セラメクチン
セラメクチンは、獣医療で広く使用されている広域スペクトルの半合成アベルメクチン系局所抗寄生虫薬です。 **主な臨床的特徴:** * **広域スペクトル:** 犬糸状虫（フィラリア）の幼虫、ノミ、ミミヒゼンダニ、センコウヒゼンダニ、および一部のマダニなど、幅広い国内外の寄生虫に有効です。 * **猫の腸内寄生虫:** 猫では、鉤虫や回虫にも有効です。 * **高い安全性:** アベルメクチンに敏感な犬種（MDR1変異を持つコリーなど）であっても、推奨される局所ラベル用量で使用すれば非常に安全です。 * **全身吸収:** 皮膚の脂質層に留まる多くの局所用ノミ・マダニ駆除薬とは異なり、セラメクチンは全身に吸収されます。これはフィラリアや体内寄生虫に対する有効性に不可欠です。
作用機序: Selamectin acts by binding to **glutamate-gated chloride channels** in the nervous system of invertebrates. Binding → increased permeability of the cell membrane to chloride ions → hyperpolarization of the nerve or muscle cell → **flaccid paralysis and death** of the parasite. *Clinical Pearl:* Mammals generally lack glutamate-gated chloride channels, and macrocyclic lactones do not readily cross the intact mammalian blood-brain barrier (mediated by P-glycoprotein), conferring a high margin of safety.
動物種別の用量
- Heartworm prevention, flea control, ear mites, hookworms, roundworms · 6 mg/kg · topical · monthly (ear mites, hookworms, roundworms = once, repeat in one month if necessary)
- Notoedric (face/head) mange (Notoedres cati) · 6 mg/kg · topical · once
- Biting lice · 6 mg/kg · topical · once
- Flea treatment/prevention, heartworm prevention, ear mites, biting lice, roundworms, hookworms · 6 mg/kg · topical · monthly · Ongoing for prevention · Apply to the skin at the base of the neck in front of the shoulder blades.
- Heartworm prevention · 18 mg/kg · topical · every 30 days
- Flea treatment/prevention, heartworm prevention (Off-label / specific regional labels) · 15 - 18 mg/kg · topical · monthly · Ongoing for prevention · Use the kitten/small cat pipette.
- Ear mites (P. cunuculi) in rabbits · 6-18 mg/kg · topical · once
- Mites and fleas (Off-label) · 6 - 18 mg/kg · topical · monthly · As needed · Off-label use. Dose varies by species (e.g., rabbits, guinea pigs).
投与経路
禁忌
- Application to broken skin
- Application to wet hair coats
- Use in severely debilitated or underweight animals (relative)
- Puppies and kittens under 6 weeks of age
- Sick, debilitated, or severely underweight animals
- Known hypersensitivity to the active substance or excipients
有害事象
- Transient localized alopecia at application site (rare)
- Mild, transient gastrointestinal signs (vomiting, diarrhea) if ingested
- Transient local alopecia at the application site
- Application site irritation or pruritus
- Rarely: vomiting, diarrhea, lethargy, or anorexia
- Rarely: neurological signs (tremors, ataxia) in highly sensitive individuals
薬物相互作用
- Other macrocyclic lactones (e.g., ivermectin, milbemycin) · Potential for additive toxicity, though selamectin has a high margin of safety. · minor
- P-glycoprotein inhibitors (e.g., ketoconazole, cyclosporine) · May theoretically increase systemic absorption and CNS penetration, increasing the risk of toxicity. · moderate
モニタリング
- Clinical efficacy
- Owner compliance with treatment regimen
- Efficacy of parasite control
- Application site for signs of irritation or alopecia
過量投与
Generally very safe. Overdoses up to 10 times the recommended dose typically do not produce clinical signs in dogs or cats. If massive accidental ingestion occurs, monitor for neurologic signs (ataxia, tremors, mydriasis) and provide supportive care.
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。