Transdermal clonidine therapy in elderly mild hypertensives: effects on blood pressure, plasma norepinephrine and fasting plasma glucose.

Twenty patients aged 60-74 years entered a study on the effect of transdermal clonidine (Catapres-TTS) as monotherapy for mild hypertension [diastolic blood pressure (DBP) 90-104 mmHg]. Seventeen patients (85%) had a positive therapeutic response (DBP reduced to less than 90 mmHg or by greater than or equal to 5 mmHg). Patient acceptance was high and side effects mild; however, one-quarter of the patients experienced localized skin reactions. A slight increase in fasting plasma glucose level (mean delta = 20 mg/dl) was consistently observed. Transdermal clonidine led to a sustained decline in plasma catecholamine levels although this effect did not seem to be closely related to the observed decreases in blood pressure. Three out of four evaluable patients had a blood pressure 'overshoot' upon discontinuation of therapy to levels above pretreatment values. Transdermal clonidine appears to be effective and generally well tolerated in the treatment of mild hypertension in the elderly; however, more studies designed to investigate effects on glucose tolerance and the possible existence of a rebound syndrome are needed.