ラミプリル
ラミプリルは、獣医療において主に血管拡張薬として使用される**長時間作用型のプロドラッグ型アンジオテンシン変換酵素（ACE）阻害薬**です。 主な臨床応用は以下の通りです： * **うっ血性心不全（CHF）：** 混合型血管拡張薬（前負荷および後負荷の両方を軽減）として働き、心拍出量と運動耐容能を改善します。 * **全身性高血圧：** 特に猫において、全身の血圧低下を助けます。 * **蛋白漏出性腎症および慢性腎臓病（CKD）：** 糸球体内圧と蛋白尿を減少させ、腎機能の維持に寄与します。 獣医療ではエナラプリルやベナゼプリルがより一般的に使用されますが、ラミプリルは作用時間が長く強力な代替薬となります。英国およびいくつかの欧州諸国で動物用医薬品として正式に承認されています。
作用機序: Ramipril is a pro-drug with minimal intrinsic pharmacologic activity. Upon absorption, it undergoes hepatic de-esterification → **ramiprilat** (the active metabolite). * Ramiprilat competitively binds to **Angiotensin-Converting Enzyme (ACE)**, preventing the conversion of **Angiotensin I** → **Angiotensin II**. * Because Angiotensin II is a potent vasoconstrictor, its reduction leads to **vasodilation** (decreased total peripheral and pulmonary vascular resistance). * Decreased Angiotensin II also reduces **aldosterone** secretion → decreased sodium and water retention, and increased plasma renin activity. * **Renal effects:** ACE inhibitors preferentially dilate the efferent arteriole of the glomerulus → decreased intraglomerular pressure → reduced proteinuria.
動物種別の用量
- Treatment of arterial hypertension · 0.125 mg/kg PO once daily · PO · q24h
- CHF · 0.2 mg/kg PO once daily · PO · q24h · Anecdotal evidence; pharmacokinetic studies are lacking.
- Treatment of heart failure · Initially, 0.125 mg/kg PO once daily; depending on the severity of pulmonary congestion, dose may be increased to 0.25 mg/kg PO once daily · PO · q24h
用量は獣医療従事者向けの臨床リファレンスです。必ず最新の添付文書と個々の患者で確認してください。
投与経路
禁忌
- Hypersensitivity to ACE inhibitors
- Clinical cases of vascular stenosis (e.g., aortic stenosis)
- Obstructive hypertrophic cardiomyopathy
- Concurrent use with potassium-sparing diuretics (per UK label)
有害事象
- Anorexia
- Vomiting
- Diarrhea
- Weakness
- Hypotension
- Hyperkalemia
薬物相互作用
- Aspirin · May potentially negate the decrease in systemic vascular resistance induced by ACE inhibitors (though low-dose aspirin did not affect enalaprilat hemodynamics in one dog study).
- Antidiabetic agents (insulin, oral agents) · Possible increased risk for hypoglycemia; enhanced monitoring recommended.
- Diuretics (e.g., furosemide, hydrochlorothiazide) · Potential for increased hypotensive effects.
- Diuretics, potassium sparing (e.g., spironolactone, triamterene) · Increased hyperkalemic effects; enhanced monitoring of serum potassium required.
- NSAIDs · Potential for increased risk of renal dysfunction or hyperkalemia.
- Potassium supplements · Increased risk for hyperkalemia.
モニタリング
- Clinical signs of CHF
- Serum electrolytes (especially potassium)
- Creatinine and BUN
- Urine protein
- CBC with differential (periodic)
- Blood pressure (if treating hypertension or if clinical signs of hypotension arise)
過量投与
Ramipril appears quite safe in dogs; dosages as high as 1 gram/kg induced only mild GI distress. Lethal doses in rodents are extremely high (10-11 grams/kg). * **Primary concern:** Hypotension. * **Treatment:** Supportive treatment with volume expansion (normal saline) is recommended to correct blood pressure. * **Note:** Because of the drug's long duration of action, prolonged monitoring and treatment may be required.
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。