Thursday, October 27, 2005

New Agent for Postop Nausea?

One of my patients' biggest fears is postoperative nausea and vomiting (PONV) -- often times, a bigger concern than postoperative pain. This is rarely a worry of patients who have never had surgery, but is seen in some who have had prior postop PONV issues. It is also a problem for surgeons; I particularly do not want a patient to start to wretch after a fundoplication or major laparotomy. A large number of medications, solo or in combinations, have been used through the years to try to prevent this problem --- a better approach than trying to treat it once it has been established. At the most recent American Society of Anesthesiologists meeting in Atlanta, yet another class of medications was presented as a potential remedy, NK-1 receptor antagonists. The study came from the Duke University Dept. of Anesthesiology, and found that:

Compared to existing drugs, the NK-1 receptor antagonist blocks at a different site the cascade of biological signals leading to nausea and vomiting. Specifically, 95 percent of patients taking the NK-1 receptor antagonist before surgery did not experience vomiting 24 hours after surgery, compared to 74 percent for the most commonly used drug, ondansetron. The results were similar 48 hours after surgery, 93 percent vs. 67 percent.
NK-1 is also known as Substance P. The trial was funded by Merck Research Laboratories, the developer of NK-1 receptor antagonist known generically as aprepitant; it is not actually new, and has been available for treatment of chemotherapy-related nausea for a while.

I hope that this newer drug is shown to be useful in more trials, as I have been terribly unimpressed with the effectiveness of the most commonly used agent, Zofran (which I have found to be poor in the postoperative setting). In fact, over the past few years I have become more convinced that cheap, good old dexamethasone, in combination with lower doses of more commonly used antiemetics, is more effective at prevention of PONV than higher doses of those newer agents alone.