カプトプリル
Captopril
1-[(2S)-3-mercapto-2-methylpropionyl]-L-proline (SQ-14225)
別名: Capoten · Capozide · captoprilum · SQ-14225
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
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 |
|---|---|---|---|---|---|
| CHF / Hypertension | 0.5-2 mg/kg PO three times daily | PO | TID | — | 🌎 NA |
| CHF / Hypertension | 0.5-2 mg/kg PO q8-12h | PO | q8-12h | — | 🌎 NA |
猫
| 適応 | 用量 | 経路 | 頻度 | 期間 | 地域 |
|---|---|---|---|---|---|
| CHF / Hypertension | 1/4 to 1/2 of a 12.5 mg tablet PO q8-12h | PO | q8-12h | — | 🌎 NA |
| Dilative, restrictive or hypertrophic cardiomyopathy | 0.55-1.54 mg/kg PO q8-12h | PO | q8-12h | — | 🌎 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。
概要
カプトプリルは、スルフヒドリル基を持つ第一世代のアンジオテンシン変換酵素（ACE）阻害薬です。元々は南米のクサリヘビの毒から分離されたペプチドに由来し、最初のACE阻害薬として歴史的に重要な意味を持ちます。
うっ血性心不全（CHF）や高血圧の治療における血管拡張薬として有効ですが、半減期が短く（多くの場合1日3回の投与が必要）、副作用（特に犬における消化器症状）の発生率が高いため、現在獣医療ではエナラプリルやベナゼプリルなどの新しい薬剤にほぼ取って代わられています。
臨床のポイント：エナラプリルとは異なり、カプトプリルはそれ自体が活性薬物であり、効果を発揮するために肝臓で活性代謝物に変換される必要はありません。
作用機序
Captopril acts as a competitive inhibitor of angiotensin-converting enzyme (ACE), for which it has a much higher affinity than the natural substrate, angiotensin-I.
- Angiotensin I → (blocked by ACE) → Angiotensin II (a potent vasoconstrictor).
- The reduction in Angiotensin II leads to vasodilation, decreasing total peripheral resistance, pulmonary vascular resistance, and blood pressure.
- Decreased Angiotensin II also reduces aldosterone secretion, leading to decreased sodium and water retention, while increasing plasma renin activity.
- Cardiovascular benefits in CHF include increased cardiac output, stroke volume, and exercise tolerance with little to no change in heart rate.
安全性・警告
禁忌
- Hypersensitivity to ACE inhibitors
有害事象
- Hypotension
- Renal failure
- Hyperkalemia
- Vomiting
- Diarrhea
- Skin rashes (reported in humans, not dogs)
- Neutropenia/agranulocytosis (rare, reported in humans)
注意事項
Use with caution and under close supervision in patients with renal insufficiency; doses may need to be reduced.
Use cautiously in patients with hyponatremia or sodium depletion, coronary or cerebrovascular insufficiency, preexisting hematologic abnormalities, or collagen vascular diseases (e.g., SLE).
Patients with severe CHF should be monitored very closely upon initiation of therapy to prevent profound hypotension.
Reproductive Safety: Captopril crosses the placenta. High doses in rodents caused decreased fetal weights and increased mortality. Use during pregnancy only when potential benefits outweigh risks (FDA Category C for 1st trimester; Category D for 2nd/3rd trimesters). Enters milk at ~1% of maternal plasma concentrations.
医薬品相互作用
Reduced oral absorption of captopril; separate dosing by at least two hours.
Concomitant use has caused neurologic dysfunction in human patients.
Digoxin levels may increase 15-30%; monitor serum digoxin levels.
Concomitant use may cause hypotension; titrate dosages carefully.
May reduce the clinical efficacy of captopril when used as an antihypertensive agent.
Increased risk of developing hyperkalemia.
Can decrease renal excretion of captopril, possibly enhancing clinical and toxic effects.
Concomitant use may cause additive hypotension; titrate dosages carefully.
監視
- Clinical signs of CHF (respiratory rate/effort, exercise tolerance)
- Blood pressure (especially if treating hypertension or if signs of hypotension arise)
- Serum electrolytes (monitor for hyperkalemia)
- Renal panel (Creatinine, BUN)
- Urine protein
- CBC with differential (periodic)
薬物動態
半減期
吸収
In dogs, ~75% of an oral dose is absorbed, but food in the GI tract reduces bioavailability by 30-40%.
分布
Distributed to most tissues (excluding the CNS). Approximately 40% bound to plasma proteins in dogs. Crosses the placenta and enters milk.
代謝
Metabolized in the liver.
消失
More than 95% of a dose is excreted renally, both as unchanged drug (45-50%) and as metabolites. Half-life is significantly prolonged in patients with renal dysfunction.
過剰投与
The primary concern in an overdose situation is hypotension.
- Treatment: Supportive treatment with volume expansion using normal saline is recommended to correct blood pressure.
- Toxicity thresholds: Dogs given 1.5 g/kg orally developed emesis and decreased blood pressure. Dogs receiving doses greater than 6.6 mg/kg q8h may develop renal failure.
製品
製剤
- Oral Tablets
- Oral Suspension (compounded)
ヒト用医薬品
- Captopril Oral Tablets: 12.5 mg, 25 mg, 50 mg, & 100 mg (Capoten®, generic)
- Captopril and Hydrochlorothiazide Oral Tablets: 15mg/25mg, 15mg/50mg, 25mg/25mg, 25mg/50mg (Capozide®, generic)
規制ステータス
規制データなし: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
保管・安定性
Store tablets in tight containers at temperatures not greater than 30°C. Compounded oral suspension (0.75 mg/mL in Ora-Plus/Ora-Sweet) retains >90% potency for 14 days at 5°C and 7 days at 25°C; protect from light.
飼主向け情報
重要：食事により吸収が著しく低下するため、獣医師の指示がない限り空腹時（食前1時間または食後2時間）に投薬してください。
- 獣医師の許可なく、急に投薬を中止したり減量したりしないでください。
- 重度または持続的な嘔吐や下痢が見られる場合は、危険な脱水症状や低血圧を引き起こす可能性があるため、すぐに獣医師に連絡してください。
- 無気力、脱力感、または状態の悪化の兆候（低血圧や心疾患の悪化を示す可能性があります）がないか、ペットを観察してください。
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