Clonidine effect in chronic angina pectoris. Double-blind, crossover trial on 60 patients.

Increased adrenergic activity, often manifested in chronic angina, is likely to influence adversely the course of the disease. In view of the inhibitory effect of clonidine (CL) upon the adrenergic nervous system, the effectiveness of small doses of CL in chronic angina was evaluated in a double-blind crossover study on 60 patients suffering at least 5 coronary pains per week in spite of routine medication. CL was given orally in a dose of 2 x 75 microgram/day for a 2 wk. Reduction in frequency of coronary pains by at least 50% was observed in 53.7% of patients, total nitroglycerin consumption decreased from 322 to 174 tablets/week, and ergometric performance increased from 168 to 283 W x min/patient. Urinary excretion of adrenaline and noradrenaline diminished. Blood pressure and heart rate were not considerably changed. Mild and transient side effects occurred in 10 patients, 9 of them completed the trial. It is concluded that CL in low doses is effective and safe in patients with chronic angina, presumably by alleviating adrenergic strain.