アンプロリウム
アンプロリウムは広く使用されている**抗コクシジウム薬**であり、構造的にチアミン（ビタミンB1）の類似体です。FDAでは主に家禽や牛のアイメリア（*Eimeria*）感染症の治療および予防として承認されていますが、伴侶動物、小型哺乳類、エキゾチックアニマルのコクシジウム症（犬猫のシストイソスポラ *Cystoisospora* spp.など）の治療に適用外使用されることがよくあります。 **臨床のポイント:** * チアミンの競合的阻害剤として作用するため、短期間の投与では一般的に安全域が広いですが、長期使用によりチアミン欠乏症（反芻動物の白質脳軟化症や小動物の神経症状）を引き起こす可能性があります。 * 治療期間は通常12〜14日を超えないようにすべきです。 * 液体製剤は非常に苦味が強いため、飲料水に混ぜて投与する場合は、十分な水分補給ができているか患者を注意深く監視する必要があります。
作用機序: Amprolium is a **thiamine (Vitamin B1) analog**. It competitively inhibits the active transport and utilization of thiamine by the parasite. * **Mechanism:** Amprolium → blocks thiamine uptake → disrupts carbohydrate metabolism in the parasite (specifically inhibiting **thiamine pyrophosphate (TPP)**-dependent enzymes) → parasite death. * It primarily targets the **first-generation schizont** in the cells of the intestinal wall, preventing differentiation into merozoites. It may also suppress the sexual stages and sporulation of oocysts. * Because the host's thiamine transport mechanisms have a lower affinity for amprolium than the parasite's, toxicity to the host is minimized during short-term therapy.
動物種別の用量
- Coccidiosis (Lambs) · 55 mg/kg daily · PO · q24h · 19 days
- Eimeria macusaniensis (Camelids - New World) · 10 mg/kg · PO · q24h · 5 days · Dosed for camelids
- Eimeria macusaniensis (Camelids - New World) · 10 mg/kg as a 1.5% solution · PO · q24h · 10-15 days · Give thiamine at 10 mg/kg SC once daily every 5 days during treatment. Dosed for camelids.
- Coccidiosis (Small Pups < 10 kg adult weight) · 100 mg (total dose) · PO · q24h · 7-12 days · Using the 20% powder in a gelatin capsule
- Coccidiosis (Large Pups > 10 kg adult weight) · 200 mg (total dose) · PO · q24h · 7-12 days · Using the 20% powder in a gelatin capsule
- Coccidiosis (Pups or bitches, in food) · 250-300 mg total dose · PO · q24h · 7-12 days · Using the 20% powder on food
- Coccidiosis (Pups or bitches, in water) · 30 mL of the 9.6% solution in one gallon of water · PO · ad libitum · 7-10 days · No other water provided
- Prophylaxis · 0.075% solution as drinking water · PO · ad libitum
- Coccidiosis (Combination therapy) · 150 mg/kg of amprolium and 25 mg/kg of sulfadimethoxine · PO · q24h · 14 days
- Control of coccidiosis · 1.5 tablespoonsful (22.5 mL) of the 9.6% solution per one gallon of water · PO · ad libitum · Not to exceed 10 days · Sole drinking water source. Monitor water consumption; rarely some dogs may not drink due to bitter taste.
投与経路
禁忌
- Prolonged use (>12-14 days) especially in puppies
- Concurrent high-dose thiamine supplementation (reduces efficacy)
有害事象
- Neurologic disturbances (rare, dose-related)
- Depression
- Anorexia
- Diarrhea
- Thiamine deficiency (polioencephalomalacia) with prolonged high doses
薬物相互作用
- Thiamine · Exogenously administered thiamine in high doses may reverse or reduce the anticoccidial efficacy of amprolium.
- Thiamine (Vitamin B1) · Exogenously administered thiamine may reduce the efficacy of amprolium. · major
モニタリング
- Clinical efficacy (resolution of diarrhea, negative fecal floats)
- Hydration status (especially if administered in drinking water)
- Neurologic signs (ataxia, depression) indicating potential thiamine deficiency
過量投与
Amprolium has induced **polioencephalomalacia (PEM)** in sheep when administered at 880 mg/kg PO for 4-6 weeks and at 1 gram/kg for 3-5 weeks. Erythrocyte production also ceased in lambs receiving these high dosages. In dogs, overdoses of amprolium will produce neurologic clinical signs. **Treatment:** * Discontinue amprolium therapy immediately. * Administer parenteral thiamine (1-10 mg/day IM or IV).
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。