Transdermal clonidine (TTSC) has been proposed as a means to improve compliance to treatment of hypertensive patients because of the reported 7-day duration of its antihypertensive effect. However, no detailed information is available on the onset, the time course, and the day and night distribution of this effect throughout the 7 days of the drug skin application. In 12 hospital inpatients with mild or moderate untreated essential hypertension, 24-h blood pressure (BP) was measured at 10-20 min intervals via a noninvasive automatic device (Spacelabs 5300 M) in a no-drug condition, on the 2nd, 4th, and 7th day of the arm application of a 7.0 or 10.5 cm2 patch of TTS clonidine, and on the 2nd and 4th day after substitution of the TTS clonidine patch with an identical patch containing an inert substance (placebo). In nine out of 12 patients, TTS clonidine reduced 24-h systolic and diastolic blood pressure at the 2nd day and even more so on the 4th and 7th day of its application. The reduced blood pressure values observed on the 7th day increased progressively on the 2nd and 4th day after TTS clonidine removal with no rebound over the pre-drug values. The hypotensive effects observed during TTS clonidine were evident throughout the day and night. Thus TTS clonidine exerts a hypotensive effect that starts early and is maintained throughout the 7 days and nights of its application. The discontinuation of this treatment is associated with a smooth return of blood pressure values towards the pre-treatment levels.
Address correspondence and reprint requests to G. Mancia at Istituto di Clinica Medica Generale e Terapia Medica, Cattedra di Semeiotica Medica, Università di Milano, Milan, Italy.
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