We compared patient-controlled analgesia (PCA) and continuous infusion (CI) morphine delivery in a randomized controlled trial in adolescents during oropharyngeal mucositis pain after bone marrow transplantation. Results from 20 patients who completed 7 or more days on study (10 PCA, 10 CI) were evaluated. The group means for age, weight and height were comparable. Daily measures were morphine intake, self-report of pain intensity and side effect scores. Over 10 study days, the mean cumulative morphine dose to subjects in each group was 4.94 mg/kg (PCA) vs. 12.17 mg/kg (CI); the difference is significant (P less than 0.01). No significant differences were found between the groups for patient ratings of pain intensity or side effect scores despite the large difference in mean morphine intake, but the PCA group tended to report less intense sedation and less difficulty concentrating. Adolescents can use PCA effectively and safely for 1-3 weeks. Morphine intake of adolescent patients using PCA morphine intake is significantly lower than that of similar patients receiving staff-controlled CI.
We measured the pharmacokinetics of hydromorphone in normal volunteers given three doses of the drug (10, 20, and 40 micrograms/kg) as intravenous 45-s injections on different days. Concentrations of hydromorphone in plasma from serial blood samples were measured by a high-performance liquid chromatography method specific for hydromorphone with a detection limit of 0.1 ng/mL. In all cases, plasma hydromorphone concentration versus time data for individual subjects were best described by a triexponential (instead of mono- or biexponential) function. Furthermore, we found that the pharmacokinetics of hydromorphone was independent of dose across the range studied. Averaged across doses, the distribution and terminal elimination half-lives were 1.27 min (t1/2 pi), 14.7 min (t1/2 alpha), and 184 min (t1/2 beta), respectively. Average values for systemic clearance, initial dilution volume, and steady-state volume of distribution were 1.66 L/min (Cl), 24.4 L (Vc), and 295 L (Vdss). Our results indicate that hydromorphone pharmacokinetic parameters are linear across a fourfold range of doses that are usually employed clinically and that previously reported pharmacokinetic values for hydromorphone (based on radioimmunoassay measurements) deserve reconsideration.
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