An intra-arterial profile of methyldopa

The "Oxford" system for intra-arterial ambulatory blood pressure monitoring was used to monitor the blood pressure profile in 24 patients with essential hypertension who had received no therapy for 4 wk. The responses to tilt and isometric and dynamic bicycle exercise were recorded. Following the baseline study patients received methyldopa 125 mg t.i.d., which was titrated to a maximum of 500 mg t.i.d. according to blood pressure responses. The mean daily dosage was 1359 mg. Six weeks after the last dosage increment the experiment was repeated. Each patient was asked to take the total daily dosage once a day and the intra-arterial monitoring program was repeated after another 6 wk. Mean daytime intra-arterial blood pressure during three-times-daily dosing was reduced by 27/15 mm Hg; circadian curves were clearly separated during the day but not at night. Once-daily dosing did not control blood pressure as well. There was no evidence of postural hypotension and the absolute pressure response was lowered during both isometric and dynamic exercise. These results are comparable to those from similar studies with alpha- and beta-adrenoreceptor--blocking drugs.