Seizure drug Gabapentin lowers postoperative nausea and vomiting risk

"The results support the inclusion of preoperative gabapentin as part of the approach to prevention of PONV," write Dr. Michael C. Grant 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.

Pooled Data Analysis Supports Gabapentin's Antiemetic Effect

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 -- including 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.

Dr. Grant and colleagues also performed a separate analysis of data from eight studies -- including 838 patients -- assessing nausea and vomiting as the main outcome of interest. This 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 percent lower with gabapentin, compared to inactive placebo (or other treatments). The individual risks of nausea and vomiting were reduced by about 66 percent 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 were also similar on analysis of different subgroups, including patient considered at high risk of nausea and vomiting. Gabapentin also reduced the need for other antiemetic (anti-nausea) drugs.

There was evidence of a possible side effect of gabapentin, with a 20 percent increase in the risk of excessive sedation or sleepiness after surgery. It was unclear whether this led to adverse outcomes, such as prolonged time in the postanesthesia care unit (recovery room) after surgery.

Despite progress in identifying risk factors and effective treatments, nausea and vomiting continues to be a common complication of anesthesia and surgery. Originally developed as an anticonvulsant drug, gabapentin has also been found useful for treatment of chronic pain.

Research has shown that gabapentin can be an effective part of strategies to control pain after surgery -- particularly in reducing the need for opioid (narcotic) pain relievers. Experience showing that gabapentin can reduce chemotherapy-related nausea led to its being studied for prevention of nausea and vomiting.

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," Dr. Grant and coauthors conclude. They point to the need for further studies to compare gabapentin to more traditional antiemetic drugs, as well as to understand "the actual mechanism by which gabapentin preempts nausea and vomiting."