PHARMACODYNAMIC ACTION AND PHARMACOKINETICS OF MOXONIDINE AFTER SINGLE ORAL-ADMINISTRATION IN HYPERTENSIVE PATIENTS

Moxonidine is a new centrally acting alpha2-adrenoceptor agonist that differs from others by a lower incidence of side effects in hypertensive patients. The effects of moxonidine and placebo on blood pressure, pulse rate, plasma catecholamines, plasma renin activity, sedation, and salivary flow were evaluated in eight hypertensive patients by an intraindividual comparison. Moxonidine induced a significant decrease in blood pressure that corresponded with its plasma concentrations. The maximum antihypertensive effect appears to be delayed when compared with the peak plasma level. Plasma norepinephrine, epinephrine, and plasma renin activity were significantly reduced by moxonidine, and blood pressure reduction corresponded with decrease of plasma norepinephrine. Heart rate, sedation, and salivary flow were not different using moxonidine compared with placebo. Only one patient mentioned dry mouth. No further relevant adverse effects were seen in the patients. This study demonstrate a significant decrease of blood pressure, plasma renin activity, norepinephrine, and epinephrine with a single dose of 0.25 mg moxonidine, but no significant effect on pulse rate, salivation, and sedation.