Influence of food on the bioavailability of "real" and "apparent" hydralazine from conventional and slow-release preparations.

The influence of concomitant food intake on the bioavailability of hydralazine was studied in healthy volunteers following single-dose administrations in the fasting state and together with a standardized breakfast meal of 1840 kJ (440 kcal). Both "real" (presumably active) and "apparent" (= total = "real" hydralazine + acid-labile hydrazones formed after hydralazine ingestion) hydralazine were determined by gas chromatography. Concomitant food intake seemed to enhance the bioavailability of both "apparent" and "real" hydralazine following ingestion of conventional hydralazine tablets. On the other hand, food intake did not significantly affect hydralazine bioavailability from a slow-release preparation. The enhanced effect of food on hydralazine bioavailability from the conventional preparation is probably due to reduced first-pass metabolism.