See pharmacokinetic sections in hydralazine and isosorbide dinitrate monographs of Davis's Drug Guide for Nurses for more information.Absorption: Hydralazine—10–26% absorbed in HF patients, absorption can be saturated leading to large increases in absorption with higher doses; isosorbide dinitrate—variable absorbed (10–90%) reflecting first-pass hepatic metabolism.

Distribution: Hydralazine—widely distributed, crosses the placenta, minimal amounts in breast milk; isosorbide dinitrate—accumulates in muscle and venous wall.

Metabolism and Excretion: Hydralazine—mostly metabolized by GI mucosa and liver; isosorbide dinitrate—undergoes extensive first-pass metabolism in the liver mostly metabolized by the liver, some metabolites are vasodilators.

Half-life: Hydralazine—4 hr; isosorbide dinitrate—2 hr.

TIME/ACTION PROFILE ( effect on BP)