ジアフェニルスルホン (ダプソン)
ダプソンは**スルホン系抗菌薬**および**抗炎症薬**です。獣医療では主に、特定の免疫介在性皮膚疾患（天疱瘡、皮膚血管炎など）や非定型感染症（マイコバクテリア、ニューモシスチスなど）に対する**二次選択薬または補助療法**として使用されます。 > **臨床上のポイント**: **肝毒性**や**血液疾患**などの重篤な副作用のリスクが高いため、第一選択薬として使用されることは稀です。猫はメトヘモグロビン血症や溶血性貧血に対する感受性が高いため、猫への使用は**相対的禁忌**とされています。
作用機序: **Antimicrobial action**: Acts as a competitive antagonist of **para-aminobenzoic acid (PABA)**. It inhibits the enzyme **dihydropteroate synthase (DHPS)** → blocks the synthesis of **dihydrofolic acid** → disrupts nucleic acid synthesis in susceptible organisms (similar to sulfonamides). **Anti-inflammatory action**: Dapsone exerts potent immunomodulatory effects. It inhibits the **myeloperoxidase-H2O2-halide system** → suppresses the **neutrophil respiratory burst**. It also decreases **neutrophil chemotaxis**, complement activation, antibody production, and lysosomal enzyme synthesis, making it useful for sterile, neutrophil-driven inflammatory conditions like vasculitis or Brown Recluse spider bites.
動物種別の用量
- Alternative to clofazimine for treating feline leprosy · 1 mg/kg once daily PO · PO · q24h · Caution: High risk of serious side effects. Intensive monitoring required.
- Treating mycobacteriosis · 8 mg/kg PO once daily for 6 weeks · PO · q24h · 6 weeks · Caution: High risk of serious side effects. Intensive monitoring required.
- Aural chondritis · 1 mg/kg PO q24h · PO · q24h · Caution: High risk of serious side effects. Intensive monitoring required.
- Alternative treatment for Pneumocystis carinii pneumonia · 3 mg/kg PO once daily (q24h) · PO · q24h · 56 days · From one case report of treatment of a foal.
- Alternative treatment for pemphigus · 1 mg/kg PO q8h; with sulfasalazine at 10-40 mg/kg q8h · PO · q8h
- Post-vaccination alopecia/vasculitis resistant to prednisone therapy · 1 mg/kg PO q8h · PO · q8h
- Treating mycobacteriosis · 1.1 mg/kg PO q6h until remission, then 0.3 mg/kg q8-12h after recovery · PO · q6h initially, then q8-12h · Until remission, then maintenance
- Adjunctive therapy of vasculitis · 1 mg/kg PO q8h · PO · q8h
- Adjunctive treatment of Brown Recluse spider (Loxosceles spp.) bite · 1 mg/kg PO three times daily for 10 days · PO · TID · 10 days
投与経路
禁忌
- Cats (relatively contraindicated due to high risk of neurotoxicity and hemolytic anemia)
- Hypersensitivity to dapsone or other sulfone drugs
- Patients with severe anemias or preexisting blood dyscrasias
- Preexisting hepatic dysfunction (use with extreme caution)
有害事象
- Hepatotoxicity
- Dose-dependent methemoglobinemia
- Hemolytic anemia
- Thrombocytopenia
- Neutropenias
- Gastrointestinal effects (nausea, vomiting)
- Neuropathies
- Cutaneous drug eruptions
- Photosensitivity
- Potential carcinogen
薬物相互作用
- Probenecid · May decrease the renal excretion of active metabolites of dapsone.
- Pyrimethamine · May increase risk of hematologic reactions occurring with dapsone.
- Rifampin · May decrease plasma dapsone concentrations (7-10 fold).
- Trimethoprim · May increase plasma dapsone concentrations (and vice versa) and potentially increase each other's toxicity.
モニタリング
- CBC with platelets every 2-3 weeks during first 4 months of treatment, then every 3-4 months
- Liver function tests
- Clinical signs of adverse effects (GI upset, drug eruptions, neurotoxicity, jaundice, cyanosis)
- Clinical efficacy
過量投与
Because of its toxicity potential, specific species differences in sensitivity, and pharmacokinetics, it is recommended to contact an animal poison control center in cases of dapsone overdoses. - **Clinical Signs**: In humans, overdoses generally cause nausea, vomiting, and hyperexcitability within minutes. **Methemoglobinemia** with associated depression, seizures, and cyanosis can occur. **Hemolysis** may be delayed, occurring 7-14 days after the overdose. - **Treatment**: Includes removal of drug from the gut (decontamination), **methylene blue** for methemoglobinemia, and sometimes hemodialysis to enhance removal of the drug and its monoacetyl metabolite.
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。