[Effects of rilmenidine on the central nervous system and kidney]

Rilmenidine is an oxazoline with antihypertensive properties characterised by a dissociation of its antihypertensive and central side effects and the absence of tolerance. After a single dose, the antihypertensive activity is directly related to the dose of rilmenidine. Secondary sedative effects and dryness of the mouth are no different to those observed with placebo at doses of 0.5 and 1.0 mg. In two randomised trials versus placebo (N = 126) and versus clonidine (N = 333) in hypertensive patients after a 1 month washout period under placebo, the antihypertensive effect of rilmenidine was superior to placebo and comparable to that of clonidine (0.150 mg once or twice daily). After 4 and 6 weeks' treatment with rilmenidine (1 mg once or twice daily) the average decrease in supine systolic-diastolic BP was 21-15 mmHg and the average percentage of normalised values (diastolic BP less than or equal to 90 mmHg) was 60 per cent. The incidence of somnolence was comparable to that observed with placebo and 2 to 3 times less than that with equihypotensive doses of clonidine. No patients withdrew from the trial because of side effects. The sustained antihypertensive effect in an open trial of 269 patients treated for one year and 134 patients for two years, showed that there was no tolerance with rilmenidine. This result is probably related to the absence of salt and water retention and the conservation of renal function observed in single dose regime in healthy subjects and in chronic administration in hypertensives. No significant changes were observed in renal blood flow, glomerular filtration, filtration fraction, serum or urinary electrolyte concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)