Ethanol
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Drug reference
ethionamide
Second-line antitubercular (thioamide) · Antituberculosis
START
250 mg PO once daily, titrate to 500–1000 mg/day in divided doses with food
TYPICAL MAX
1 g/day
STOP IF
Significant hepatitis, psychosis, optic neuritis, or peripheral neuropathy
WATCH
LFTs (monthly), TSH (q6m), glucose, mood, vision; pyridoxine 50 mg/day to prevent neuropathy
CDSCO approvedATC J04AD03
KDIGO 2024 + manufacturer label
- ONSET
- 1h · absorption
- PEAK
- 2h · Tmax
- t½
- 2.5h · t½
- DURATION
- 8h · divided dosing
EXCRETION
Renal — mainly metabolites
route + CYP
INTERACTIONS
7 major
SEVERE in our sources
PREGNANCY
Avoid unless essential — animal teratogenicity (CNS).
FDA category + note
Top interactionssee all 12 →
- EthanolSevereDatabaseDDInter
- LeflunomideSevereDatabaseDDInter
- LomitapideSevereDatabaseDDInter
- MipomersenSevereDatabaseDDInter
Mechanism
Prodrug activated by mycobacterial EthA (FAD-monooxygenase) to a form that inhibits InhA (enoyl-acyl-carrier-protein reductase) — blocking mycolic-acid synthesis; cross-resistant with isoniazid via inhA mutation but not katG.
Indications
Multidrug-resistant tuberculosis (combination)Other mycobacterial infections (selected, specialist)
Dosing
- Adult
- Starting 250 mg PO once daily, titrate up over days to 500–1000 mg/day in divided doses with food (max 1 g/day); 15–20 mg/kg/day.
- Pediatric
- 15–20 mg/kg/day in 1–2 divided doses (max 1 g/day).
- Renal adjustment
- Caution in severe impairment; usually no fixed adjustment.
- Hepatic adjustment
- Avoid in severe disease; monitor LFTs.
- Geriatric
- Lower doses; hepatic/psychiatric risk.
- Max dose
- 1 g/day
Pharmacokinetics
Onset
Antimycobacterial effect over days
Peak effect
~2 h (Tmax)
Duration
~8 h
Half-life
~2–3 h
Bioavailability
~80% (oral; food can reduce nausea)
Protein binding
~30%
Metabolism
Hepatic (active sulfoxide metabolite)
Excretion
Renal (mainly metabolites)
Contraindications
- Severe hepatic impairment
- Hypersensitivity to thioamides
- Caution: pre-existing psychiatric illness, diabetes (hypoglycaemia/altered control), hypothyroidism
Side effects
Common
Nausea/vomiting (very common)Metallic tasteAnorexiaHepatic enzyme riseDizzinessHypothyroidism
Serious
- Hepatotoxicity (significant)
- Psychiatric disturbance (psychosis, depression)
- Peripheral neuropathy
- Hypoglycaemia / glycaemic disturbance
- Goitre / hypothyroidism
- Optic neuritis
Pregnancy & lactation
Pregnancy
Avoid unless essential — animal teratogenicity (CNS).
Lactation
Avoid; limited data.
Drug interactions
Leflunomide
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Lomitapide
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Mipomersen
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Pexidartinib
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Rifampicin
Severe
Database
Drug interaction classified as: synergy.
Source: DDInter
Teriflunomide
Severe
Database
Drug interaction classified as: synergy
Source: DDInter
Levothyroxine
Moderate
Textbook
Increased levothyroxine dosage requirements.
May require increased levothyroxine dosage.
Source: G&G 14e
Cycloserine
Moderate
Database
Additive CNS toxicity
Monitor mood/seizures
Source: Kimi deep-research + Cla
Alcohol
Moderate
Database
Additive hepatotoxicity / psychotic effects
Avoid alcohol
Source: Kimi deep-research + Cla
Antidiabetic Drugs
Moderate
Database
Glycaemic disturbance
Monitor glucose; adjust antidiabetics
Source: Kimi deep-research + Cla
Isoniazid
Moderate
Database
Additive hepatotoxicity / cross-resistance via inhA
Use only if necessary; monitor LFTs
Source: Kimi deep-research + Cla
Related guidelines
Ask House about ethionamide
Continue into a citation-backed clinical answer with the drug context already attached.
Sources: KD Tripathi 7e, Goodman & Gilman 14e, Harrison 22e·Verified: 2026-05-20 · House clinical team·Cockpit curated: 2026-05-20