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ヒドララジン

Hydralazine

Hydralazine HCl

血管拡張薬POIV犬猫馬

別名: Alphapress · Bionobal · Cesoline · Hydrapres · Hyperex · Hyperphen · Ipolina · Nepresol · Novo-Hylazin · Nu-Hydral · Rolazine · Slow-Apresoline · Supres · apressinum · hydralazini · hydrallazine · Hydralazine hydrochloride · Hidralazina

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

1 mg/kg (starting dose, titrate up to 3 mg/kg if needed)PO· q12h
— 🐕

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
Adjunctive therapy in treatment of heart failure (not receiving ACE inhibitors)1 mg/kg (starting dose, titrate up to 3 mg/kg if needed)POq12h—🌎 NA
Acute, fulminant heart failure due to severe mitral regurgitation (not receiving ACE inhibitors)2 mg/kgPOOnce—🌎 NA
Adjunctive therapy in treatment of heart failure (receiving ACE inhibitors)0.5 mg/kg (starting dose, increase in 0.5 mg/kg increments to max 3 mg/kg)POq12h—🌎 NA
Short-term treatment of CHF secondary to valve diseaseInitial dose of 1 mg/kg PO (additional 0.5-1 mg/kg can be administered to max cumulative 3 mg/kg)POq12hShort-term🌎 NA
Treatment of systemic hypertension (Fifth step drug)0.5 mg/kgPOtwice daily—🌎 NA
Congestive heart failure / Systemic hypertension0.5-3 mg/kgPOq8-12hLong-term🌍 EU
  • Adjunctive therapy in treatment of heart failure (not receiving ACE inhibitors): Effective dose is 0.5-3 mg/kg PO q12h. Titrate upwards carefully. If BP monitored, can titrate more rapidly in 1-2 hour intervals.
  • Acute, fulminant heart failure due to severe mitral regurgitation (not receiving ACE inhibitors): Given along with IV furosemide. May cause hypotension, but benefits outweigh risks.
  • Adjunctive therapy in treatment of heart failure (receiving ACE inhibitors): Give with extreme caution as severe hypotension may occur. Blood pressure monitoring required.
  • Short-term treatment of CHF secondary to valve disease: Goal MAP is 60-80 mmHg. Once desired BP achieved, administer PO q12h.
  • Treatment of systemic hypertension (Fifth step drug): Added if systolic BP > 160 mmHg after enalapril/benazepril, amlodipine (low then high dose), and spironolactone.
  • Congestive heart failure / Systemic hypertension: Start at low dose (0.5-1 mg/kg q12h), monitor blood pressure regularly and increase to 2 mg/kg or even 3 mg/kg q12h if necessary.

猫

適応用量経路頻度期間地域
Adjunctive therapy in treatment of heart failurestart titration at 2.5 mg (total dose) and if necessary, increase up to 10 mgPOq12h—🌎 NA
Treatment of systemic hypertension (Fourth step drug)0.5 mg/kgPOtwice daily—🌎 NA
Systemic hypertension2.5-10 mg/catPOq12hLong-term🌍 EU
  • Adjunctive therapy in treatment of heart failure: Follow similar titration protocols as dogs.
  • Treatment of systemic hypertension (Fourth step drug): Added if systolic BP > 160 mmHg after amlodipine, ACE inhibitor, and spironolactone.
  • Systemic hypertension: Start at low dose and titrate upwards cautiously. Monitor blood pressure regularly.

馬

適応用量経路頻度期間地域
Adjunctive therapy in treatment of heart failure (afterload reducer)0.5 mg/kgIVOnce—🌎 NA
Adjunctive therapy in treatment of heart failure (long-term therapy)0.5-1.5 mg/kgPOq12hLong-term🌎 NA
  • Adjunctive therapy in treatment of heart failure (afterload reducer): ARCI UCGFS Class 3 Drug.

