Table 2. Pharmacodynamic Indices after Administration of Immediate- and Sustained-release Hydromorphone

Data are mean ± SD or median and interquartile range. First- and last-time pain tolerance (PT) > 50% peak indicates when at least 50% of the peak pain tolerance was present for the first and for the last time, respectively. Duration PT > 50% peak PT indicates time span that pain tolerance was at greater than 50% of the peak PT.

*P < 0.05, immediate-release hydromorphone (IRH) differed significantly from other treatments, but different doses of sustained-release hydromorphone (SRH) were not significantly different among each other.

NA = not applicable because measured analgesic response after 8 mg SRH was not different from placebo.