A comparison of once and twice daily atenolol for angina pectoris

We have studied the effects of four doses of atenolol in 11 patients with stable angina pectoris using a symptom-limited exercise test and angina diaries. The doses 100 mg twice daily and 50 mg, 100 mg and 200 mg once daily were given double-blind and randomised within patients following run-in on placebo. Measurements were made 12 hours after the last twice daily dose and 24 hours after the last once daily dose. Exercise tolerance was improved by 40-74% and exercise duration before the onset of angina by 61-94% (P less than 0.01). Maximal heart rate was reduced further by a total daily dose of 200 mg than by lower doses, but no extra benefit was derived by giving the drug twice daily. The largest increase in exercise tolerance was obtained during treatment with 50 mg once daily. Atenolol was shown to be an effective anti-anginal agent when given once daily, and there were no major differences between the doses studied.