Clonidine monotherapy in mild hypertension.

In our study of adolescents with sustained hypertension, single-agent therapy with clonidine significantly reduced blood pressure and heart rate, while hydrochlorothiazide as a single agent significantly reduced only systolic pressure. After 24 weeks of therapy, 40 percent of the diuretic-treated group achieved the treatment goals vs 87 percent in the group treated with clonidine. No alteration of blood chemistry profiles was demonstrated in the clonidine-treated group, with significant hypokalemia occurring during hydro-chlorothiazide therapy. Prior to treatment all participants had repeated blood pressure determinations above the 95th percentile for their age. Their average seated diastolic pressure was in the range of mild hypertension. However, it is possible that their relatively young age at the onset of fixed hypertension imposes a greater risk level. This concern is supported by recent reports demonstrating myocardial hy-pertrophy and altered myocardial function in mildly hyper-tensive adolescents. The cardiovascular hyperresponsiveness to mental stress in these adolescents bears some resemblance to the hyper-kinetic state of borderline hypertension.9 Previous studies have demonstrated a form of impaired neurogenic activity in borderline hypertension.'0 " The effect of the centrally acting agent clonidine on the mental stress response in this study was a reduction in diastolic pressure response and heart rate response to stress, with corresponding reduction in cate-cholamine levels. Catecholamine levels were higher during diuretic treatment.' Therefore, at this age and phase of hypertension, blood pressure control may be more sensitive to the effects of a centrally acting agent. REFERENCES