By Emma Hitt, PhD
HONOLULU -- January 30, 2009 -- Carisoprodol 250 mg tablets taken 4 times daily appear to improve functional status and are well tolerated in patients with acute, muscle spasm of the lower back, according to research presented here at the American Academy of Pain Medicine (AAPM) 25th Annual Meeting.
Carisoprodol is a centrally acting skeletal-muscle relaxant indicated for the relief of discomfort associated with acute, painful musculoskeletal conditions in adults.
Lee Ralph, MD, San Diego Sports Medicine and Family Health Center and University of California San Diego School of Medicine, San Diego, California, presented the findings here at a poster session on January 30.
"We are interested in getting people with low-back pain -- often weekend warriors or athletic types -- better quickly, and our data showed that carisoprodol achieved improvements almost twice as fast as placebo," Dr. Ralph said in an interview during the poster session.
Carisoprodol was compared with placebo in a multicentre trial of 562 patients aged 18 to 65 years with moderate to severe back pain. A questionnaire, using a score ranging from 1 to 24, assessed the level of disability on days 3 and 7 of the study.
In 488 patients who completed the study, the mean change in disability level from baseline was 3.5 for carisoprodol compared with 1.6 for placebo on day 3 and 6.3 compared with 4.0 on day 7, respectively (P < .001 in favour of carisoprodol on both days).
Treatment-emergent adverse events were observed to a greater extent with carisoprodol than placebo and included drowsiness (13.4% vs 4.6%), dizziness (9.7% vs 3.2%), and headache (3.6% vs 1.4%).
"In general, we don't know how the skeletal-muscle relaxants work or where they work in the pain pathway, but they typically sedate the patient," Dr. Ralph said. "We were surprised though to find that the rate of sedation was low with carisoprodol -- sedation was reported in only 13% of patients."
He added that a metabolite of carisoprodol -- meprobamate -- which has anxiolytic properties, has been a concern with respect to the use of this agent in addictive patients. However, carisoprodol 250 mg produces a relatively low level of meprobamate and is used for a very short time, he said. "Although caution is warranted, the abuse potential of carisoprodol does not appear to be a major concern in this setting."
Funding for this study was provided by Meda Pharmaceuticals.
[Presentation title: Improvement in Functional Status With Carisoprodol 250-mg Tablets in Patients With Acute Lower Back Spasm: A Randomized, Double-Blind, Placebo-Controlled Trial. Abstract 231]
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