Low-dose atenolol-chlorthalidone combination for treatment of mild hypertension

In a randomized, double-blind, within-patient study, 28 out-patients with mild to moderate hypertension were given, at the end of a 3-week placebo wash-out period, four different antihypertensive treatments for 3 weeks each. the treatments were 50 mg atenolol, 100 mg atenolol, 12.5 mg chlorthalidone and a fixed combination of 50 mg atenolol and 12.5 mg chlorthalidone. All treatments were given once daily. Visits were scheduled for the last day of each treatment period, 24-26 hours after the last dose, and there was an intermediary wash-out period between each pair of active treatments. Supine systolic/diastolic blood pressure was 165/102 on placebo, 153/93 mmHg on 50 mg atenolol, 155/91 mmHg on 100 mg atenolol, 148/93 mmHg on 12.5 mg chlorthalidone and 144/89 mmHg on the combination. All the changes in pressure were significant (p less than 0.01) versus placebo. Supine systolic blood pressure was lower on the combination than on 100 mg atenolol alone (p less than 0.05) and upright systolic pressure was lower on the combination than on 100 mg atenolol (p less than 0.05) or 50 mg atenolol (p less than 0.05) alone. The heart rate was lowered by atenolol alone or combined with chlorthalidone but did not fall below 56 bpm in any patient. Serum potassium levels were lower on 12.5 mg chlorthalidone than on placebo (3.88 mEq/l vs 4.09 mEq/l--p less than 0.05) but the difference was trivial; on the combination of atenolol-chlorthalidone there was no significant difference versus placebo (3.97 mEq/l vs 4.09 mEq/l--NS).(ABSTRACT TRUNCATED AT 250 WORDS)