[Clinical and biological manifestations following the interruption of prolonged treatment with clonidine].

In 7 out of 14 patients there were marked subjective symptoms following the interruption of prolonged treatment with clonidine. A significant increase in blood pressure, systolic and diastolic, heart rate and urinary catecholamine excretion was seen in the majority of cases. The clinical and biological manifestations would appear to reflect a phenomenon of derepression of sympathetic activity: the increase in urinary catecholamines is the biological result. The findings are of practical importance since they indicate that the interruption of anti-hypertensive therapy with clonidine must be under taken with caution, i.e. progressively.