Effects of diltiazem on catecholamines in hypertensive patients

The in vivo effects of calcium channel blocker, diltiazem, on reflex sympathetic activity [assessed indirectly by 24 hour urinary VMA] were determined in this study. Twenty four hour urinary vinyl mandelic acid [VMA] was estimated before and two weeks after the administration of diltiazem in hypternsive patients and control normotenisve subjects. The urinary VMA concentration though somewhat increased remained within the normal range, showing that reflex sympathetic activity was neither too high to interfere with antihypertensive effect of the drug nor too low to cause postural hypotension