Generic Name and Formulations:
Isoniazid 100mg/mL; soln for IM inj; contains chlorobutanol.
Treatment and prophylaxis of susceptible tuberculosis.
Treatment: 5mg/kg up to 300mg daily in a single dose; or 15mg/kg up to 900mg/day, 2 or 3 times/week. See literature for regimens in patients with pulmonary TB without HIV, pulmonary TB with HIV, patients with extra pulmonary TB, pregnant women with TB, and patients with multi-drug resistant TB. Prevention: >30kg: 300mg/day in a single dose. Malnourished, predisposed to neuropathy: give concomitant pyridoxine.
Treatment: 10–15mg/kg up to 300mg daily in a single dose; or 20–40mg/kg up to 900mg/day, two or three times/week. See literature for regimens in patients with pulmonary TB without HIV, pulmonary TB with HIV, patients with extra pulmonary TB, pregnant women with TB, and patients with multi-drug resistant TB. Prevention: 10mg/kg (up to 300mg daily) in a single dose. Malnourished, predisposed to neuropathy: give concomitant pyridoxine.
Drug-induced hepatitis. Previous isoniazid-associated hepatic injury. Severe adverse reactions to isoniazid (eg, drug fever, chills, arthritis). Acute liver disease of any etiology.
Increased risk of severe or fatal hepatitis; monitor, discontinue if signs of hepatic damage detected. Defer in acute hepatic disease. Alcoholics. Chronic liver disease. Perform LFTs prior to therapy, then periodically as needed. Severe renal dysfunction. >35yrs old. Peripheral neuropathy or conditions predisposing to neuropathy. Injection drug use. Women belonging to minority groups, particularly in the post-partum period. HIV seropositive. Perform eye exams if visual symptoms occur. Neonates. Pregnancy (Cat.C). Nursing mothers.
Concomitant hepatotoxic agents: may cause fatal liver dysfunction. Concomitant alcohol may be associated with higher incidence of isoniazid hepatitis. Monitor prothrombin time with concomitant anticoagulants. May potentiate phenytoin, carbamazepine, theophylline, valproate (adjust dose). May antagonize ketoconazole. May inhibit assays for serum folate and Vit. B12 (consider alternative methods).
Peripheral neuropathy (esp. in slow acetylators), elevated serum transaminases (SGOT; SGPT), bilirubinemia, bilirubinuria, jaundice, hepatitis (may be fatal), nausea, vomiting, epigastric distress, pancreatitis, blood dyscrasias, hypersensitivity reactions (eg, skin eruptions, TEN, DRESS), pyridoxine deficiency, hyperglycemia, pellagra, metabolic acidosis, gynecomastia, rheumatic syndrome, SLE-like syndrome, inj site reactions.
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