Efficacy of Songling Xuemaikang Capsule on Essential Hypertension, as Monitored on Ambulatory Basis: A Systematic Review and a Meta-Analysis of Randomized Controlled Trials (RCTs)

Objective: To investigate the efficacy of Songling Xuemaikang Capsule (SXC) on essential hypertension, as monitored on ambulatory basis. Methods: Relevant randomized controlled trials (RCTs) were obtained via a systematic search of several databases. The results were pooled with a randomized or a fixed-effect model, according to the heterogeneity. The Cochrane risk of bias assessment tool was used for quality assessment. Results: Thirteen RCTs with 1092 essential hypertension (EH) patients were included in the meta-analysis. Compared with Losartan, SXC was less effective at reducing 24-hour average systolic blood pressure (ASBP, weighted mean difference (WMD): 1.80 mmHg, p = 0.04). SXC combined with other anti-hypertensives significantly reduced ADBP (average diastolic BP) during the daytime (WMD: -1.24 mmHg,p < 0.0001) and systolic blood pressure variability (SBPV) during the nighttime (SMD: -0.58, p < 0.00001), compared to anti-hypertensives alone. Subgroup analyses showed that the combination of SXC and Amlodipine achieved significantly better control of 24-hour ASBP and ADBP (p < 0.05) compared to Amlodipine alone. The combination of SXC and an angiotensin converting enzyme inhibitor (ACE!) achieved significantly better control of 24-hour ASBP and ASBP during both the daytime and nighttime, compared to ACE! alone (p < 0.01). Conclusions: The combination of SXC and Amlodipine Besylate significantly reduced 24-hour ASBP and ADBP. Due to the modest quality of the RCTs included in this meta-analysis, more rigorously designed studies are needed.