Abrupt and gradual change from clonidine to beta blockers in hypertension.

Elective change of antihypertensive therapy from clonidine to beta-blockers was studied in 18 hypertensive inpatients on diuretic treatment. An abrupt cessation of clonidine (0.3 mg t.i.d.) and start of treatment 12 hours later with atenolol (50 mg b.i.d.) resulted, within 24-36 hours, in severe rise of blood pressure and intolerable symptoms of clonidine withdrawal in all 4 patients studied. Plasma noradrenaline levels were elevated 18-24 hours after the last dose of clonidine. Halving the previous daily clonidine dose (0.15 mg t.i.d.) and discontinuing it after three days on concomitant treatment with atenolol or timolol in increasing doses proved successful and caused only few side-effects in 14 hypertensive inpatients.