Effect of phenylpropanolamine hydrochloride on blood pressure in Korean patients with hypertension controlled by hydrochlorothiazide.

The effect of 10 oral doses of phenylpropanolamine hydrochloride 25 mg four times a day on blood pressure and heart rate in Korean patients with hypertension controlled by hydrochlorothiazide was studied. A randomized, placebo-controlled, crossover, double-blind study design was used. Twenty Korean patients with mild hypertension controlled by hydrochlorothiazide were recruited from an ambulatory-care clinic. Blood pressure and heart rate were measured in triplicate before treatment, after a five-day washout period between phases of treatment, and two hours after the last dose in each phase of treatment. Eighteen patients completed both phases of treatment, and one patient completed only the placebo phase. Mean baseline values for systolic and diastolic blood pressures and heart rate before the placebo phase did not significantly differ from mean baseline values before the phenylpropanolamine phase. Comparison of mean baseline values for systolic and diastolic blood pressures and heart rate with mean after-treatment values showed no clinically relevant or statistically significant changes for the 19 patients who completed the placebo phase or the 18 patients who completed the phenylpropanolamine phase. There was no significant difference between the mean change in systolic blood pressure, diastolic blood pressure, or heart rate when the phenylpropanolamine phase was compared with the placebo phase. Phenylpropanolamine hydrochloride 25 mg p.o. four times a day (total, 10 doses) given to Korean patients with hypertension controlled by hydrochlorothiazide did not affect blood pressure or heart rate according to single-point outcome measurements.