多巴酚丁胺
**多巴酚丁胺 (Dobutamine)** 是一種合成的兒茶酚胺，為快速作用的注射型正性肌力藥物。 主要臨床特點包括： - **主要用途：** 用於急性心臟衰竭（如擴張性心肌病）和心因性休克的短期治療。 - **血流動力學支持：** 當單獨使用輸液治療無法恢復可接受的動脈血壓、心輸出量或組織灌注時使用。 - **臨床要點：** 由於其半衰期極短，必須在密切監測的加護病房 (ICU) 環境中以連續靜脈輸注 (CRI) 的方式給藥。與多巴胺不同，多巴酚丁胺不依賴內源性去甲腎上腺素的釋放，因此在兒茶酚胺耗竭的衰竭心臟中更為可靠。
作用機制: 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.
各物種劑量
- 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
給藥途徑
禁忌症
- Known hypersensitivity to dobutamine or the preservative sodium bisulfite
- Idiopathic hypertrophic subaortic stenosis (IHSS)
- Uncorrected hypovolemic states
- Cardiac outflow obstruction (e.g., aortic stenosis)
不良反應
- 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)
藥物相互作用
- 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
監測
- 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
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.
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