The anticonvulsant medication gabapentin, which already is a useful part of strategies to control pain after surgery, also effectively reduces the common complication of postoperative nausea and vomiting (PONV), reports a study in Anesthesia & Analgesia.
“The results support the inclusion of preoperative gabapentin as part of the approach to prevention of PONV,” write Michael C. Grant, MD, a clinical fellow in the Department of Anesthesiology, and colleagues of The Johns Hopkins Medical Institutions, Baltimore. But they highlight the need for further research, including studies to determine exactly how gabapentin works to prevent nausea and vomiting.
The researchers analyzed pooled data (meta-analysis) from previous randomized trials of gabapentin that provided information on nausea and vomiting outcomes. Most of the 44 studies, which included nearly 3,500 patients, focused on gabapentin’s effects on pain and related outcomes. In these studies, nausea and vomiting were evaluated as secondary outcomes, along with side effects.
Grant and colleagues also performed a separate analysis of data from eight studies, which included 838 patients, assessing nausea and vomiting as the main outcome of interest. This analysis addressed a weakness of previous analyses including all data on nausea and vomiting from gabapentin studies.
Meta-analysis of these primary outcome studies showed reduced rates of nausea and vomiting for patients receiving gabapentin before surgery. The overall risk of nausea and vomiting within 24 hours was about 60% lower with gabapentin, compared to inactive placebo (or other treatments). The individual risks of nausea and vomiting were reduced by about 66% each.
The effects were similar to the results of meta-analysis of all studies, whether nausea and vomiting was evaluated as a primary or secondary outcome. The benefits of gabapentin also were similar on analysis of different subgroups, including patients considered at high risk of nausea and vomiting. Gabapentin also reduced the need for other antiemetic drugs.
There was evidence of a possible side effect of gabapentin, with a 20% increase in the risk of excessive sedation or sleepiness after surgery. It was unclear whether this side effect led to adverse outcomes, such as prolonged time in the postanesthesia care unit after surgery.
The new analysis, including the largest group of studies to date, suggests that gabapentin has a “significant role ... not only for alleviating postoperative pain, but also for preventing PONV,” the authors say.
