Class: Alpha- and beta-adrenergic blocker

Description

Labetalol is a competitive alpha1-receptor blocker as well as a nonselective beta-receptor blocker used to lower blood pressure in a hypertensive crisis. Because of alpha- and beta-blocking properties, blood pressure is reduced without reflex tachycardia, and total peripheral resistance is decreased without a significant alteration in cardiac output. In emergency care, labetalol is administered intravenously.

Onset & Duration

Onset: Within 5 min

Duration: 3-6 hr

Indications

Hypertension

Contraindications

Bronchial asthma Congestive heart failure

Second- and third-degree heart block Bradycardia

Cardiogenic shock

Adverse Reactions

Headache Dizziness Ventricular dysrhythmias

Hypotension Dyspnea Allergic reaction

Facial flushing Diaphoresis Postural hypotension

Drug Interactions

Bronchodilator effects of beta-adrenergic agonists may be blunted by labetalol.

Nitroglycerin may augment hypotensive effects.

How Supplied

100 mg in 20 ml of solvent ampoule (5 mg/ml)

Dosage and Administration

Adult: 5-20 mg slow IV over 2 min; additional injections of 1 0-40 mg can be given at 1 0-min intervals prn

Infusion: Mix 200 mg in 250 ml D5W (0.8 mg/ml); infuse at a rate of 2 mg/min, titrate to supine blood pressure.

Pediatric: Safety has not been established.

Special Considerations

Pregnancy safety: Category C.

Blood pressure, pulse rate, ECG should be continuously monitored. Observe for signs of congestive heart failure, bradycardia, bronchospasm. Labetalol should only be administered with the patient in a supine position.