RESUMEN
To evaluate the role of endogenous opiates in chemo-therapy-induced nausea and vomiting, the narcotic-antagonist naloxone was administered to six pediatric patients receiving cancer chemotherapy. Naloxone was administered by continuous intravenous (i.v.) infusion after randomized, double-blind controlled assignment at a dose of 0, 10 or 40 micrograms/kg/h for 12 h. Each patient was studied for four consecutive and identical courses of chemotherapy (eight courses for each naloxone dose or 24 courses in all). A dose-related increase in nausea (nausea score 2.5 +/- 2.24, 3.83 +/- 2.73, and 5.75 +/- 2.86/12 h, p = 0.003), vomiting (emetic events 6.0 +/- 7.50, 8.08 +/- 6.71, and 10.3 +/- 8.91/12 h, p = 0.035), and patient aversion (course preference rank 1.5 +/- 0.45, 2.83 +/- 1.17, and 3.25 +/- 0.42/4 courses, p = 0.014) was observed. The infusion of naloxone in the absence of chemotherapy was without effect. These results support a role for endogenous opiates in regulating chemotherapy-induced nausea and vomiting, and further suggest that narcotic agents may be effective antiemetics in this setting.