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

ヒドララジン（Hydralazine）は、強力な​直接作用型細動脈拡張薬​であり、主に全身性高血圧の管理や、小動物のうっ血性心不全（CHF）の補助治療における​後負荷軽減薬​として使用されます。

  • ​臨床的有用性​：僧帽弁閉鎖不全症、大きな心室中隔欠損、または重度の動脈弁逆流症の症例において、心臓が血液を送り出す際の抵抗（後負荷）を減らすことが重要であるため、特に有益です。
  • ​難治性心不全​：僧帽弁閉鎖不全症の犬において、ACE阻害薬（エナラプリルなど）で十分な臨床的改善が得られない場合によく使用されます。
  • ​併用療法​：ナトリウムおよび水分の貯留を引き起こす傾向を相殺するために利尿薬と頻繁に併用され、反射性頻脈を抑えるためにβ遮断薬と併用されることもあります。
  • ​制限事項​：有意な弁逆流を伴わず、原発性心筋疾患（拡張型心筋症など）のみが問題である場合、心不全の治療にはあまり有用ではありません。

作用機序

Hydralazine acts as a semicarbazide-sensitive amine oxidase (SSAO) inhibitor, directly relaxing vascular smooth muscle.

  • Mechanism: Alters cellular calcium metabolism in smooth muscle → interferes with calcium movements → prevents the initiation and maintenance of the contractile state.
  • Vascular Selectivity: Exerts a much greater effect on arterioles than on veins. This selective arterial dilation significantly decreases systemic vascular resistance (SVR) and blood pressure.
  • Cardiac Effects: In CHF patients, the reduction in afterload → significantly increases forward cardiac output.
  • Compensatory Responses: In non-CHF hypertensive patients, the sudden drop in blood pressure can trigger baroreceptor-mediated reflex tachycardia and activation of the ​renin-angiotensin-aldosterone system (RAAS)​ → leading to sodium and water retention.

安全性・警告

禁忌

  • Known hypersensitivity to hydralazine
  • Coronary artery disease
  • Hypovolemia
  • Preexisting hypotension
  • Hypovolaemia
  • Renal impairment
  • Cerebral bleeding

有害事象

  • Weakness and lethargy
  • Syncope (fainting)
  • Reflex tachycardia
  • Sodium and water retention
  • GI distress (vomiting, diarrhea)
  • Increased creatinine levels
  • SLE-like syndrome (documented in humans, theoretical in animals)
  • Lacrimation and conjunctivitis
  • Peripheral neuritis
  • Blood dyscrasias
  • Urinary retention
  • Constipation
  • Severe hypotension
  • Anorexia (especially in cats)
  • Vomiting (especially in cats)

注意事項

Dose Titration: Doses must be titrated upwards carefully to avoid severe, life-threatening hypotension.

  • Renal Disease: Use with caution. Reduced renal blood flow can activate the RAAS and exacerbate renal injury; pretreatment with an ACE inhibitor and spironolactone is often advised.
  • Intracerebral Bleeding: Use with caution due to potential effects on cerebral blood flow.
  • Autoimmune Disease: Use cautiously in patients with preexisting autoimmune diseases, as an SLE-like syndrome has been documented in humans.
  • Pregnancy: FDA Category C (humans); Papich Class B (veterinary). Safe for use if used cautiously, but crosses the placenta. Excreted in milk but generally considered compatible with nursing.

医薬品相互作用

ACE-INHIBITORS

May cause additive hypotensive effect; usually used for therapeutic advantage

BETA-BLOCKERS

May cause additive hypotensive effect; usually used for therapeutic advantage

DIAZOXIDE

Potentially could cause profound hypotension

DIURETICSModerate

May cause additive hypotensive effect; usually used for therapeutic advantage

FUROSEMIDE

Hydralazine may increase furosemide's renal effects

MAO INHIBITORS

May cause additive hypotensive effect

SYMPATHOMIMETICS (e.g., epinephrine)

Hydralazine may cause decreased pressor effect and may cause additive tachycardia

