Thomas R. Collins

February 18, 2010

February 18, 2010 (San Antonio, Texas) — Carisoprodol (Soma) appears to be just as effective in treating acute lower back pain with the 250 mg dose as with the standard 350 mg dose, researchers reported here at the American Academy of Pain Medicine (AAPM) 26th Annual Meeting.

The lower dose was also associated with fewer reports of drowsiness, reported William J. Wheeler, PhD, director of Medical Communication at Meda Pharmaceuticals, in Somerset, New Jersey.

In a prospective double-blind multicenter study, 269 patients received 250 mg carisoprodol and 278 received placebo.

At baseline, the mean Roland-Morris Disability Questionnaire (RMDQ) score (severity scale, 1 to 24, with 24 being maximum disability) was 10.9 in the carisoprodol group and 10.7 in the placebo group. Mean change from baseline was 3.4 (31.1%) with carisoprodol and 1.8 (17.2%) with placebo on day 3.

Patients in the carisoprodol group reported global impression of change scores that improved by about 0.5 on a 0 to 4 scale over baseline, compared with patients in the placebo group (P < .0001). They reported that their backache, specifically, had improved nearly a full point on that scale (P <.0001).

In a second prospective double-blind multicenter trial, 264 patients were treated with 250 mg of carisoprodol, 273 were treated with 350 mg of carisoprodol, and 269 were treated with placebo. The improvements over placebo were not as dramatic, but they were still significant (P < .01).

However, the effects on patients' pain ratings, for both global pain and backache, were nearly the same in the 250 mg group as in the 350 mg group.

"The efficacy of the 250 mg dose was virtually identical to that of the 350 mg dose, so there would actually be no reason to use 350 mg when you could use 250 mg," said Dr. Wheeler.

According to Meda Pharmaceuticals, which was able to regain exclusivity for the drug because of the effectiveness of the lower dose, "if you can get a comparable effect with a lower dose, always use the lower dose."

Researchers also found that 250 mg of carisoprodol yielded good quality-of-life results. Patients scored 31% higher, compared with baseline, on the RMDQ after taking that dose for 3 days. That was compared with a 17% reduction for placebo. A 30% reduction is considered clinically meaningful.

"We've got a clinically important difference in functionality," Dr. Wheeler told Medscape Neurology.

The most common adverse effect with carisoprodol is drowsiness. Patients in the 250 mg group reported drowsiness slightly less often than those in the 350 mg group (13% vs 17%). But there were very slight increases in dizziness and headache, adverse effects that are not as common.

Although it is generally better to prescribe a lower dose than a higher one, the effect on patient care might be slow to develop, said Leonardo Kapural, MD, PhD, director of Pain Management Clinical Research at the Cleveland Clinic in Ohio and AAPM committee member. He said he stopped prescribing carisoprodol many years ago.

Timothy Deer, MD, an AAPM meeting cochair, was hard-pressed to find a major impact, given that the drug is already being used in a larger dose.

The study was funded by Meda Pharmaceuticals. Dr. Wheeler reports being an employee of Meda. Dr. Kapural and Dr. Deer have disclosed no relevant financial relationships.

American Academy of Pain Medicine (AAPM) 26th Annual Meeting: Abstract 156. Presented February 3-5, 2010.


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