Reserpine, a root extract of the naturally occurring plant Rauwolfia serpentina, was used in the past as a first-line therapy for reducing blood pressure. Nowadays, it is used less commonly as a second-line treatment. This review aimed to assess reserpine's efficacy as a first-line agent in reducing blood pressure in primary hypertension. The method involved finding and summarising the best existing evidence from randomised controlled trials. We considered the quality of the included studies to be reasonable, with acceptable randomisation and blinding methods overall, as shown in the 'Risk of bias' graphs. We noted a weakness when the studies did not provide a detailed description of the methods or results, thus, introducing potential reporting bias arising from selective reporting or other biases, such as lack of concealment of allocation. To ensure we include only good-quality evidence, we only rated a study highly if there was clear evidence that all efforts had been made to ensure neither the participant nor the clinician or assessors were aware of what drug the participant was taking, through concealment of allocation and blinding throughout the study.
This systematic meta-analysis concluded that reserpine is effective in reducing systolic blood pressure as a first-line agent. The degree of this effect was mild to moderate. Because the four included studies did not investigate a wide range of doses, no data were available to infer a dose-related response in blood pressure. Insufficient data were available to evaluate the adverse effects of reserpine therapy. This update did not reveal new studies; as such, the conclusions of this review remain unchanged and represent the most up-to-date evidence, current to October 2016.
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.
Many antihypertensive agents exist today for the treatment of primary hypertension (systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg, or both). Randomised controlled trials (RCTs) have been carried out to investigate the evidence for these agents. There is, for example, strong RCT evidence that thiazides reduce mortality and morbidity. Some of those trials used reserpine as a second-line therapy. However, the dose-related blood pressure reduction with this agent is not known.
The primary objective of this review was to quantify the dose-related efficacy of reserpine versus placebo or no treatment in reducing systolic blood pressure (SBP) or diastolic blood pressure (DBP), or both.
We also aimed to evaluate the dose-related effects of reserpine on mean arterial blood pressure (MAP) and heart rate (HR), as well as the dose-related effects on withdrawals due to adverse events.
We searched the Cochrane Hypertension Group Specialised Register (January 1946 to October 2016), CENTRAL (2016, Issue 10), MEDLINE (January 1946 to October 2016), Embase (January 1974 to October 2016), and ClinicalTrials.gov (all dates to October 2016). We also traced citations in the reference sections of the retrieved studies.
Included studies were truly randomised controlled trials (RCTs) comparing reserpine monotherapy to placebo or no treatment in participants with primary hypertension.
We assessed methods of randomisation and concealment. We extracted and analysed data on blood pressure reduction, heart rate, and withdrawal due to adverse effects.
We found four RCTs (with a total of 237 participants) that met the inclusion criteria, none of which we found through the 2016 update search. The overall pooled effect demonstrates a statistically significant systolic blood pressure (SBP) reduction in participants taking reserpine compared with placebo (weighted mean difference (WMD) -7.92, 95% confidence interval (CI) -14.05 to -1.78). Because of significant heterogeneity across the trials, a significant effect in diastolic blood pressure (DBP), mean arterial pressure (MAP), and heart rate (HR) could not be found. A dose of reserpine 0.5 mg/day or greater achieved the SBP effects. However, we could not determine the dose-response pattern because of the small number of trials. We did not combine data from the trial that investigated Rauwiloid against placebo 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.