HYDROMORPHONE ANALGESIA AFTER INTRAVENOUS BOLUS ADMINISTRATION

This study investigated the analgesic effects of three intravenous bol us doses of hydromorphone (10, 20, 40 mu g/kg) on experimental pain me asures in normal humans. Ten healthy male volunteers participated in f our study sessions, one for each of the hydromorphone doses as well as a placebo (saline). They received the four treatments in counterbalan ced order under double-blind conditions and with study days at least 1 week apart, During each session subjects underwent repeated electrica l tooth pulp stimulation at intensities sufficient to elicit a rating of 'strong pain' before drug administration. Subjective pain reports ( PRs) and dental evoked potential amplitude measures (EPs) served as an algesic effect indicators. We observed dose-dependent analgesia as mea sured by both PR (P = 0.009) and EP (P = 0.017), Area under the PR ver sus time curve as well as the EP versus time curve decreased in a log dose-dependent fashion. Although the peak effect was poorly defined, t he onset of analgesia was rapid, within 5 min, and maximum analgesic e ffect was seen between 10 and 20 min after maximum plasma hydromorphon e concentration. However, within sessions we found a poor corresponden ce between hydromorphone plasma concentration and effect. Compared to pain report data from other human studies done in our laboratory, hydr omorphone has a shorter time to peak effect compared to morphine, and overall, hydromorphone hydrochloride is approximately five times as po tent as morphine sulfate on a milligram basis. (C) 1997 International Association for the Study of Pain. Published by Elsevier Science B.V.