[Clonidine transdermal therapeutic system in essential hypertension: effect and tolerance]

The antihypertensive efficacy and side effects of a transdermal therapeutic system containing 2.5 mg clonidine (clonidine-TTS) was investigated in 21 patients with essential hypertension over a period of 10 weeks. The system was designed to release 0.1 mg clonidine/24 h. Mean systolic and diastolic blood pressure fell from 160 +/- 17/106 +/- 7 mm Hg to 139 +/- 16/91 +/- 8 mm Hg after 4 weeks and to 135 +/- 14/89 +/- 8 mm Hg after 10 weeks (p less than 0.001). Sufficient blood pressure control was achieved by one clonidine-TTS weekly in 24% and by 2 clonidine-TTS in 33% of the patients. 43% of all cases required additional oral therapy with 50 mg hydrochlorothiazide/day. However, antihypertensive action was accompanied by a high incidence of local skin reactions. These skin reactions with erythema, itching and red papules occurred in 6 of the 21 patients (29%) after treatment with TTS for at least 4 weeks. Patch testing with the various components of clonidine-TTS in 4 patients identified clonidine-allergy of delayed type in 3 cases. Typical clonidine side effects such as fatigue, dry mouth, constipation and sexual disturbances were moderate. It is concluded that clonidine-TTS has a good and continuous antihypertensive action. However, the high incidence of skin reactions limits its use in the treatment of essential hypertension.