Captopril-induced creatine kinase elevations: a possible role of the sulfhydryl group.

To THE EDITOR: Since captopril, the first orally active angiotensin converting enzyme inhibitor, was introduced into clinical medicine, this new approach to blocking the formation of angiotensin II and lowering the blood pressure, appears to be tolerated well in most hypertensive patients. However, during a randomized trial comparing the antihypertensive efficacy of captopril, 25 mg b.i.d., with captopril, 25 mg t.i.d., we found elevated creatine kinase (CK; EC 2.7.3.2) levels in several patients. In the present study, therefore, CK levels in 44 patients with mild to moderate hypertension (24 men and 20 women; average age, 53.5 ± 2.0 [S.E.] years) treated with captopril were reviewed retrospectively. Thirty of these patients were treated with captopril alone, while 14 were treated with captopril in addition to other hypotensive agents: diuretics in eight, /3-blockers (atenolol) in two, diuretics with /3-blockade in three (atenolol in one, propranolol in two) and nifedipine in one. The duration of treatment ranged from 1 to 26 months. The average captopril dosage was 60.7 mg/day and ranged from 25 to 75 mg/day. (Unless otherwise specified, all data are expressed as means ± SE.)