Toltrazuril
**Toltrazuril** is a triazinone (triazine) antiprotozoal agent primarily labeled for treating coccidiosis in poultry and swine in Europe. In companion animal medicine, it is utilized off-label as an alternative treatment for various protozoal infections. **Key Uses:** - Coccidiosis in dogs and cats - *Isospora* or *Hepatozoon* infections - Oocyst shedding stage of toxoplasmosis in cats - Overwhelming parasitic loads in reptiles (e.g., Bearded Dragons) **Clinical Pearls:** - Toltrazuril is the parent compound to **ponazuril** (toltrazuril sulfone), which is more commonly used and available in the US. - While it can induce excellent initial clinical responses in dogs with American canine hepatozoonosis (ACH), it cannot completely eliminate the parasites, and remission is usually transient. - **Regulatory Note:** It is not commercially available in the USA and must be legally imported for compassionate use.
Mecanismo: The exact mechanism of action is not completely understood, but as a triazinone derivative, it acts on all intracellular developmental stages of coccidia. - **Pathway:** It appears to inhibit protozoal enzyme systems → disrupts the division of the nucleus and the activity of the mitochondria → impairs the respiratory metabolism of the parasite → protozoal death. - It is rapidly metabolized in the liver to its active sulfone derivative, **ponazuril**.
Dosificación por especie
- Enteroepithelial cycle of toxoplasmosis (oocyst shedding) · 5-10 mg/kg PO once daily · PO · q24h · 2 days
- Coccidiosis · 30 mg/kg PO once daily · PO · q24h · 2-3 days
- Coccidiosis · 20 mg/kg PO once daily · PO · q24h · 3 days
- Isospora spp. · 9-20 mg/kg · PO · once · Single dose; further treatment is only indicated if oocyst shedding persists · Not authorized for use in cats but appears to be effective. Standard dose is 9 mg/kg. Higher doses up to 20 mg/kg can be used if required.
- Ovine coccidiosis (Eimeria ovinoidalis) · 20 mg/kg PO once · PO · once · 1 dose · Controlled study comparing efficacy against diclazuril.
- Coccidiosis in raptors · 7 mg/kg PO once daily · PO · q24h · 2-3 days
- Parasitism in Bearded Dragons · 5-15 mg/kg PO once daily · PO · q24h · 3 days
- Coccidiosis (Cystoisosporosis) prevention · 10-20 mg/kg PO one time · PO · once · 1 dose · Administer to all puppies at 3-4 weeks of age to help prevent problems associated with intestinal coccidiosis.
Vías de administración
Contraindicaciones
- Known hypersensitivity to toltrazuril or other triazinone antiprotozoals (e.g., ponazuril, diclazuril)
- Puppies or kittens < 2 weeks of age
- Animals weighing < 0.4 kg
Efectos adversos
- Generally well tolerated in birds
- Potential gastrointestinal upset in mammals
- Blisters on nose and mouth (extrapolated from ponazuril use in horses)
- Rash or hives (extrapolated from ponazuril use in horses)
- Mild diarrhoea
- Vomiting
Interacciones farmacológicas
- Emodepside · Frequently formulated together; no negative interactions known between the two, but refer to emodepside monograph for its specific interactions. · minor
Monitorización
- Clinical efficacy (resolution of clinical signs, negative fecal tests)
- Fecal flotation to monitor for resolution of oocyst shedding
- Resolution of clinical signs (e.g., diarrhea)
Sobredosis
Very limited information is available. - **Horses:** Doses up to 10X were tolerated without significant adverse effects. - **Poultry:** 5X overdoses have been tolerated without clinical signs. Decreased water intake has been observed if overdoses are greater than 5X.
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