羅硝唑
**羅硝唑 (Ronidazole)** 是一種強效的 **5-硝基咪唑類 (5-nitroimidazole)** 抗生素與抗原蟲藥物。雖然在結構上與甲硝唑 (metronidazole) 相似，但它對某些具抗藥性的原蟲展現出更佳的療效。 * 主要在獸醫學中以仿單標示外使用 (off-label use) 的方式，用於根除貓的 **胎兒三毛滴蟲 (*Tritrichomonas foetus*)** 感染，這是造成貓咪慢性大腸性腹瀉的常見原因。 * 也可用於鳥類醫學，治療非食用鳥類（如鴿子、雀鳥）的毛滴蟲感染。 **臨床要點**：由於其味道極度苦澀且對人類有潛在健康風險（疑似致癌物），必須謹慎地配製成完整的明膠膠囊。嚴禁使用於經濟動物（食用動物）。
作用機制: Ronidazole is a prodrug that requires activation by protozoal organelles called **hydrogenosomes**. * Inside the hydrogenosome, the drug is reduced → forms **polar autotoxic anion radicals**. * These highly reactive radicals bind to and disrupt protozoal DNA → inhibition of nucleic acid synthesis → **cell death**. *Note*: While it shares this mechanism with metronidazole, ronidazole often retains activity against metronidazole-resistant _T. foetus_ strains, though resistance to ronidazole has been documented.
各物種劑量
- treatment of T. foetus infections · 30 mg/kg PO q24h · PO · q24h · 14 days · Likely to be most effective in resolving diarrhea and eradicating T. foetus infection. Must be given in capsule form due to bitter taste.
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
給藥途徑
禁忌症
- Hypersensitivity to ronidazole or other 5-nitroimidazoles (e.g., metronidazole)
- Food-producing animals (FDA prohibited)
- Pregnant or nursing cats (safety not established; use with extreme caution)
不良反應
- Neurotoxicity (lethargy, anorexia, ataxia, nystagmus, seizures, behavior changes)
- Gastrointestinal effects (anorexia, vomiting)
- Carcinogenic potential (tumors in mice and rats)
- Testicular toxicity (reported in dogs)
藥物相互作用
- Alcohol · May induce a disulfiram-like reaction (nausea, vomiting, cramps)
- Cimetidine · May decrease the metabolism of ronidazole and increase the likelihood of dose-related side effects
- Ketoconazole · May decrease the metabolism of ronidazole and increase the likelihood of dose-related side effects
- Cyclosporine · Ronidazole may increase the serum levels of cyclosporine
- Tacrolimus · Ronidazole may increase the serum levels of tacrolimus
- Fluorouracil · Ronidazole may increase the serum levels of fluorouracil and increase risk for toxicity
- Lithium · Ronidazole may increase lithium serum levels and increase risk for lithium toxicity
- Oxytetracycline · Reportedly may antagonize the therapeutic effects of metronidazole (and presumably ronidazole)
- Phenobarbital · May increase the metabolism of ronidazole thereby decreasing blood levels
- Rifampin · May increase the metabolism of ronidazole thereby decreasing blood levels
- Phenytoin · May increase the metabolism of ronidazole thereby decreasing blood levels
- Warfarin · May prolong INR/PT; avoid concurrent use if possible or intensify monitoring
監測
- Clinical efficacy (diarrhea improvement)
- Adverse effects (neurotoxicity, vomiting, anorexia)
- PCR testing (to confirm infection; note that negative results after treatment do not conclusively prove eradication)
過量
Overdoses can cause severe **neurotoxicity**, hemorrhage, and death (as reported in society finches consuming ronidazole in drinking water). Cats receiving 50 mg/kg twice daily have a greater incidence of neurotoxicity. **Treatment**: * Discontinue further therapy immediately. * Treat supportively. * Consider administering a GABA inhibitor, such as **diazepam**, to competitively inhibit GABA receptors in the CNS and control neurological signs.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。