Albendazole
Albendazole is a **broad-spectrum benzimidazole anthelmintic** used in veterinary medicine to treat a wide variety of internal parasites, including **nematodes (roundworms)**, **cestodes (tapeworms)**, **trematodes (flukes)**, and certain **protozoa (e.g., Giardia)**. * **Food Animal Use**: FDA-approved for use in cattle and sheep (suspension form) for various endoparasites. * **Small Animal Use**: Used extra-label for specific infections (e.g., *Paragonimus*, *Filaroides*, *Giardia*). However, its use in dogs and cats has significantly declined due to the risk of **bone marrow toxicity** (aplastic anemia) and hepatic dysfunction. Safer alternatives like fenbendazole are often preferred for small animals. * **Exotics**: Used extra-label in small mammals, birds, and reptiles, though toxicity has been noted in certain species (e.g., pigeons, doves, and alpaca crias).
Mechanism: Albendazole exerts its antiparasitic effects by binding selectively to parasite **ฮฒ-tubulin** โ prevents tubulin polymerization โ inhibits **microtubule formation**. * This disruption halts intracellular microtubular transport systems and cell division. * At higher concentrations, it disrupts metabolic pathways by inhibiting key enzymes like **malate dehydrogenase** and **fumarate reductase** โ impairs glucose uptake and ATP production โ leads to parasite starvation and death.
Dosing by species
- Susceptible parasites ยท 7.5 mg/kg PO (0.75 mL of the suspension per 25 lb. body weight). ยท PO ยท Single dose
- Adult liver flukes ยท 7.5 mg/kg PO; 15 mg/kg PO for adult liver flukes ยท PO ยท Single dose
- Adult liver flukes ยท 7.6 mg/kg ยท PO ยท Single dose
- Nematodes ยท 3 mL of suspension per 100 lbs of body weight PO ยท PO ยท Single dose
- Susceptible parasites ยท 7.5 mg/kg PO (0.75 mL of the suspension per 25 lb. body weight). ยท PO ยท Single dose
- Adult liver flukes ยท 7.5 mg/kg PO; 15 mg/kg PO for adult liver flukes ยท PO ยท Single dose
- Paragonimus kellicotti ยท 25 mg/kg PO q12h for 14 days ยท PO ยท q12h ยท 14 days
- Giardia ยท 25 mg/kg PO q12h for 3-5 days ยท PO ยท q12h ยท 3-5 days ยท May cause bone marrow suppression in dogs and cats.
- Liver flukes (Platynosum or Opisthorchiidae families) ยท 50 mg/kg PO once daily until ova are gone ยท PO ยท q24h ยท Until ova are gone
Routes of administration
Contraindications
- Hepatic failure
- Early pregnancy (teratogenic/embryotoxic)
- Lactating dairy cattle (of breeding age)
- Pigeons and doves (susceptible to toxicity)
- Alpaca crias (high risk of fatal neutropenia and sepsis)
Adverse effects
- Anorexia
- Lethargy and depression
- Vomiting and diarrhea
- Hepatic dysfunction
- Blood dyscrasias (aplastic anemia, neutropenia)
Drug interactions
- Cimetidine ยท Increased albendazole levels in bile and cystic fluid
- Dexamethasone ยท May increase albendazole serum levels
- Praziquantel ยท May increase albendazole serum levels
Monitoring
- Clinical efficacy (fecal exams)
- Adverse effects (especially if used in non-FDA-approved species or at high dosages)
- CBCs and liver enzymes (q4-6 weeks) if treating long-term (>1 month)
Overdose
Albendazole has a relatively wide margin of safety in ruminants, but massive overdoses are fatal. * **Cattle**: Doses of 300 mg/kg (30X recommended) have caused death. Doses of 45 mg/kg (4.5X recommended) did not cause adverse effects. * **Sheep**: Doses of 200 mg/kg (20X recommended) have caused death. * **Cats**: Receiving 100 mg/kg/day for 14-21 days showed signs of weight loss, neutropenia, and mental dullness.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.