[Clonidine-diuretic combination in patients with essential hypertension. Modification of sympathetic activity and blood pressure as well as the reaction following sudden withdrawal].

In ten patients with essential hypertension, 6 weeks of treatment with a clonidine/diuretic combination (1 retard capsule/day, 75 micrograms or 150 micrograms clonidine, and 15 mg chlortalidon) was suddenly discontinued. The blood pressure, heart rate and sympathetic tone were monitored via the noradrenaline level (NA) in the blood. The six-week treatment with an average of 97.5 micrograms clonidine and 15 mg chlortalidon/day, reduced the NA blood level from 0.48 to 0.37 ng/ml, the blood pressure from 167/102 to 142/86 mmHg, and the heart rate from 73 to 69 bpm. On the second day after termination of therapy, the NA level had increased, on average, 35% above the initial value in 4 out of the 10 patients. In the remaining six patients, the NA level was increased only slightly, and remained markedly below the pre-treatment levels. The blood pressure, however, remained below its initial levels throughout the whole of the two-week observation period. During the phase of increased sympathetic activity, the patients experienced no symptoms. The results show that even after discontinuation of a very low dose of clonidine, some patients can be expected to show a mild increase in sympathetic tone which however would seem to have no clinical significance.