Section 15 · Monograph
Ethambutol
Reviewed Nov 2026FDA label
MyambutolAntimycobacterial
- Forms
- Tab: 100, 400mg
- Dose
- TB meningitis: 15-20mg/kg/day (max about 1.6g) in the intensive phase
- MOA
- Inhibits arabinosyl transferase (cell wall synthesis)
Indications
- Pulmonary and extrapulmonary tuberculosis (in combination)FDA-labeled
Mechanism of Action
- Inhibits arabinosyl transferases involved in mycobacterial cell wall synthesis; bacteriostatic
Full Dosing
Adult / usual
- Typically stopped when susceptibility to isoniazid and rifampin is confirmed
- Take once daily; aluminum antacids reduce absorption
Renal
- 15-20mg/kg/day PO (max about 1.6g) in the intensive phase; renal dose adjustment
Contraindications
- Known optic neuritis
- Patients unable to report visual changes (infants or unconscious patients)
- Hypersensitivity
Drug Interactions
- Aluminum-containing antacids reduce absorption
- Other neurotoxic drugs (linezolid, isoniazid) add to neuropathy and optic neuropathy risk
Adverse Effects
- Dose-related optic neuritis (reduced acuity, red-green color blindness)
- Peripheral neuropathy
- Hyperuricemia
- Rash
Monitoring Parameters
- Baseline and monthly visual acuity and color discrimination
- Renal function
- Neuropathy symptoms
Pregnancy & Lactation
- Considered safe in pregnancy
- Compatible with breastfeeding