By Emma Hitt, PhD
HONOLULU -- January 30, 2009 -- Oxymorphone extended release (ER) appears effective and tolerable over the long-term for the treatment of cancer pain, according to findings of a 1-year extension study.
Study author Lynn Quaranta, PharmD, Clinical Affairs Manager at Endo Pharmaceuticals, Chadds Ford, Pennsylvania, presented the findings on January 29 here at the American Academy of Pain Medicine (AAPM) 25th Annual Meeting.
Oxymorphone ER is a long-acting semisynthetic mu-opioid receptor agonist formulated to provide a consistent 12-hour dosing interval and is indicated for the relief of moderate to severe pain in patients requiring continuous, around-the-clock opioid treatment for an extended period.
Oxymorphone ER in short-term trials, given over 1 to 2 weeks, has demonstrated efficacy in relieving cancer-associated pain.
In their 1-year extension study, Dr. Quaranta and colleagues from Endo Pharmaceuticals enrolled 80 cancer patients with moderate to severe pain who had completed a short-term study of oxymorphone ER.
Treatment in the extension trial began with the final dose of oxymorphone ER used in the first trial, at the investigator's discretion, and was titrated to an optimal dose. Patients could also receive oxymorphone immediate release as a rescue medication.
Oxymorphone ER appeared to provide consistent pain relief for most patients throughout the study. Treatment withdrawal occurred in 8.8% of patients due to lack of efficacy and in 25% due to adverse events (most commonly cancer progression). Pain relief continued in the 32.5% of patients who completed the 1-year treatment period.
Mean dose of immediate-release oxymorphone remained at 10% to 15% of the total dose throughout the study. Mean oxymorphone ER dose ranged from about 90 to 145 mg/day, increasing over the course of the study.
Of the patients, 36.3% experienced at least 1 treatment-related adverse event, but 76.7% were mild to moderate. The most common adverse events included dry mouth and constipation, each occurring in 5% of patients.
Oxymorphone ER has a prolonged action of 12 hours, which is longer than many other opioids, Dr. Quaranta noted.
He added, "Each patient has distinct genetic polymorphisms that influence response to different opioids, even though they are within the same class, and it is useful to have multiple treatment options."
Funding for the study was provided by Endo Pharmaceuticals, Inc.
[Presentation title: Long-Term Effectiveness and Tolerability of Oxymorphone Extended Release in Cancer Patients. Abstract 212]
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