クロファジミン
クロファジミンは、脂溶性が極めて高いフェナジン系色素の抗抗酸菌性抗生物質です。獣医学においては、主に猫ハンセン病や犬ハンセン病様肉芽腫などのハンセン病様症候群、および*マイコバクテリウム・アビウム*コンプレックス（MAC）感染症の治療において、多剤併用療法の一部として使用されます。 **臨床上のポイント:** * **併用療法:** 抗酸菌は根絶が非常に困難であり、耐性を獲得しやすいため、クロファジミンが単独療法として使用されることはほとんどありません。 * **脂溶性:** 極めて高い脂溶性を持つため、脂肪組織や網内系（マクロファージ）に大量に蓄積します。 * **着色作用:** この薬は色素としての性質を持つため、皮膚、眼、体液の顕著で長期的な変色という特徴的な副作用を引き起こします。 * **入手の難しさ:** 獣医師が小動物用に正確な用量を入手・調剤することは非常に困難な場合があり、多くの場合、調剤薬局の支援が必要となります。
作用機序: Clofazimine exerts a slowly bactericidal effect against susceptible mycobacteria (*M. leprae*, *M. tuberculosis*, *M. avium* complex, *M. bovis*, *M. chelonei*). * **DNA Binding:** It binds directly to mycobacterial DNA (preferentially at guanine base sequences) → blocks template function → **inhibits DNA replication and cell growth**. * **Intracellular Accumulation:** It is heavily taken up by macrophages, concentrating the drug exactly where intracellular mycobacteria reside. * **Immunomodulation:** Exhibits anti-inflammatory and immunosuppressive properties, likely by inhibiting T-lymphocyte activation and proliferation, though the exact mechanism remains poorly understood.
動物種別の用量
- Avian mycobacteriosis · 6 mg/kg PO once daily · PO · q24h · Protocol 1: with rifampin 45 mg/kg and ethambutol 30 mg/kg.
- Avian mycobacteriosis (recommended regime for raptors) · 1.5 mg/kg PO q24h · PO · q24h · Protocol 2: with ethambutol 20 mg/kg, cycloserine 5 mg/kg, enrofloxacin 15 mg/kg q12h.
- Mycobacterium avium complex (MAC) as part of a multi-drug regimen · 4 mg/kg PO once daily · PO · q24h · Other drugs that may be used in combination include doxycycline, clarithromycin, and/or enrofloxacin.
- M. avium intracellularae complex infections, leprosy, or opportunistic mycobacteriosis · 4-8 mg/kg PO once a day · PO · q24h · 4 weeks · Usually as part of a multi-drug protocol.
- Mycobacterial infections · 4-8 mg/kg · PO · q24h · 2-6 months · Generally used in combination therapy with other antimicrobials including fluoroquinolones and clarithromycin.
- Treatment of feline leprosy · 25-50 mg once per day or 50 mg every other day · PO · q24h or q48h · Using a regimen of either two or three drugs (with clarithromycin and/or rifampin).
- Treatment of localized atypical mycobacterial infections · 8 mg/kg PO once daily · PO · q24h · At least 4 weeks beyond complete clinical resolution · Perform wide surgical excision of lesion if possible. Base antibiotic selection on culture and susceptibility results.
投与経路
禁忌
- Use with caution in patients with pre-existing gastrointestinal conditions (diarrhea, abdominal pain)
- Known hypersensitivity to clofazimine
有害事象
- Skin, eye, and body fluid discoloration (pink to brownish-black)
- Gastrointestinal pain, nausea, vomiting, diarrhea (dose-limiting)
- Hepatotoxicity (reported in a dog receiving concurrent rifampin)
- Photosensitization (reported in a cat)
- Nausea
- Diarrhoea
- Discoloration of skin, eyes, and body fluids (red-brown/orange)
- Renal impairment
- Hepatic impairment
- Photosensitization
薬物相互作用
- Isoniazid · May reduce clofazimine levels in the skin and increase amounts in plasma and urine; clinical significance is unclear.
- Dapsone · May reduce the anti-inflammatory effects of clofazimine; clinical significance is unclear.
モニタリング
- Efficacy against mycobacterial disease
- Adverse effects (primarily gastrointestinal)
- Hepatic function (especially in dogs)
- Hepatic function (ALT, AST, ALP, Bilirubin)
- Renal function (BUN, Creatinine, SDMA)
- Clinical signs of photosensitization
- Gastrointestinal tolerance
過量投与
Very limited data is available. The LD50 for rabbits is 3.3 g/kg and is greater than 5 g/kg in mice, rats, and guinea pigs. Treatment, if required, would include gut emptying and supportive care. Contact an animal poison control center for additional guidance.
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。