Effect of food on oral availability of apresoline and controlled release hydralazine in hypertensive patients.

Hydralazine is a vasodilator antihypertensive drug that has been in use for many years. Efficacy after oral administration correlates well with the levels of the drug in blood. Factors such as food ingestion that affect blood levels of hydralazine may therefore be of importance. There is dispute regarding the effect of food intake on blood levels of hydralazine and on the antihypertensive response. This randomized cross-over study examined the effect of food (642 K calories, 25 g protein, 43 g fat, 40 g carbohydrates, 32 mEq sodium, 17 mEq potassium) ingested immediately before hydralazine (taken as Apresoline, Ciba Geigy, or as slow-release hydralazine, SRH, Pennwalt Corporation) on the blood levels of hydralazine in 16 essential hypertensive patients who were slow acetylators currently taking at least 100 mg Apresoline daily. Peak blood hydralazine levels were reduced by food after both Apresoline and SRH, by 69 and 66%, respectively. Time to peak blood hydralazine concentration was delayed significantly with SRH. We could detect a statistically significant food-related reduction of area under blood hydralazine concentration versus time curves (AUC) only with Apresoline (by 44%). The AUC for SRH was decreased only 29% by food. Hydralazine should be taken at a consistent time with respect to meals.