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Labetalol
| Drug | Labetalol |
| Brand names | Trandate ® |
| Indications | Myocardial ischemia. Hypertension. Hypertensive emergency, including in pregnancy. Postoperative hypertension. |
| Mechanism of action | Combined beta-adrenergic and alpha-adrenergic blocker with rapid onset of action. Labetalol has less antihypertensive efficacy as compared with nicardipine. Labetalol is safe in patients with coronary artery disease since it does not increase heart rate, and reduces myocardial oxygen consumption. Time to onset of action: 5 minutes. |
| Effects | Lowers blood pressure, reduces heart rate, myocardial oxygen consumption and myocardial contractility. |
| Time to onset of action | 5 to 10 minutes |
| Duration of action | 2 to 4 hours |
| Delivery | IV |
| Dose | Can be given as repeated intravenous bolus injections or as a constant-dose infusion. Bolus regimen: • 20 mg IV bolus over 2 minutes, followed by 20 to 80 mg every 10 minutes to a total dose of 300 mg. Infusion regimen: • 0.5–2 mg/minute IV infusion. Higher doses are sometimes required. |
| Adverse effects | Vomiting. Dizziness. Nausea. Atrioventricular blocks (AV-blocks). Orthostatic hypotension. Paresthesias (scalp tingling). Bronchospasm. |
| Caution | • Avoided in hypertensive emergencies with left ventricular failure (due to negative inotropic effect). • Used cautiously in patients with asthma (due to risk of bronchospasm). • Used cautiously in bradycardia due to negative chronotropic effect. • In patients with pheochromocytoma, cocaine or methamphetamine overdose, prior treatment with alpha blockade is necessary before administering labetalol (risk of elevating blood pressure in these settings). |