive patients with a variety of chronic renal diseases in their recommendations for isoniazid prophylaxis.1 In patients with normal renal function 50 to 80 per cent of a dose of isoniazid is excreted in the urine in 24 hours.2 3 4 5 Part of the drug . . .