Hydralazine pharmacological effects

Two types of adverse effects occur after the use of hydralazine. The first, which are extensions of the pharmacological effects of the drug, include headache, nausea, flushing. 

Pharmacology Hydralazine exerts a peripheral vasodilating effect through a direct relaxation of vascular smooth muscle. 

In therapeutic doses, hydralazine produces little effect on nonvascular smooth muscle or on the heart. Its pharmacological actions are largely confined to vascular smooth muscle and occur predominantly on the arterial side of the circulation venous capacitance is much less affected. Because cardiovascular reflexes and venous capacitance are not affected by hydralazine, postural hypotension is not a clinical concern. Hydralazine treatment does, however, result in an increase in cardiac output. This action is brought about by the combined effects of a reflex increase in sympathetic stimulation of the heart, an increase in plasma renin, and salt and water retention. These effects limit the hypotensive usefulness of hydralazine to such an extent that it is rarely used alone. 

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