Antihelminthic Drugs
Antihelminthic drugs are used to treat infections caused by helminths (parasitic worms), such as nematodes, cestodes, and trematodes.
Classification / Examples
- Mebendazole
- Thiabendazole
- Albendazole
- Praziquantel
Pharmacodynamics
- Mebendazole & Albendazole: Inhibit microtubule synthesis → block glucose uptake → ↓ ATP → worm paralysis & death
- Thiabendazole: Similar to mebendazole; disrupts microtubules → interferes with worm structure & function
- Praziquantel: Increases calcium permeability → sustained muscle contraction → detachment of worm from host tissue → immune clearance
Side Effects
- Common: Nausea, vomiting, abdominal pain, diarrhea
- Rare/Severe:
- Allergic reactions (rash, urticaria)
- Hematologic: Agranulocytosis
- Hepatotoxicity
- Neurotoxicity: Dizziness, seizures (especially with high doses)
Drug Interactions
- Mebendazole & Albendazole:
- ↑ levels with cimetidine
- ↓ efficacy with phenytoin, carbamazepine, dexamethasone
- Thiabendazole:
- ↑ theophylline levels → toxicity risk
- Praziquantel:
- ↓ levels with phenytoin, carbamazepine
- ↑ levels with cimetidine
Therapeutic Uses
- Mebendazole: Pinworms, roundworms, hookworms, whipworms
- Thiabendazole: Strongyloidiasis, cutaneous larva migrans
- Albendazole: Hydatid disease, neurocysticercosis, intestinal helminths
- Praziquantel: Schistosomiasis, liver flukes, tapeworms
Pregnancy & Milk
- Praziquantel: Safer option during pregnancy (Category B)
- Others: Contraindicated during pregnancy (especially first trimester)
- All excreted in breast milk → use with caution