Ethambutol Data - Uses, Dosage, Drug class, Brand name, Warnings, etc

Pharmacology	Ethambutol is a tuberculostatic agent active only against mycobacteria, including Mycobacterium tuberculosis and Mycobacterium avium complex (MAC). Does not directly enhance short-course (6–9 months) regimens with isoniazid, rifampin, pyrazinamide. Recommended in 4-drug initial regimen if drug resistance possible; continue for 12 months if isoniazid resistance confirmed. Used with clarithromycin for disseminated MAC in AIDS patients.
Adult Dosage	PO for active tuberculosis: - 15–25 mg/kg/day as a single dose - In combination with isoniazid, rifampin, and/or pyrazinamide PO for MAC infection: - 15 mg/kg/day (max 1 g/day) as a single dose - In combination with clarithromycin or azithromycin
Pediatric Dosage	Same as adult dosage: - Active tuberculosis: 15–25 mg/kg/day - MAC infection: 15 mg/kg/day (max 1 g/day)
Dosage Forms	- Tablet: 100 mg, 400 mg
Pharmacokinetics	Absorption: - ~80% from GI tract Peak Serum Concentration: - 2–6 mg/L (8–25 µmol/L) 2 hr post 15–25 mg/kg dose (adequate absorption) Half-life: - 4–6 hr; increases to 32 hr in severe renal impairment Excretion: - ~80% unchanged in urine
Adverse Reactions	Rare at 15–25 mg/kg/day. Rare: - Optic neuritis (blurred vision, color blindness, restricted visual fields); usually reversible with prompt discontinuation - Hyperuricemia (due to impaired uric acid excretion)