Ethambutol
MYAMBUTOL
Pronunciation: e-THAM-byoo-toel
What it isInhibitor of mycobacterial arabinosyl transferase; tuberculosis.
Why this oneIt is included to prevent resistance emerging while susceptibility is pending.
What limits it⚑ Dose-related optic neuritis impairs red-green discrimination; check acuity and color vision. Renal impairment requires adjustment.
FDA-approved for
- pulmonary tuberculosis
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Tuberculosis — initial treatment (no prior therapy) | adult | 15 mg/kg QD | 15 mg/kg QD | 15 mg/kg QD |
| Tuberculosis — retreatment | adult | 25 mg/kg QD | decrease to 15 mg/kg QD after 60 days | 25 mg/kg QD |
Renal Undefined
Hepatic Undefined
Instructions
- Single oral dose once every 24 hours
- May give with food (absorption not significantly altered)
- Never use alone — combine with >=1 other antituberculous drug
- Monthly eye exams while on 25 mg/kg
Available strengths
- tab 100, 400 mg
Contraindications
- Known optic neuritis (unless clinical judgment permits)
- Patients unable to appreciate/report visual changes (young children, unconscious)
Cautions
- Optic neuropathy/neuritis — decreased visual acuity, may be irreversible; monitor visual acuity before and periodically (monthly at >15 mg/kg/day)
- Not recommended under 13 years of age
Adverse reactions
- Decreased visual acuity / optic neuritis (incl. irreversible blindness)
- Scotoma, color blindness, visual field defect
Pregnancy Category C; ophthalmic abnormalities reported in exposed infants; use only if benefit justifies risk.
Lactation Undefined
Cost
Generic entry1999
NO BOXED WARNINGS
Principal riskDose-related optic neuritis; check color vision
Classes and tags
Clinical profile
Legacy pregnancy categoryUnknown / historical label unavailable
Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.