ACE inhibitors (e.g., enalapril, benazepril)Major

Enhanced hypotensive effects

AnaestheticsModerate

Enhanced hypotensive effects

Beta-blockers (e.g., propranolol)Moderate

Enhanced hypotensive effects

Calcium-channel blockers (e.g., diltiazem, verapamil)Moderate

Enhanced hypotensive effects

CorticosteroidsMinor

Enhanced hypotensive effects

NSAIDsModerate

Enhanced hypotensive effects

Sympathomimetics (e.g., phenylpropanolamine)Moderate

May cause tachycardia

Adrenaline (Epinephrine)Moderate

Reduced pressor response to adrenaline

監視

  • Baseline thoracic radiographs
  • Mucous membrane color and capillary refill time
  • Serum electrolytes and creatinine
  • Arterial blood pressure (Target MAP 60-80 mmHg for short-term CHF treatment)
  • Venous PO2
  • Occasional CBC (due to possibility of blood dyscrasias)
  • Systemic blood pressure (frequent monitoring during initiation)
  • Heart rate and rhythm
  • Renal function (BUN, Creatinine)
  • Hydration status and body weight (to monitor for fluid retention)

薬物動態

半減期

猫Unknown犬2-4 hours

吸収

Rapidly absorbed after oral administration. Onset of action within 1 hour, peak effects at 3-5 hours. High first-pass effect. Food decreases oral bioavailability in dogs by about 63% (though some reports suggest food may enhance tablet bioavailability).

分布

Widely distributed in body tissues. Approximately 85% bound to plasma proteins in humans. Crosses the placenta and very small amounts are excreted into milk.

代謝

Extensively metabolized in the liver. N-acetylation is a primary enzymatic pathway, which is mostly absent in dogs, leading to increased risks for toxicity.

消失

Approximately 15% is excreted unchanged in the urine. Duration of action in dogs after oral administration is reportedly 11-13 hours.

過剰投与

Clinical Signs: Overdoses are characterized by severe hypotension, reflex tachycardia or other arrhythmias, skin flushing, and myocardial ischemia.

Treatment:

  • Decontamination: Evacuate gastric contents and administer activated charcoal using standard precautions if ingestion was recent and cardiovascular status is stable.
  • Cardiovascular Support: Treat shock using volume expanders. Avoid pressor agents if possible.
  • Pressor Agents: If required to maintain blood pressure, use a minimally arrhythmogenic agent (e.g., phenylephrine or methoxamine).
  • Additional Support: Digitalis agents may be required. Diligently monitor blood pressure and renal function.

製品

製剤

  • Oral tablets
  • Injection
  • 25 mg oral tablet
  • 50 mg oral tablet

ヒト用医薬品

  • Hydralazine HCl Oral Tablets: 10 mg, 25 mg, 50 mg & 100 mg (Apresoline, generic)
  • Hydralazine Injection: 20 mg/mL in 1 mL vials (generic)
  • Apresoline 25 mg tablets
  • Apresoline 50 mg tablets

規制ステータス

European Union✗ 未承認処方箋医薬品EMA

POM (Prescription Only Medicine). Used under the cascade.

United Kingdom✗ 未承認処方箋医薬品VMD

POM (Prescription Only Medicine). Used under the prescribing cascade.

規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU

保管・安定性

Store tablets in tight, light-resistant containers at room temperature. Store injectable product at room temperature; avoid refrigeration or freezing. When mixed with infusion solutions, a color change may occur over 8-12 hours, which does not necessarily indicate a loss in potency.

飼主向け情報

ヒドララジンは、血圧を下げ、ペットの心臓の負担を軽減するための薬であり、特に心臓弁膜症を患っているペットに有用です。

  • ​指示の厳守​：効果を最大限に引き出し、危険な血圧低下を防ぐため、必ず獣医師の指示通りに投薬してください。
  • ​注意すべき症状​：ペットが異常に無気力になったり、虚弱、元気消失、または失神した場合は、直ちに獣医師に連絡してください。これらは血圧が下がりすぎている（低血圧）サインの可能性があります。
  • ​副作用​：軽度の嘔吐や下痢が見られることがあります。これらの症状が続く場合は、獣医師に相談してください。
  • ​食事​：食事が薬の吸収量に影響を与える可能性があるため、この薬を食事と一緒に与えるべきかどうか獣医師に確認してください。

VetSheet医薬品リファレンスは獣医専門家の臨床意思決定支援を目的としており、専門的判断または製造業者の最新医薬品情報の代替にはなりません。