Dobutamine
**Dobutamine** is a synthetic catecholamine and a rapid-acting, injectable positive inotropic agent. Key clinical features include: - **Primary Use:** Short-term management of acute heart failure (e.g., dilated cardiomyopathy) and cardiogenic shock. - **Hemodynamic Support:** Used when fluid therapy alone fails to restore acceptable arterial blood pressure, cardiac output, or tissue perfusion. - **Clinical Pearl:** Because of its extremely short half-life, it must be administered as a continuous rate infusion (CRI) in a closely monitored Intensive Care Unit (ICU) setting. Unlike dopamine, dobutamine does not rely on the release of endogenous norepinephrine, making it more reliable in catecholamine-depleted failing hearts.
Mecanismo: 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.
Dosificación por especie
- 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
Vías de administración
Contraindicaciones
- Known hypersensitivity to dobutamine or the preservative sodium bisulfite
- Idiopathic hypertrophic subaortic stenosis (IHSS)
- Uncorrected hypovolemic states
- Cardiac outflow obstruction (e.g., aortic stenosis)
Efectos adversos
- 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)
Interacciones farmacológicas
- 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
Monitoreo
- 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
Sobredosis
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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