Comparative study of the effect of azepexole and clonidine on blood pressure and pulse rate in normotensive subjects.

In a double-blind cross-over study in 8 normotensive subjects azepexole was found to have a pharmacological profile identical to that of clonidine, although chemically there is no structural similarity between the two compounds. Compared to placebo, oral azepexole 5 and 10 mg and clonidine 0.15 mg produced a significant reduction in systolic and diastolic blood pressures both supine and standing (tilted). The reduction was greater in the standing than in the supine position. There was a significant slowing of the pulse rate only in the supine position, whereas the reflex increase in pulse rate on tilting was enhanced after both substances. The rise in diastolic blood pressure on tilting, however, was partically blocked by azepexole 10 mg. No dose dependent change in the pulse rate was observed. The maximum fall in blood pressure and pulse rate occurred between 1.5 and 4 h after ingestion of either substance, and had not returned to placebo level after 6 h, except for the supine systolic pressure after azepexole 5 mg. Dose-dependent sedation and dryness of the mouth were observed both after azepexole and clonidine. They followed approximately the same time-course as the haemodynamic changes. Although the hypotensive effect of azepexole 10 mg was larger than that of clonidine 0.15 mg, the orthostatic side-effects were also greater. As the hypotensive effect and side-effects of azepexole 5 mg and 0.15 mg clonidine were almost the same, it seems justifiable to investigate the properties of azepexole in hypertensive patients.