Fourteen individuals with essential hypertension (systolic ≥140 mm Hg and/or diastolic ≥90 mm Hg) referred by local general practitioners entered and completed the study. Patients had not received previous treatment or treatment had been stopped for at least 4 weeks or 8 weeks for patients using diuretics before the study. We excluded individuals with secondary cause of hypertension, malignant hypertension, renal failure, ischemic heart disease, cerebrovascular disease, pregnancy, diabetes mellitus, or those who were using oral contraceptives or any other drugs. The study was approved by the local hospital ethics committee. All subjects gave written informed consent. There were 11 men (9 white) and 3 women (2 white). Mean age was 51±9 years and average body mass index was 29.9±5.0 (kg/m2).
The study was designed as a randomized crossover study. After baseline assessments, which included blood pressure, body weight, plasma and urinary electrolytes, individuals were randomized to receive either Potassium Chloride, 96 mmol/d (12 Slow-K tablets), or potassium citrate, 96 mmol/d (34 mL potassium citrate liquid). After 1 week on this treatment, individuals then crossed over to receive the other treatment for 1 additional week. There was a 1-week washout between the 2 treatment periods. All subjects were advised to maintain their dietary habits and lifestyle, and to avoid intense physical exercise throughout the study. Blood pressure was measured in the same arm using an automatic digital blood pressure monitor (Omron HEM-705CP) after 5-minute rest in sitting position.8 Three readings of blood pressure were taken at 1- to 2-minute intervals and the mean of 3 readings was used in the data analysis. Two 24-hour urine collections were obtained at entry to the study, after 1 week on potassium chloride and after 1 week on potassium citrate.
Results are reported as mean±SD. Paired t tests were used to compare the difference in continuous variables between 2 study periods. Statistical analyses were performed using Statistical Package for Social Science.
At baseline, blood pressure was 151±16/93±7 mm Hg with a 24-hour urinary potassium excretion of 81±24 mmol. During the randomized crossover part of the study, blood pressure was 140±12/88±7 mm Hg with a 24-hour urinary potassium of 164±36 mmol on day 7 of potassium chloride, and blood pressure was 138±12/88±6 mm Hg with a 24-hour urinary potassium of 160±33 mmol on day 7 of potassium citrate. These blood pressures were significantly lower compared with that at baseline; however, there was no significant difference in blood pressure between Potassium Chloride and potassium citrate (Figure; mean difference: 95% confidence interval, 1.6; range, −2.3 to 5.6 mm Hg; P=0.385 for systolic; range, −2.4 to 3.7 mm Hg; P=0.653 for diastolic blood pressure).
