乙胺嘧啶與磺胺嘧啶

用途

• Treatment of EPM
• Maintaining clinical remission (for horses that have had two relapses)

給藥方式

可能的副作用

• Bone marrow suppression (anemia, leukopenia, neutropenia, thrombocytopenia)
• Reduced appetite or anorexia
• Loose stools or diarrhea
• Urticaria (hives)
• Treatment crisis (temporary worsening of neurologic signs due to parasite die-off)
• CNS effects (seizures, depression - though often secondary to the underlying EPM)

注意事項與禁忌

• Hypersensitivity to pyrimethamine or sulfadiazine
• Horses intended for human consumption
• Use with extreme caution in horses with **preexisting hematologic abnormalities** or those receiving other bone marrow-suppressing drugs. **Pregnancy/Nursing:** Pyrimethamine is teratogenic in rats, and fetal abnormalities have been seen in foals. Sulfas cross the placenta and are distributed into milk. Use in pregnant animals only when benefits clearly outweigh risks. Consider using milk replacer for nursing offspring. **Treatment Crisis:** Neurologic signs may worsen during the first few days to 5 weeks of treatment due to an inflammatory reaction secondary to dying parasites in the CNS.

藥物相互作用

• Antacids: May decrease the bioavailability of sulfonamides if administered concurrently.
• Highly protein-bound drugs (e.g., methotrexate, phenylbutazone, thiazide diuretics, salicylates, probenecid, phenytoin, warfarin): Sulfonamides may displace other highly bound drugs, potentially increasing their free (active) plasma concentrations and risk of toxicity.
• p-Aminobenzoic acid (PABA): Reportedly antagonistic towards the activity of pyrimethamine; clinical significance is unclear.
• Trimethoprim: Use with pyrimethamine/sulfa is not recommended in humans as adverse effects may be additive; however, this combination has been used clinically in horses.

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