SUMMARY: The ideal
drug therapy for treating POI would selectively antagonize the inhibitory effects on the gastrointestinal (GI) tract of all of the potential factors implicated in the pathophysiology of POI (neurogenic, inflammatory, hormonal, and pharmacologic mediators). The most promising target to date is inhibition of the adverse GI effects of endogenous and exogenous
opioids. Selective inhibition of the
mu-opioid receptors in the GI tract, without reversing centrally mediated
opioid-induced
analgesia, may be beneficial in reducing POI. The nonselective
opioid antagonists naloxone and
nalmefene have not been studied for POI, and they cross the blood-brain barrier. Therefore, they are not appropriate for preventing or treating POI. The peripherally selective
opioid antagonist methylnaltrexone shortens the duration of POI and the hospital
length of stay (LOS).
Alvimopan, a more extensively studied peripherally selective
opioid antagonist, has been shown to reduce the duration of POI, frequency of
postoperative nausea and vomiting, and hospital LOS. Both
methylnaltrexone and
alvimopan also appear effective for treating
opioid-induced constipation. Preliminary results of a long-term study of
alvimopan safety have revealed some potential concerns, and the significance of the adverse effects must be understood before the most appropriate role of
alvimopan in patient care can be determined. Restricting the prescribing of new POI
drug therapies to certain types of patients, surgeries, and prescribers; incorporating these
therapies into preoperative and postoperative policies, procedures, and protocols; and the potential cost savings from reducing hospital LOS are among the considerations in adding these agents to health-system formularies.
CONCLUSION: