Evaluation of promotility agents to limit the gut bioavailability of extended-release acetaminophen

Background: Erythromycin and neostigmine have both been shown to act as gastrointestinal promotility agents. Objectives: The purpose of this study was to determine whether either erythromycin or neostigmine, administered parenterally, would result in lower serum levels of a recently ingested drug, when compared with placebo. Methods: Ten volunteers ingested 1300 mg of extended-release acetaminophen on each of three occasions. They were then given an intravenous dose of erythromycin (200 mg), neostigmine (2 mg), or placebo. Each volunteer received all three treatments in a counterbalanced fashion, each separated from the next by at least two weeks. Blood for serum acetaminophen concentration was drawn at 1, 2, 4, 6 and 8 h after treatment, and the serum acetaminophen elimination curves were compared for the three treatments. Results: The elimination phase of the curves did not differ among the treatments as a result of administration of the prokinetic agents. Conclusions: Under the present conditions, administration of erythromycin and neostigmine as prokinetic agents failed to alter the kinetics of an ingested dose of sustained-release acetaminophen.