Songling Xuemaikang Capsule (松龄血脉康胶囊) for primary hypertension : a systematic review of randomized controlled trials

To evaluate the effectiveness and safety of Songling Xuemaikang Capsule (松龄血 脉康胶囊, SXC) for the treatment of primary hypertension. An extensive search including Cochrane Library, PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Chinese Biomedical Literature Database (CBM), Chinese National Knowledge Infrastructure (CNKI), Chinese Scientific Journal Database (VIP), KoreaMed, Japanese database, and online clinical trial registry websites was performed up to February 2013. Randomized controlled trials (RCTs) regarding SXC for the treatment of primary hypertension were searched without no language restrictions. The quality of each trial was assessed according to the Cochrane Reviewers' Handbook 5.0, and RevMan 5.0 provided by the Cochrane Collaboration. A total of 17 RCTs involving 1,778 patients were included. Meta-analysis showed that there was no significant difference between SXC and antihypertensive agents on systolic blood pressure [mean difference (MD): -0.10 [-4.83, 4.63]; P=0.97] and diastolic blood pressure (MD: 1.00 [-1.16, 3.16]; P=0.36), but SXC combined with antihypertensive drugs was more effective in lowering systolic blood pressure (MD: -6.17 [-7.86, -4.49]; P < 0.00001) and diastolic blood pressure (MD: -7.24 [-8.62, -5.85]; P < 0.00001) compared with the antihypertensive drugs alone. SXC used alone or combined with antihypertensive drugs appear to be an effective treatment for lowering elevated blood pressure and improving symptoms in patients with primary hypertension. However, the conclusion cannot be drawn definitely due to the poor quality of the included studies. There is still an urgent need for well-designed, long-term studies to address the benefits of SXC for treating primary hypertension.