Transdermal clonidine as an adjunct to enalapril: an evaluation of efficacy and patient compliance.

This four-center, 20-week, open-label study evaluated transdermal clonidine as an adjunct to enalapril 10 mg daily and demonstrated patterns of compliance. Seventy-four mildly to moderately hypertensive patients (mean seated blood pressure, 150/101 mm Hg) received enalapril 10 mg once daily as initial monotherapy. In 66 patients, the seated diastolic blood pressure remained greater than or equal to 90 mm Hg at the trough blood levels of enalapril. Transdermal clonidine (3.5 cm2, 7.0 cm2, or 10.5 cm2, equivalent to 0.1 mg, 0.2 mg, and 0.3 mg clonidine/day, respectively) then was added as needed to achieve blood pressure control. Forty-eight patients achieved diastolic blood pressures less than 90 mm Hg on concomitant therapy; 44 patients completed 8 weeks of maintenance dosing with a mean blood pressure of 134/85 mm Hg. Oral compliance, as measured by an electronic device that was actuated each time the medication vial was opened, varied from 48 to 140%. Compliance with the transdermal clonidine regimen was excellent; the patch was worn as directed during 96% of the patient-weeks of therapy. The authors conclude that blood pressure can be controlled by a combination of transdermal clonidine and enalapril in patients that do not adequately respond to enalapril monotherapy. Patients poorly complying with oral regimens may be candidates for a trial of transdermal clonidine monotherapy.