Effect of selected drugs on arterial pressure response to upright posture.

Orthostatic hypotension may be secondary to a variety of factors, prominent among which is administration of drugs effecting autonomic function. Therapy of orthostatic hypotension has been successful using a directly acting sympathomimetic amine, ethylnorphenylephrine, which has a distinctive spectrum of alpha, beta1, and beta2 adrenergic agonist properties. The directly acting vasoconstrictor, dihydroergotamine, is effective, producing hemodynamic patterns reflecting a selective effect on capacitance vessels. Orthostatic hypotension secondary to the administration of L-dopa should usually respond to peripheral decarboxylase inhibition by agents such as alpha-methyldopahydrazine. The combined administration of monoamine oxidase inhibitors with indirectly acting sympathomimetic amines will increase arterial pressure, but must be considered quite risky in light of inherently poor ability to regulate dose-response relationships and prior clinical experience with excessive arterial pressure elevation.