Controlled-Release Oxycodone Fares Well in Phase 3 Chronic-Pain Trial: Presented at WCP

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Title: Controlled-Release Oxycodone Fares Well in Phase 3 Chronic-Pain Trial: Presented at WCP
URL: http://www.pslgroup.com/dg/2299AA.htm
Doctor's Guide
August 22, 2008

By Sara Freeman

GLASGOW, United Kingdom -- August 22, 2008 -- A novel, controlled-release formulation of oxycodone provides effective around-the-clock analgesia to patients with chronic pain due to knee or hip osteoarthritis, according to data from a phase 3 clinical trial presented here at the 12th World Congress on Pain (WCP).

The long-acting formulation of oxycodone -- PTI-821 -- was granted a new drug application by the US Food and Drug Administration earlier this month for treatment of moderate-to-severe chronic pain.

"We believe this phase 3 clinical study is the first to show analgesic efficacy of any twice-daily oxycodone formulation over 12 weeks," stated the researchers, who were led by Nadav Friedmann, Pain Therapeutics, Inc., San Mateo, California.

Dr. Friedman and colleagues included an open-label, 2-week, dose-titration phase to evaluate the drug's tolerability. During this time the dose of oxycodone was titrated from 5 mg to 20 mg twice daily, and patients recorded their level of pain using an interactive voice-recognition system.

Patients in the study had osteoarthritis of the hip or knee and an initial pain intensity score of 5 or greater, as rated on an 11-point numerical rating scale (0 = no pain, 10 = worst pain).

A total of 412 patients entered the randomised, double-blind phase of the study, with 205 continuing to receive the abuse-resistant oxycodone and 207 switched to placebo. To avoid opioid withdrawal, however, placebo-treated patients had their dose of oxycodone gradually tapered over a 4-week period. Patients given the active drug were treated with 20 mg then were titrated up to 40 mg twice daily to achieve optimum analgesic effect.

A similar number of patients in each arm completed treatment, with 70 oxycodone-treated and 75 placebo-treated patients withdrawing from the study early. The main reason for early discontinuation during the double-blind phase was adverse events, with 36.2% and 34.1% of patients withdrawing in each arm, respectively. Adverse events seen in the active treatment arm were typical of opioid therapy and included constipation, somnolence, and nausea. Dry mouth, headache, dizziness, and pruritis were also reported.

Mean pain intensity scores were greatly improved with the controlled-release oxycodone compared with placebo. The area under the curve for the change in pain intensity scores from prerandomisation to the end of 12 weeks of treatment were 59.9 for oxycodone and 30.4 for placebo (P = .007).

Statistically significant reductions in pain intensity were also observed at every postrandomisation time point in the group given controlled-release oxycodone. More favourable responses on the Short Form Health Survey physical component summary score were also observed in oxycodone-treated patients compared with placebo at week 12. Active treatment also improved pain scores obtained using the Western Ontario and McMaster Universities Osteoarthritis Index to a greater extent than placebo.

According to the researchers, controlled-release oxycodone addresses a serious public health need to decrease "abuse, misuse, and diversion of opioid pain relievers," the researchers concluded.

The study was supported by Pain Therapeutics Inc. and King Pharmaceuticals Inc.

[Presentation title: Abuse-Resistant, Long-Acting Oxycodone Treats Chronic Pain in a Large Phase III Study. Abstract PT224]

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