Initial Data Suggests Oxymorphone Immediate-Release Effective for Acute Pediatric Postoperative Pain

BALTIMORE, Md.—Oxymorphone immediate-release is generally well tolerated in children, but a single dose ≤10 mg may not provide analgesia for up to 6 hours in some patients, results from the first part of a two-part study have found.

Matthew S. Wieman, MD, of Endo Pharmaceuticals Inc., Chadds Ford, Pa., and colleagues reported initial data from an ongoing multicenter, open-label, ascending-dose study in which 22 patients aged 12 to 17 years received single oral doses of oxymorphone immediate-release 5 mg or 10 mg following discontinuation of postoperative parenteral analgesia. Pharmacokinetics were monitored for 24 hours and all adverse events were recorded. Patient pain was evaluated at 15 minutes, 30 minutes, and 1, 2,3, 4, and 6 hours postdose using a 100 mm Visual Analog Scale (VAS).

Oxymorphone plasma concentrations were found to be similar to those in adults. Nine patients experienced adverse events; 5 patients in the oxymorphone immediate-release 5 mg group and 4 patients in the oxymorphone immediate-release 10 mg group. Only 2 patients experienced treatment-related adverse events, which were gastrointestinal (i.e., nausea and vomiting).

Seven of 13 patients in the oxymorphone immediate-release 5mg group completed the study and reported a >50% reduction in VAS-rated pain intensity within 30 minutes postdose, which remained mild throughout 6 hours. Mean VAS pain intensity scores declined from 56.0 mm at baseline to 22.6 mm after 6 hours (P=0.02) All patients who received oxymorphone immediate-release 10 mg discontinued due to lack of efficacy.

The first part of the study will continue with an assessment of single-dose oxymorphone immediate-release at a dose of 15 mg. The second part will assess multiple doses of the opioid every 4 to 6 hours for up to 48 hours at an initial dose selected based on single-dose results. Up to 3 doses will be studied in ascending order based on safety and efficacy results for the previous dose, investigators told attendees at the 29th Annual Scientific Meeting of the American Pain Society.