Source: Am J Med Genet  |  Posted 7 years ago

By Mike Fillon

NEW ORLEANS, LA -- October 19, 2004 -- Patients who undergo knee arthroscopy can achieve good control of with mild to moderate pain with the new low-dose, oral formulation of oxymorphone hydrochloride immediate release (IR) 5 mg without taking rescue analgesics.

Results of a study that compared the efficacy and safety of the narcotic analgesic oxymorphone immediate release (IR) 5 mg with placebo for mild to moderate pain following the knee surgery were presented here October 14th at the 17th World Conference of Family Doctors, being held in conjunction with the American Academy of Family Physicians Scientific Assembly.

According to lead researcher Joseph Gimbel, MD, Medical Director at Arizona Research Center, Phoenix, Arizona, previous studies used intravenous formulations of oxymorphone at higher doses of 10, 20 and 30 mg.

The randomized, double-blind study included 122 men and women who were 18 years of age and had initial mild to moderate pain (30-70 mm on a 100-mm Visual Analog Scale) following outpatient knee arthroscopy.

The researchers enrolled patients who did not take any other pain medications, minor tranquilizers, muscle relaxants, or dextromethorphan-containing agents 12 to 48 hours prior to surgery. They also did not take monoamine oxidase inhibitors within 2 weeks, or tricyclic antidepressants, serotonin reuptake inhibitors or amphetamines within 4 weeks of surgery.

Patients were randomized to either placebo or oxymorphone IR 5 mg and could administer treatment as needed once per hour for up to 8 hours (8 dose maximum). Pain levels were assessed at 30 minutes, 1 hour, and hourly up to 8 hours.

Before each dose, patients recorded their worst pain, least pain, average pain, and pain at that time. The sum of pain intensity difference (VAS) over 0 to 8 hours was -4.2 (plus/minus 180.8) for placebo and 74.8 (plus/minus 127.4) for oxymorphone IR (P =.007). The mean pain intensity differences (VAS) were statistically significant for 8 of 9 time points between 0 and 8 hours.

In contrast to placebo patients, most patients receiving oxymorphone IR did not require rescue pain medication (P =.0001), and 47% rated oxymorphone IR "very good," or "excellent" for pain relief compared with 25% of placebo patients.

Most adverse events were similar in type and frequency between treatment groups; no patients taking oxymorphone IR discontinued because of adverse events. Low dose oxymorphone IR provided safe and effective treatment for mild to moderate acute pain in ambulatory patients.

"Oxymorpone is more potent than morphine," Dr. Gimbel said. "So if you can give it in a lesser dose it gives the physician another choice -- in terms of pain medications post-operatively -- that's very effective for pain."

Partial financial support for the study was provided by Endo Pharmaceuticals, Inc. Chadds Ford, Pennsylvania.

[Presentation title: "Safety and Efficacy of Low-Dose Opioid Treatment in Ambulatory Patients Following Knee Arthroscopy: A Randomized Controlled Trial with Oxymorphone Immediate Release 5 mg." Poster SE 187]