ピランテルパモ酸塩
ピランテルパモ酸塩は、広く使用されている非常に安全な**ピリミジン系駆虫薬**であり、主に様々な動物種の消化管内線虫（回虫や鉤虫など）に対して有効です。 パモ酸塩は消化管からの吸収が悪いため、標的寄生虫が生息する腸管腔内で高濃度に達します。安全域が非常に広く、嗜好性の高い経口懸濁液が利用できるため、小児獣医療（子犬や子猫の定期駆虫）において不可欠な薬剤です。 > **臨床のポイント:** 回虫や鉤虫には非常に有効ですが、標準用量のピランテルは鞭虫（*Trichuris* spp.）やほとんどの条虫には無効です。ただし馬においては、回盲部条虫（*Anoplocephala perfoliata*）の駆除に倍量投与が用いられます。馬の円虫や犬の鉤虫（*Ancylostoma caninum*）における耐性の発現は、臨床上の新たな懸念事項となっています。
作用機序: Pyrantel acts as a **depolarizing neuromuscular blocking agent** in susceptible parasites. * It binds selectively to **nicotinic acetylcholine receptors** on the somatic muscle cells of the nematode. * This binding causes continuous depolarization and an influx of calcium → **spastic paralysis** of the worm. * Paralyzed worms lose their ability to maintain attachment to the host's intestinal mucosa and are subsequently expelled alive in the feces via normal gastrointestinal peristalsis. * It also possesses mild **cholinesterase inhibitory** properties, further contributing to the accumulation of acetylcholine at the parasite's neuromuscular junction.
動物種別の用量
- For susceptible parasites · Pyrantel tartrate: 25 mg/kg, PO · PO · Single dose
- For susceptible parasites · Pyrantel tartrate: 25 mg/kg, PO · PO · Single dose
- For susceptible parasites using combination product with praziquantel (Drontal) · Administer a minimum dose of 2.27 mg praziquantel and 9.2 mg pyrantel pamoate per pound of body weight according to the dosing tables on labeling. · PO · Single dose · May be given directly by mouth or in a small amount of food. Do not withhold food prior to or after treatment. If reinfection occurs, treatment may be repeated.
- Ascarids, Hookworms, Physaloptera · 5 mg/kg, PO; repeat in 2 weeks (one time only for Physaloptera) · PO · repeat in 2 weeks
- For susceptible parasites · 10 mg/kg PO, repeat in 3 weeks · PO · repeat in 3 weeks
- Kittens · 5-10 mg/kg PO; can be repeated every 2-3 weeks until at least 12 weeks of age. · PO · every 2-3 weeks · until at least 12 weeks of age · Can be treated as early as 2-3 weeks of age
- For susceptible parasites · Pyrantel tartrate: 25 mg/kg, PO · PO · Single dose
投与経路
禁忌
- Severely debilitated animals
有害事象
- Emesis (rare, primarily in small animals)
薬物相互作用
- Diethylcarbamazine · Increased risk for adverse effects
- Levamisole · Because of similar mechanisms of action (and toxicity), do not use concurrently
- Morantel · Because of similar mechanisms of action (and toxicity), do not use concurrently
- Organophosphates · Increased risk for adverse effects
- Piperazine · Pyrantel and piperazine have antagonistic mechanisms of action; do not use together
モニタリング
- Fecal egg count reduction testing (FECRT) for strongyle nematodes (especially in horses to monitor for resistance)
- Resolution of clinical signs of parasitism
- Routine fecal flotations 2-4 weeks post-treatment
過量投与
Pyrantel has a moderate to wide margin of safety. * Dosages up to approximately **7 times** the recommended dose generally result in no toxic reactions. * In horses, doses of **20X** yielded no adverse effects. * The LD50 in mice and rats for pyrantel tartrate is 170 mg/kg; >690 mg/kg for pyrantel pamoate in dogs. * **Chronic dosing** of pyrantel pamoate in dogs resulted in clinical signs when given at 50 mg/kg/day, but not at 20 mg/kg/day over 3 months. * **Clinical signs of toxicity** may include increased respiratory rates, profuse sweating (in species with sweat glands), ataxia, or other cholinergic effects.
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。