Abstract

A series of 1418 men and 1,347 women with mild hypertension (diastolic phase V 90-109 mm Hg) aged 35-64 who had either had long term antihypertensive treatment with bendrofluazide or propranolol or taken placebo tablets for a similar period were randomly allocated to groups in which their tablets were either stopped or continued. The course of blood pressure and of biochemical variables was followed up for two years. Mean blood pressures rose rapidly after the withdrawal of active treatment, and between nine months and one year after stopping treatment the antihypertensive effect had almost disappeared. The effect persisting longer than this, and possibly due to resetting of the baroreceptors or of other blood pressure control mechanisms, was very small, and as the rise in mean pressure was due to an upward movement in general distribution there was no evidence of a subgroup in whom these mechanisms had been permanently reset to a clinically important extent. After withdrawal of propranolol the rise in pressure was more rapid in younger than in older people. After stopping bendrofluazide pressure rose more rapidly in men who had had higher pressures before and during treatment; this effect was not seen in women. Disturbances in biochemical variables associated with drug treatment had largely resolved by the end of two years after withdrawal. Stopping placebo tablets made no consistent difference to blood pressure.