Ethambutol (Myambutol)
First-line tuberculosis drug used in the RIPE regimen (Rifampin+Isoniazid+Pyrazinamide+Ethambutol). Inhibits arabinosyl transferase (EmbB), blocking arabinogalactan polymerization essential for mycobacterial cell wall synthesis. 80% renally excreted unchanged — dose adjust in renal impairment. Optic neuritis is the signature toxicity: dose- and duration-dependent, usually reversible if caught early. Baseline and monthly visual acuity/color vision testing required. Hyperuricemia from reduced urate clearance.
Projected serum levels — 800 mg, once daily
Maintenance schedule: 800 mg once daily (oral).
Modeled steady state after ~1 days: peak ≈ 143 mg, trough ≈ 3.6 mg body load. Population-based estimate over 15 days for a 800 mg dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.
Key facts
- Category
- Antitubercular
- Route modeled
- Oral
- Model confidence
- inferred
- Half-life
- 3.5 h
- Common dose
- 800 mg
- Suggested maximum
- 1.6k mg/day
- Reference dose range
- 400–1.6k mg (single dose)
- Suggested cadence
- once daily
- Validated against
- 800 mg oral — Cmax 3 mg/L at 3 h
Research behind this entry
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A controlled trial of 6 months chemotherapy in pulmonary tuberculosis: final report
Landmark BTS trial establishing the 6-month short-course RIPE regimen (2 months RIPE initial phase + 4 months rifampin+isoniazid continuation phase) with relapse rates <3%, revolutionizing TB treatment from 18+ months…
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Ocular toxicity of ethambutol: a meta-analysis of prevalence and risk factors
Meta-analysis establishing ethambutol ocular toxicity prevalence of ~1-2% at standard doses (15 mg/kg), escalating to 5-6% at higher doses, with duration-dependent risk. Most cases reversible if detected early by…
2 published studies referenced in the app, each with a plain-language summary.