呋喃唑酮
呋喃唑酮（Furazolidone）是一種合成的**硝基呋喃類（nitrofuran）**抗菌與抗原蟲藥物。在獸醫學歷史上，它曾被作為小動物腸道感染的二線治療藥物，特別是針對**梨形鞭毛蟲（Giardia）**、**球蟲（Coccidia）**以及多種腸道致病菌（如彎曲桿菌、沙門氏菌、大腸桿菌）。 > **臨床要點：** 由於許多國家已將人類商業製劑下架，且美國 FDA 嚴格禁止在經濟動物（食用動物）中標示外使用（因硝基呋喃類具有潛在致癌性），目前在現代獸醫臨床上的使用已極為罕見。對於梨形鞭毛蟲等腸道感染，目前多優先選擇更安全且易取得的替代藥物，如芬苯達唑（fenbendazole）與甲硝唑（metronidazole）。
作用機制: 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).
各物種劑量
- 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
給藥途徑
禁忌症
- Known hypersensitivity to furazolidone or other nitrofurans
- Food-producing animals (FDA strictly prohibits extralabel use)
- Pregnant queens (per some references)
不良反應
- Anorexia
- Vomiting
- Abdominal cramping
- Diarrhea
- Urine discoloration (dark yellow to brown)
藥物相互作用
- 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.
監測
- Efficacy (stool exams for parasitic infections)
過量
Moderate overdoses are unlikely to cause significant toxicity. Gut emptying may be considered for large overdoses.
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