フラゾリドン
フラゾリドン（Furazolidone）は、合成**ニトロフラン系**の抗菌および抗原虫薬です。歴史的に、小動物の腸管感染症、特に**ジアルジア**、**コクシジウム**、およびさまざまな腸管病原菌（カンピロバクター、サルモネラ、大腸菌など）に対する二次選択薬として使用されてきました。 > **臨床のポイント:** 多くの国で人間用の市販薬が市場から撤退しており、またFDAが食用動物への適応外使用を厳しく禁止している（ニトロフラン系の発がん性の懸念による）ため、現代の獣医療での使用は極めてまれです。ジアルジア症などの腸管感染症には、フェンベンダゾールやメトロニダゾールなどのより安全で入手しやすい代替薬が現在標準治療として推奨されています。
作用機序: Furazolidone acts as a prodrug. Inside susceptible organisms, it is reduced by **bacterial flavoproteins** (nitroreductases) → highly reactive intermediate compounds are formed → these intermediates cause severe oxidative damage to **ribosomal proteins, DNA, and RNA**, disrupting cellular metabolism and inhibiting protein synthesis. * **Antiprotozoal mechanism:** While not fully elucidated, it likely involves similar oxidative damage to essential protozoal enzymes. * **MAO Inhibition:** Furazolidone also acts as a **monoamine oxidase inhibitor (MAOI)** in the mammalian host, which can lead to significant drug and dietary interactions (e.g., with tyramine-rich foods or sympathomimetic drugs).
動物種別の用量
- Giardia · 4 mg/kg PO twice daily (q12h) · PO · q12h · 7-10 days · If re-treatment is required, elevated dosages or lengthened treatment regimens may provide better results.
- Giardia · 4 mg/kg, PO twice daily (q12h) · PO · q12h · 7 days
- Cystoisospora spp. · 8-20 mg/kg PO q12-24h · PO · q12-24h · 5 days
- Coccidiosis · 8-20 mg/kg PO once daily · PO · q24h · 7 days
- Giardiasis · 4 mg/kg PO q12h · PO · q12h · 5-10 days
- Amebiasis · 2.2 mg/kg PO q8h · PO · q8h · 7 days
- Amebic colitis · 2.2 mg/kg PO q8h · PO · q8h · 7 days
- Coccidiosis · 8-20 mg/kg PO for one week · PO · Unknown · 1 week
- Giardia · 4 mg/kg PO q12h · PO · q12h · 5 days
- Susceptible infections · 4 mg/kg PO three times daily · PO · q8h
- Amebic colitis · 2.2 mg/kg PO q8h · PO · q8h · 7 days
投与経路
禁忌
- Known hypersensitivity to furazolidone or other nitrofurans
- Food-producing animals (FDA strictly prohibits extralabel use)
- Pregnant queens (per some references)
有害事象
- Anorexia
- Vomiting
- Abdominal cramping
- Diarrhea
- Urine discoloration (dark yellow to brown)
薬物相互作用
- Alcohol · May cause a disulfiram-like reaction.
- Amitraz · Concurrent use not recommended due to MAO inhibition; dangerous hypertension could occur.
- Buspirone · Concurrent use not recommended due to MAO inhibition; dangerous hypertension could occur.
- Selegiline · Concurrent use not recommended due to MAO inhibition; dangerous hypertension could occur.
- Sympathomimetic amines (phenylpropanolamine, ephedrine, etc.) · Concurrent use not recommended due to MAO inhibition; dangerous hypertension could occur.
- Tricyclic antidepressants · Concurrent use not recommended due to MAO inhibition; dangerous hypertension could occur.
- High tyramine foods (fish, poultry) · Concurrent use not recommended due to MAO inhibition; dangerous hypertension could occur.
モニタリング
- Efficacy (stool exams for parasitic infections)
過量投与
Moderate overdoses are unlikely to cause significant toxicity. Gut emptying may be considered for large overdoses.
VetSheet の薬剤リファレンスは、獣医療従事者向けの臨床意思決定支援を目的としており、専門的判断やメーカーの最新添付文書に代わるものではありません。