Source: DGNews  |  Posted 2 years ago

By Jennifer Reising

SAN ANTONIO, Tex -- February 9, 2010 -- Subcutaneous methylnaltrexone does not
adversely affect pain control or show any clinically significant increases in
opioid withdrawal symptoms in the treatment of opioid-induced constipation in
patients with chronic, nonmalignant pain, according to a study presented here
at the 26th annual meeting of the American Academy of Pain Medicine (AAPM).

E. Richard Blonsky, MD, Professional Pain & Rehabilitation Clinic of Chicago,
Chicago, Illinois, presented the results of a double-blind, randomised,
placebo-controlled phase 3 study during a poster presentation here on February
3.

The study included 460 patients treated with daily opioids for chronic
nonmalignant pain, who had opioid-induced constipation. Patients were receiving
a daily dose of >=50 mg of oral morphine equivalents for 2 weeks or more.

Patients were randomised to receive 12 mg of injectable methylnaltrexone for 4
weeks either once daily or once every other day or a daily placebo.

Pain intensity was measured at baseline and on days 14 and 28 using an 11-point
Likert scale. Opioid withdrawal symptoms, measured by the Objective Opioid
Withdrawal Scale (OOWS), were evaluated at baseline and on days 1, 14, and 28.
Opioid use was assessed on a daily basis.

Results showed that mean pain intensity scores were similar between all
treatment groups at each double-blind assessment and changed minimally over
time.

There were no significant differences in change between methylnaltrexone taken
once daily and placebo in OOWS total scores on day 14 (0.1 vs 0, respectively)
and day 28 (0 vs 0).

However, on day 1, a statistically significant difference in OOWS total scores
was observed between patients taking methylnaltrexone every other day and
placebo (0.3 vs 0.0; P < .001); however, this was not considered
clinically meaningful.

The average daily use of morphine equivalents changed only slightly over the 4
weeks of double-blind treatment.

“Results from this study suggest that subcutaneous methylnaltrexone used in the
treatment of opioid-induced constipation in patients with chronic, nonmalignant
pain conditions does not affect pain control,” concluded Dr. Blonsky.
“Additionally, the use of methylnaltrexone did not result in clinically
significant changes in the morphine equivalent dose used, and did not
precipitate objective opioid withdrawal symptoms.”

Funding for this study was provided by Wyeth Research, which was acquired by
Pfizer, Inc. in October 2009.

Presentation title: Subcutaneous Methylnaltrexone Treatment for
Opioid-Induced Constipation: Effect on Pain and Opioid Withdrawal Symptoms.
Abstract 193