Oxibendazole
Oxibendazole is a **benzimidazole anthelmintic** primarily utilized in equine medicine for the eradication of various internal nematodes. * **Key Targets**: Large roundworms (*Parascaris equorum*), large strongyles (*Strongylus edentatus, S. equinus, S. vulgaris*), small strongyles, threadworms, and pinworms (*Oxyuris equi*). * **Clinical Pearl**: Benzimidazole resistance is a widespread and growing concern in equine parasitology, particularly among small strongyles (cyathostomins) and *Parascaris equorum*. Routine **Fecal Egg Count Reduction Testing (FECRT)** is highly recommended to monitor farm-specific efficacy. A reduction value of less than 90% in 5-10 horses suggests resistance on a given farm. * While primarily labeled for horses, it has historical and off-label applications in cattle, sheep, and swine.
Mecanismo: Benzimidazoles exert their anthelmintic effect by selectively binding to nematode **β-tubulin**. * **Primary Mechanism**: Binds to tubulin → prevents tubulin polymerization → inhibits **microtubule formation**. This disrupts essential intracellular transport systems within the parasite. * **Secondary Mechanism**: At higher concentrations, it disrupts metabolic pathways by inhibiting key enzymes such as **fumarate reductase** and **malate dehydrogenase**, ultimately starving the parasite of energy (ATP depletion). * *Pharmacological Note*: The selective toxicity arises because benzimidazoles have a much higher affinity for nematode tubulin compared to mammalian tubulin.
Dosificación por especie
- Susceptible parasites · 10-20 mg/kg PO · PO · Once
- Susceptible parasites · 10-20 mg/kg PO · PO · Once
- Susceptible parasites · 10 mg/kg PO; 15 mg/kg PO for strongyloides · PO · Once · Retreat in 6-8 weeks if reinfection is likely · Horses maintained on premises where reinfection is likely to occur should be retreated in 6-8 weeks.
- Susceptible parasites · 15 mg/kg, PO · PO · Once
Las dosis son una referencia clínica para veterinarios colegiados. Confirme siempre con la ficha técnica vigente y el paciente individual.
Vías de administración
Contraindicaciones
- Severely debilitated horses
- Horses suffering from colic
- Toxemia
- Infectious disease
Efectos adversos
- Hypersensitivity reactions (secondary to antigen release by dying parasites)
- Periportal hepatitis (historically noted in dogs when combined with diethylcarbamazine)
Monitorización
- Efficacy (via Fecal Egg Count Reduction Test - FECRT)
Sobredosis
Doses of 60 times those recommended elicited no adverse reactions in horses tested. It is unlikely that this compound would cause serious toxicity when given alone to horses.
La referencia de fármacos de VetSheet está destinada a veterinarios colegiados como apoyo a la decisión clínica, no sustituye el juicio profesional ni la ficha técnica vigente del fabricante.