For the prophylaxis of migraine.
Propranolol competes with sympathomimetic neurotransmitters such as catecholamines for binding at beta(1)-adrenergic receptors in the heart, inhibiting sympathetic stimulation. This results in a reduction in resting heart rate, cardiac output, systolic and diastolic blood pressure, and reflex orthostatic hypotension.
Symptoms of overdose include bradycardia, cardiac failure, hypotension, and brochospasm. LD<sub>50</sub>=565 mg/kg (orally in mice).
Propranolol is almost completely absorbed from the GI tract; however, plasma concentrations attained are quite variable among individuals.
4 hours
Propranolol is extensively metabolized with most metabolites appearing in the urine.
* 4 L