Mebendazole

# Mebendazole ## Overview - **Classification**: Anthelmintic, Benzimidazole derivative - **Mechanism**: Selectively inhibits microtubule synthesis in parasitic worms, leading to impaired glucose uptake and depletion of glycogen stores, ultimately resulting in the worm's death. ## Primary Indications 1. **Enterobiasis (Pinworm)** - Common intestinal infection 2. **Ascariasis (Roundworm)** - Common large intestinal nematode 3. **Hookworm infections** (Ancylostomiasis, Necatoriasis) - Intestinal blood-feeding nematodes 4. **Trichuriasis (Whipworm)** - Intestinal nematode, often causes rectal prolapse ## Adult Dosing ### Standard Dosing **Enterobiasis (Pinworm)** - **Dose**: **100 mg** - **Frequency**: Single dose - **Route**: Oral (chewable tablet) - **Duration**: Single treatment. May repeat in 2-3 weeks if re-infection occurs or symptoms persist. **Ascariasis, Hookworm, Trichuriasis** - **Dose**: **100 mg** - **Frequency**: Twice daily - **Route**: Oral (chewable tablet) - **Duration**: 3 consecutive days ### Dose Adjustments - **Renal Impairment**: No specific dose adjustment necessary. - **Hepatic Impairment**: Caution advised; limited data. Monitor for adverse effects. - **Elderly Patients**: No specific dose adjustment necessary; use adult dosing. ## Pediatric Dosing ### Neonates (0-28 days) - **Dose**: Generally **not recommended** - **Special Notes**: Limited safety and efficacy data. Potential for seizures in very young children has been reported. Use only if clear benefit outweighs risks and under specialist supervision. ### Infants (1-12 months) - **Dose**: Generally **not recommended** - **Special Notes**: Limited safety and efficacy data. Use only if clear benefit outweighs risks, e.g., severe or disseminated infection, and under specialist supervision. Dosing, if used, may be **100 mg** orally twice daily for 3 days for ascariasis, hookworm, trichuriasis, or **100 mg** single dose for enterobiasis (off-label). ### Children (1-12 years) **Enterobiasis (Pinworm)** - **Dose**: **100 mg** - **Frequency**: Single dose - **Route**: Oral (chewable tablet) - **Maximum**: **100 mg** per dose - **Special Notes**: Repeat in 2-3 weeks if re-infection or symptoms persist. **Ascariasis, Hookworm, Trichuriasis** - **Dose**: **100 mg** - **Frequency**: Twice daily - **Route**: Oral (chewable tablet) - **Duration**: 3 consecutive days - **Maximum**: **200 mg** per day for 3 days ### Adolescents (13-18 years) - **Dose**: Use adult dosing as above. - **Maximum**: Adult dose limits apply. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to mebendazole or any component. - **Absolute**: Co-administration with metronidazole (risk of Stevens-Johnson syndrome/toxic epidermal necrolysis). - **Relative**: Children under **1 year** (due to limited data and seizure risk, see pediatric notes). ### Common Adverse Effects - **Very Common (>10%)**: None specifically listed. - **Common (1-10%)**: Abdominal pain, diarrhea, flatulence, nausea, vomiting (especially with heavy worm burden). - **Serious but Rare**: Agranulocytosis, neutropenia (with prolonged high-dose use), hepatitis, Stevens-Johnson syndrome, toxic epidermal necrolysis, seizures (rare, especially in very young). ### Key Drug Interactions - **Metronidazole**: Concurrent use **contraindicated** due to increased risk of serious skin reactions (SJS/TEN). - **Phenytoin/Carbamazepine**: May **decrease** mebendazole plasma concentrations, reducing efficacy. - **Cimetidine**: May **increase** mebendazole plasma concentrations, potentially increasing adverse effects. ## Monitoring & Follow-up - **Before Treatment**: Stool examination for ova and parasites (O&P) to confirm diagnosis (except for pinworm, where tape test is common). - **During Treatment**: Clinical response. For prolonged/high-dose use (e.g., for hydatid disease), monitor LFTs and CBC (neutropenia). - **Clinical Signs**: Watch for resolution of symptoms. For pinworm, repeat tape test 1-2 weeks after treatment. If symptoms persist, consider re-treatment or alternative diagnosis. ## Clinical Pearls - 💡 **Chewable Tablet**: Mebendazole tablets are chewable and can be crushed or mixed with food, which may help with administration, especially in children. - 💡 **Household Treatment**: For pinworm, treating the entire household simultaneously is often recommended to prevent re-infection. - 💡 **Hygiene Importance**: Emphasize strict personal hygiene (handwashing, nail care) during and after treatment to prevent re-infection. - 💡 **No Dietary Restrictions**: Mebendazole can be taken with or without food; no special dietary considerations are needed. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.