Drug reference

Mebendazole

Benzimidazole anthelmintic · Anti-parasitic

Also known as Mebex, Wormin, Mebendol

START

Pinworm 100 mg single dose, repeat in 2 weeks; STH 100 mg BID ×3 days or 500 mg single

TYPICAL MAX

Short-course/single-dose; high-dose systemic regimens specialist only

STOP IF

Severe skin reaction, marrow suppression (high-dose), hepatotoxicity

WATCH

Treat close contacts/hygiene (pinworm); high-dose: CBC + LFTs; avoid metronidazole co-use (SJS reports)

CDSCO approvedJan AushadhiNPPA price-controlledATC P02CA01

Dose laddermg/d

Renal dose adjustmenteGFR mL/min/1.73m²

KDIGO 2024 + manufacturer label

Pharmacokineticsplasma · t hours

ONSET: 2h · luminal action
PEAK: 2h · low systemic Cmax
t½: 4h · absorbed-fraction t½
DURATION: 1d · daily dosing (course)

EXCRETION

Mainly faecal (unabsorbed); minor renal

route + CYP

INTERACTIONS

1 major

SEVERE in our sources

PREGNANCY

Avoid first trimester; later trimesters only if clearly needed (WHO permits in deworming after 1st trimester)

FDA category + note

Top interactionssee all 5 →

MetronidazoleSevereDatabaseKimi deep-research + Cla

Available in India

28 branded formulations and 4 fixed-dose combinations. Look up specific brands in the Drugs workspace.

Jan Aushadhi — generic available at GoI pharmacies

Mechanism

Binds nematode beta-tubulin inhibiting microtubule polymerisation, blocking helminth glucose uptake → glycogen depletion and parasite death; poorly absorbed (acts in gut lumen).

Indications

Intestinal nematode infections: enterobiasis (pinworm), ascariasis, trichuriasis, hookwormMass deworming programmesCapillariasis, trichinellosis (higher doses)

Dosing

Adult: Pinworm: 100 mg single dose, repeat in 2 weeks. Ascaris/hookworm/whipworm: 100 mg BID ×3 days or 500 mg single dose.
Pediatric: ≥1–2 years same as adult (per programme); WHO uses 500 mg single dose in deworming.
Renal adjustment: No adjustment (minimal absorption).
Hepatic adjustment: Caution/monitor in high-dose prolonged use (hepatotoxicity); systemic disease use specialist.
Geriatric: No specific adjustment.
Max dose: Single-dose/short-course regimens; high-dose systemic (e.g. echinococcosis) specialist

Pharmacokinetics

Onset

Antiparasitic over days (gut)

Peak effect

Low systemic Cmax (poorly absorbed)

Duration

Course-based; single-dose for many indications

Half-life

~3–6 h (absorbed fraction)

Bioavailability

<10% (increased with fatty meal)

Protein binding

~90–95% (absorbed fraction)

Metabolism

Hepatic (extensive first-pass to inactive metabolites)

Excretion

Mainly faecal (unabsorbed); minor renal/biliary

Contraindications

Hypersensitivity to mebendazole
First trimester of pregnancy (avoid; later only if necessary)

Side effects

Common

Generally well toleratedTransient abdominal pain/diarrhoea (heavy worm burden)Nausea

Serious

Bone marrow suppression/agranulocytosis (high-dose prolonged)
Hepatotoxicity (high-dose)
Severe skin reactions (SJS/TEN — rare, often with metronidazole co-use)
Convulsions (rare, infants)

Pregnancy & lactation

Pregnancy

Avoid first trimester; later trimesters only if clearly needed (WHO permits in deworming after 1st trimester)

Lactation

Limited absorption — generally considered compatible; short course

Drug interactions

Metronidazole

Severe

Database

Reports of Stevens-Johnson syndrome / toxic epidermal necrolysis with concurrent use

Avoid concurrent metronidazole