Blood pressure lowering efficacy of reserpine for primary hypertension.

Many antihypertensive agents exist today for the treatment of primary hypertension (systolic blood pressure >/=140 mmHg and/or diastolic blood pressure >/=90 mmHg). Randomised controlled trials have been carried out to investigate the evidence for these agents.There is, for example, strong RCT evidence that thiazides reduce mortality and morbidity. Reserpine has been used as a second-line therapy in some of those trials. However, the dose-related blood pressure reduction with this agent is not known. To investigate the dose-related effect of reserpine on blood pressure, heart rate and withdrawals due to adverse events. The databases CENTRAL, EMBASE, and MEDLINE were searched. We also traced citations in the reference sections of the retrieved studies. Included studies were truly randomised controlled trials comparing reserpine monotherapy to placebo or no treatment in patients with primary hypertension. Methods of randomization and concealment were assessed. Data on blood pressure reduction, heart rate,and withdrawal due to adverse effects were extracted and analysed. Four RCTs (N =237) were found that met the inclusion criteria. The overall pooled effect demonstrates a statistically significant systolic blood pressure (SBP) reduction in patients taking reserpine compared to placebo (WMD -7.92, 95% CI -14.05, -1.78). Due to significant heterogeneity across trials, a significant effect in diastolic blood pressure (DBP), mean arterial pressure (MAP), and heart rate (HR) could not be found. The SBP effects were achieved with 0.5 mg/day or greater. However, the dose-response pattern could not be determined because of the small number of trials. Data from the trial that investigated Rauwiloid against placebo was not combined with reserpine data from the remaining three trials. This is because Rauwiloid is a different alkaloid extract of the plant Rauwolfia serpentina and the dose used is not comparable to reserpine. None of the included trials reported withdrawals due to adverse effects. Reserpine is effective in reducing SBP roughly to the same degree as other first-line antihypertensive drugs. However, we could not make definite conclusions regarding the dose-response pattern because of the small number of included trials. More RCTs are needed to assess the effects of reserpine on blood pressure and to determine the dose-related safety profile before the role of this drug in the treatment of primary hypertension can be established.