阿托伐醌
**阿托伐醌 (Atovaquone)** 是一種高脂溶性的合成羥基萘醌類抗原蟲藥物。在獸醫學中，它為治療某些難治的蜱媒原蟲感染帶來了革命性的突破。 **主要臨床用途：** * **犬吉氏巴貝斯蟲 (Babesia gibsoni) 感染：** 與阿奇黴素 (Azithromycin) 產生協同作用。吉氏巴貝斯蟲是一種小型焦蟲，通常對傳統療法（如雙脒苯脲）具有抗藥性。阿托伐醌/阿奇黴素組合是目前的治療首選。 * **貓細胞簇蟲 (Cytauxzoon felis) 感染：** 與阿奇黴素合併使用。貓細胞簇蟲病是一種高致命性的蜱媒疾病；此藥物組合配合積極的支持性療法（靜脈輸液、肝素），已顯著提高患貓的存活率。 * **犬肺孢子蟲病 (Pneumocystosis)：** 當無法使用增效磺胺類藥物或無效時，作為肺孢子蟲肺炎的二線療法。 > **臨床要點：** 阿托伐醌單獨使用或與阿奇黴素合併使用時通常耐受性良好，但價格相當昂貴。人類複方藥物 Malarone®（阿托伐醌/氯胍）**絕對不可**替代用於犬隻，因為其中的氯胍 (proguanil) 成分會引起嚴重的胃腸道毒性。
作用機制: Atovaquone acts as a selective and potent inhibitor of the protozoan mitochondrial electron transport chain. * It acts as a structural analogue of ubiquinone (Coenzyme Q). * It binds to the ubiquinol oxidation pocket of the **cytochrome bc1 complex** (Complex III) in the protozoan inner mitochondrial membrane. * This binding blocks electron transfer → collapses the mitochondrial membrane potential → halts the function of **dihydroorotate dehydrogenase**, an enzyme critically dependent on electron transport. * Inhibition of this enzyme prevents *de novo* pyrimidine synthesis. Because these specific protozoa lack the ability to salvage preformed pyrimidines from their host, they cannot synthesize DNA or RNA, leading to parasite death.
各物種劑量
- Cytauxzoonosis (Cytauxzoon felis) · 15 mg/kg PO q8h · PO · q8h · Not specified · Give with azithromycin 10 mg/kg PO q24h. All cases were treated with IV fluids and most received heparin.
- Babesia gibsoni (Asian genotype) infections · 13.3 mg/kg PO q8h · PO · q8h · 10 days · Give with Azithromycin 10 mg/kg PO once daily. Reserve immunosuppressive therapy for cases that are not rapidly responding (3-5 days) to anti-protozoal therapy.
- Pneumocystosis · 15 mg/kg PO once daily · PO · q24h · 3 weeks · Considered second line therapy after potentiated sulfonamides.
劑量為合格獸醫專業人員的臨床參考。請務必對照最新藥品仿單及個別病患確認。
給藥途徑
禁忌症
- Patients with a known hypersensitivity to atovaquone
- Patients with severe malabsorption syndromes
- Patients who cannot tolerate oral intake or cannot take the drug with a high-fat meal
不良反應
- Gastrointestinal upset (nausea, vomiting, diarrhea)
- Rashes or hypersensitivity reactions
- Elevated liver enzymes
- CNS effects (headache, dizziness in humans)
- Fever
- Neutropenia and anemia (rare)
藥物相互作用
- Metoclopramide · Can decrease atovaquone plasma concentrations
- Tetracycline · Can decrease atovaquone plasma concentrations
- Rifampin · Can decrease atovaquone plasma concentrations
監測
- Clinical signs of efficacy (resolution of fever, lethargy, anemia)
- Serial CBCs to monitor anemia and platelet counts
- BUN, liver enzymes, and serum potassium (hypokalemia) in severe cases
- PCR testing at 60 days and 90 days post-therapy to confirm 'clearing' of B. gibsoni
過量
Limited information is available for any species regarding acute toxicity. Minimum toxic doses have not been established; laboratory animals have tolerated massive doses up to 31.5 grams without lethal effect. If an overdose occurs, treatment should be **symptomatic and supportive**. Due to high protein binding, dialysis is unlikely to be effective.
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。