ロペラミド

Loperamide

Loperamide hydrochloride

別名: Imodium A-D · Neo-Diaral · K-Pek II · Diah-Limit · Diarolaeze · Entrocalm · Norimode · PJ 185 · R 18553 · Loperamida · Loperamidum

VetSheet 獣医チームが監修更新日 2026年4月5日エビデンスに基づく獣医学リファレンス

0.08 mg/kgPO· three times daily

体重— 🐕

用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。

動物種別用量

🌎 NA — North America🌍 EU — Europe

犬

適応	用量	経路	頻度	期間	地域
Antidiarrheal	0.08 mg/kg	PO	three times daily	—	🌎 NA
Antidiarrheal	0.1-0.2 mg/kg	PO	q8-12h	—	🌎 NA
Antidiarrheal	0.1 mg/kg	PO	three times a day	Maximum 5 days	🌎 NA
Adjunctive treatment for diarrhea associated with chemotherapy	0.08 mg/kg	PO	three times daily	—	🌎 NA
Antidiarrheal	0.08 mg/kg	PO	3-4 times a day	—	🌎 NA
Antidiarrheal	0.1-0.2 mg/kg	PO	q6-12h	—	🌎 NA
Management of non-specific acute and chronic diarrhoea, and irritable bowel syndrome	0.04-0.2 mg/kg	PO	q8-12h	As needed	🌍 EU

Antidiarrheal: Collies and related breeds (MDR1 mutation) may be overly sensitive
Antidiarrheal: Potentially contraindicated when diarrhea is suspected to be caused by enteric infections
Management of non-specific acute and chronic diarrhoea, and irritable bowel syndrome: Do not use in dogs likely to be ivermectin-sensitive (e.g., collies) due to MDR1 mutation risk.

猫

適応	用量	経路	頻度	期間	地域
Diarrhea	0.04-0.06 mg/kg	PO	twice daily	—	🌎 NA
Diarrhea	0.08-0.16 mg/kg	PO	q12h	—	🌎 NA
Management of non-specific acute and chronic diarrhoea, and irritable bowel syndrome	0.04-0.2 mg/kg	PO	q8-12h	As needed	🌍 EU

Diarrhea: Using the suspension. Use is controversial; may react with excitatory behavior.
Diarrhea: Use is controversial.
Management of non-specific acute and chronic diarrhoea, and irritable bowel syndrome: Use with care; excitability may be seen.

小型哺乳類

適応	用量	経路	頻度	期間	地域
Antidiarrheal (Rabbits)	0.1 mg/kg in 1 mL of water	PO	q8h for 3 days, then once daily for 2 days	5 days total	🌎 NA
Antidiarrheal (Mice, Rats, Gerbils, Hamsters, Guinea pigs, Chinchillas)	0.1 mg/kg in 1 mL of water	PO	q8h for 3 days, then once daily for 2 days	5 days total	🌎 NA

用量は獣医専門家向けの臨床参考資料です。必ず最新の医薬品情報および個別症例に基づいて確認してください。

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概要

ロペラミドは、獣医学において主に止瀉薬および消化管（GI）運動調整薬として使用される、合成された末梢作用型のピペリジン誘導体オピオイド作動薬です。

他の多くのオピオイドとは異なり、ロペラミドは血液脳関門における P-糖タンパク質（P-gp） 排出ポンプの基質です。正常な動物では、これにより薬物が中枢神経系（CNS）に蓄積するのを防ぎ、典型的なオピオイドの神経学的副作用を最小限に抑えます。

臨床上のポイント： ロペラミドは、非感染性下痢（トセラニブなどの薬剤による化学療法誘発性下痢など）の対症療法に非常に有効です。ただし、ABCB1-1Δ（MDR1）変異 があるため、牧羊犬種（コリー、オーストラリアン・シェパードなど）への使用は極めて慎重に行うか、完全に避ける必要があります。これらの犬では、欠陥のあるP-gpポンプによりロペラミドが血液脳関門を通過し、標準用量であっても重篤で致命的な神経毒性を引き起こす可能性があります。

作用機序

Loperamide exerts its antidiarrheal effects through multiple mechanisms within the gastrointestinal tract:

μ-opioid receptor agonism: Binds to mu-receptors in the myenteric plexus of the intestinal wall → inhibits the release of acetylcholine and prostaglandins → reduces peristalsis and increases intestinal transit time, allowing for greater fluid absorption.
δ-opioid receptor agonism: Binds to delta-receptors → decreases intestinal secretion induced by cholera toxin and prostaglandins.
Calcium channel modulation: Inhibits diarrheas caused by factors utilizing calcium as a second messenger (non-cAMP/cGMP mediated).
Mucosal absorption: Directly enhances the mucosal absorption of water and electrolytes.

安全性・警告

禁忌

Dogs tested positive for the ABCB1-1Δ (MDR1) mutation
Untested dogs of herding breeds susceptible to the MDR1 mutation
Diarrhea caused by toxic ingestion (until the toxin is eliminated)
Known hypersensitivity to narcotic analgesics
Infectious enteritis (relative contraindication, as decreased motility can delay pathogen clearance)
Intestinal obstruction
Dogs likely to be ivermectin-sensitive (MDR1/ABCB1 mutation, e.g., Collies, Australian Shepherds)
Infectious enteritis (where decreased motility may delay pathogen clearance)
Toxigenic diarrhea

有害事象

Constipation
Bloat
Paralytic ileus
Toxic megacolon
Pancreatitis
CNS depression (especially in MDR1-mutant dogs)
Excitatory behavior (cats)
Excitability (especially in cats)
Profound sedation and ataxia (in MDR1 mutant dogs)

注意事項

Use with caution in patients with hypothyroidism, severe renal insufficiency, adrenocortical insufficiency (Addison's disease), and in geriatric or severely debilitated patients.

Use with extreme caution in patients with head injuries or increased intracranial pressure, as well as acute abdominal conditions (e.g., colic), as opiates may obscure the diagnosis or clinical course.

Use with extreme caution in patients suffering from respiratory disease or acute respiratory dysfunction (e.g., pulmonary edema secondary to smoke inhalation).

Use with extreme caution in patients with hepatic disease exhibiting CNS clinical signs of hepatic encephalopathy, as hepatic coma may result.

Small Patient Dosing: Many clinicians recommend avoiding tablet/capsule forms in dogs weighing less than 10 kg due to potency; dosage titration using liquid forms is recommended for safe use.