高血壓 (vasodilator) Moderate to severe hypertension.

Hydralazine hydrochloride is a vasodilating agent. It reduces peripheral resistance and blood pressure as a result of a direct vasodilatory effect on vascular smooth muscle; the effect on arterioles is greater than on veins.

Hydralazine hydrochloride is rapidly absorbed from the GI tract and is extensively metabolized in the GI mucosa during absorption and on first pass through the liver. After oral administration of a single dose of hydralazine, the antihypertensive effect begins in 20–30 minutes and lasts 2–4 hours. Hydralazine appears to readily cross the placenta. Approximately 85–87% of hydralazine in the blood is bound to plasma proteins following administration of usual doses. Hydralazine is metabolized extensively in the GI mucosa during absorption and in the liver by acetylation, hydroxylation, and conjugation with glucuronic acid. Hydralazine is rapidly excreted in urine, mainly as metabolites. Approximately 10% of an oral dose is excreted in feces. he plasma half-life of hydralazine generally is 2–4 hours, but may be up to 8 hours in some patients.

Coronary artery disease, hypersensitivity, mitral valve rheumatic heart disease.

C

Safe; the milk/plasma ratio is 1.4, no adverse effect reported.

GI disturbance, anorexia, palpitation, tachycardia, angina pectoris, and headache.

PO: Adults: 10-50mg QID, up to 300 mg/day. Children: 0.75 mg/kg/day initially in 4 divided doses; the initial dose should not exceed 25mg, increase gradually to a MAX of 5(infants)- 7.5 (children) mg/kg/day or 200mg/day.