Long-term efficacy and tolerability of a fixed-dose combination of antihypertensive agents: an open-label surveillance study in China.

Background: A fixed-dose combination (FDC) of four compounds, hydrochlorothiazide 12.5 mg, triamterene 12.5 mg, dihydralazine 12.5 mg and reserpine 0.1 mg (HTDR), is widely used as an antihypertensive treatment in China. Although HTDR has been used in China for more than 30 years, there have been few comprehensive evaluations of this treatment.
Objective: The aim of this study was to investigate the long-term efficacy and tolerability of HTDR in Chinese patients with essential hypertension.
Methods: This was a 36-month, community-based, open-label surveillance study, conducted in the Huangpu District (Shanghai, China). The study was based in local primary healthcare settings. Subjects were recruited if they had essential hypertension, were aged ≥35 years at the time of enrolment, were expected to remain in the area for 3 years, and were able to provide informed consent. Patients who had secondary hypertension, myocardial infarction or stroke within 6 months of screening, impaired renal or hepatic function, history of cardiomyopathy or chronic heart failure, or were pregnant or lactating were excluded. HTDR was administered as one or two tablets per day in the morning. If necessary, additional hydrochlorothiazide was added. Blood pressure (BP) was measured at baseline and throughout the 36-month surveillance period every 3 months. Biochemical indicators (e.g. fasting blood glucose, plasma lipid parameters, plasma sodium and potassium, plasma uric acid and serum creatinine) were also measured, and adverse events were noted. BP reductions and the rate at which patients achieved BP targets (systolic BP [SBP] <140 mmHg and diastolic BP [DBP] <90 mmHg) throughout the period were determined. Subgroup analyses by sex and age were also conducted.
Results: A total of 1529 patients (550 male, 979 female; mean age 65.7 years) entered the study. After the 36-month treatment period, 93.1% of patients had achieved the SBP target, 97.9% had achieved the DBP target, and 92.1% had achieved both. The mean decreases in SBP and DBP were 15.3 mmHg and 9.9 mmHg, respectively. Overall, 127 adverse events in 119 patients (7.8%) occurred during the follow-up period, most of which were mild to moderate. Plasma lipid profiles were improved after 24 months of treatment. In addition, a significant increase in plasma potassium and a significant reduction in plasma uric acid were seen.
Conclusion: HTDR was found to have good long-term efficacy and tolerability in Chinese patients with essential hypertension.