Transdermal clonidine in mild hypertension. A randomized, double-blind, placebo-controlled trial

In 30 patients with mild essential hypertension, clonidine hydrochloride was delivered from a skin patch reservoir designed to release medication at a constant rate for seven days. After a four-week washout period, patients were randomized (double-blind) into a clonidine- or a placebo-treated group. Clonidine or placebo was then given for five weeks, followed by a two-week washout period to assess withdrawal from treatment. Blood pressure was controlled in 11 of 15 clonidine-treated patients but in only four of 15 placebo-treated patients. The clonidine-treated group evidenced larger decreases in both systolic and diastolic blood pressures. In the clonidine-treated group, blood pressures and plasma clonidine levels were stable throughout a representative seven-day period. Besides mild skin irritation with both clonidine and placebo patches, few side effects were observed. After discontinuation of clonidine administration, plasma levels declined in a non-log linear manner. There was no rebound hypertension. The results suggest that clonidine delivered transdermally is safe and effective for control of mild essential hypertension.