The Effects of Food on the Oral Bioavailability of Doxazosin in Hypertensive Subjects

The bioavailability of and pharmacodynamic responses to doxazosin, administered with and without food, were examined in a crossover study in 12 hypertensive subjects. The administration of doxazosin with food delayed its absorption by approximately 1 hour, reduced the maximum (peak) plasma drug concentration after single dose administration (C_max) by 18%, and reduced the area under the plasma concentration-time curve (AUC) by 12%; however, these effects were not statistically significant. The acute fall in blood pressure following doxazosin administration was not significantly affected by food; however, there was a trend towards a lower incidence of complaints in this group. The effect of coadministration of food on the pharmacokinetic and pharmacodynamic responses to doxazosin are unlikely to be of clinical significance.