ドブタミン
**ドブタミン**は合成カテコールアミンであり、速効性の注射用陽性変力薬（強心薬）です。 主な臨床的特徴： - **主な用途：** 急性心不全（拡張型心筋症など）および心原性ショックの短期治療。 - **血行動態サポート：** 輸液療法単独では適切な動脈血圧、心拍出量、または組織灌流を回復できない場合に使用されます。 - **臨床上のポイント：** 半減期が非常に短いため、厳密にモニタリングされた集中治療室（ICU）環境で持続静脈内輸液（CRI）として投与する必要があります。ドパミンとは異なり、内因性ノルエピネフリンの放出に依存しないため、カテコールアミンが枯渇した不全心においてより信頼性が高くなります。
作用機序: Dobutamine acts primarily as a direct **beta1-adrenergic agonist** with mild **beta2-** and **alpha1-adrenergic** effects. **Mechanism Pathway:** **Dobutamine** binds to **beta-1 receptors** on the myocardium → activates **G-stimulatory (Gs) proteins** → stimulates **adenylyl cyclase** → increases intracellular **cyclic AMP (cAMP)** → activates **Protein Kinase A (PKA)** → increases intracellular calcium influx → enhances myocardial contractility (positive inotropy). Unlike dopamine, it does not cause the release of endogenous norepinephrine and lacks dopaminergic receptor activity. It increases cardiac output and stroke volume while decreasing left ventricular filling pressures (wedge pressures), with minimal direct effect on systemic vasculature. Higher doses can induce tachycardia.
動物種別の用量
- Short-term treatment of acute heart failure · 5-15 micrograms/kg/minute IV · IV · CRI · Short-term
- Unspecified cardiac support · 1-3 micrograms/kg/minute IV · IV · CRI
- Unspecified cardiac support · 1-5 micrograms/kg/minute IV · IV · CRI · Start at 1 microgram/kg/minute and titrate until clinical effect.
- Short-term inotropic support (heart failure, shock, anesthesia hypotension) · 1-5 µg/kg/min (start low and titrate up) · IV · CRI · Up to 48 hours · Adverse effects are more commonly seen at doses >2.5 µg/kg/min. Doses over 5 µg/kg/min may cause seizures.
- Unspecified cardiac support · 1-10 micrograms/kg/minute as an IV infusion · IV · CRI · ARCI UCGFS Class 2 Drug
- Hemodynamic support in foals (after volume repletion) · 2-20 micrograms/kg minute CRI · IV · CRI · Another section of this reference states the dose is 3-40 micrograms/kg/minute. Follow the rule of '6': 6 times the weight of foal (in kg) = the number of mg to add to 100 mL of saline (1 mL/hr = 1 microgram/kg/minute).
- Short-term treatment of acute heart failure · 5-40 micrograms/kg/minute IV · IV · CRI · Short-term · Doses of 5-20 micrograms/kg/minute are generally adequate. Infusions >20 micrograms/kg/minute may cause tachycardia.
- Shock where fluid therapy alone not adequate · 5-15 micrograms/kg/minute constant rate IV infusion · IV · CRI
投与経路
禁忌
- Known hypersensitivity to dobutamine or the preservative sodium bisulfite
- Idiopathic hypertrophic subaortic stenosis (IHSS)
- Uncorrected hypovolemic states
- Cardiac outflow obstruction (e.g., aortic stenosis)
有害事象
- Tachycardia
- Facial twitching (especially in dogs)
- Seizures
- Tachyphylaxis (increasing dosages required over time)
- CNS effects such as tremors or seizures (especially in cats at >5 mcg/kg/min)
- Ectopic beats
- Increased blood pressure
- Chest pain and palpitations (reported in humans)
- Proarrhythmia (ventricular arrhythmias)
- Hypertension
- Hypokalaemia (with prolonged use)
- Nausea
- Vomiting
- Seizures (particularly in cats at higher doses)
薬物相互作用
- Halogenated hydrocarbon anesthetics (e.g., halothane, cyclopropane) · May result in increased incidences of ventricular arrhythmias
- Beta-blockers (e.g., metoprolol, propranolol) · May antagonize the cardiac effects of dobutamine, resulting in a preponderance of alpha-adrenergic effects and increased total peripheral resistance
- Nitroprusside · Synergistic effects (increased cardiac output and reduced wedge pressure) can result
- Oxytocic drugs · May induce severe hypertension when used with dobutamine in obstetric patients
- Insulin · Increased insulin requirements in diabetic patients · moderate
- Propranolol · Increased systemic vascular resistance · major
- Doxapram · Increased systemic vascular resistance · moderate
- Selegiline · Increased systemic vascular resistance (MAOI interaction) · major
- Halothane · Increased incidence of arrhythmias · major
- Digoxin · Recommended prior/concurrently in cases of atrial fibrillation to prevent increased ventricular rate · minor
モニタリング
- Heart rate and rhythm (ECG)
- Blood pressure
- Mucous membrane color and capillary refill time
- Urine flow/output
- Central venous or pulmonary wedge pressures (ideally)
- Cardiac output
- Continuous ECG
- Arterial blood pressure (direct preferred)
- Serum potassium levels
- Heart rate and rhythm
過量投与
Clinical signs reported with excessive dosage include **tachycardias**, **increased blood pressure**, **nervousness**, and **fatigue**. Because of the drug's extremely short duration of action, temporarily halting the intravenous infusion is usually all that is required to reverse these adverse 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。