Carisoprodol is used for the short-term relief of discomfort associated with acute, painful musculoskeletal conditions. The drug is indicated for short-term use only (i.e., up to 2-3 weeks) because adequate evidence of efficacy for more prolonged use has not been established and because acute, painful musculoskeletal conditions generally are of short duration. In addition, long-term use of carisoprodol may increase the risk of abuse, dependence, and tolerance.
Skeletal muscle relaxants generally appear to be more effective than placebo in providing symptomatic relief of acute low back pain, but are associated with a high incidence of adverse effects. Although comparative studies are limited, available data suggest that various skeletal muscle relaxants generally have similar efficacy for such use. Acute low back pain usually is a benign and self-limiting condition that improves spontaneously over time; if pharmacologic therapy is required, an analgesic agent such as acetaminophen or a nonsteroidal anti-inflammatory agent (NSAIA) generally is recommended as first-line therapy for most patients. Skeletal muscle relaxants (alone or in combination with analgesics) may be used as an option for short-term relief of acute low back pain; however, the possibility of adverse effects, particularly adverse CNS effects, should be considered. In general, skeletal muscle relaxants should be used with caution after weighing the potential risks against the benefits in individual patients.
Efficacy of carisoprodol for the relief of acute, painful musculoskeletal conditions was evaluated in 2 randomized, placebo-controlled studies in adults 18-65 years of age with acute, idiopathic low back pain of no more than 3 days' duration. In these studies, patients were randomized to receive carisoprodol (250 or 350 mg) or placebo 3 times daily and at bedtime for 7 days. In both studies, carisoprodol was found to be more effective than placebo, as measured by patient-rated relief from starting backache and patient-rated global impression of change. The 250-mg dosage of carisoprodol was similar in efficacy to the 350-mg dosage, but was associated with a lower incidence of adverse events. Patients receiving carisoprodol in these studies also experienced an improvement in functional status compared with those receiving placebo (as measured by the Roland-Morris Disability Questionnaire score), and clinical improvement was observed regardless of whether patients reported sedation.
Well-controlled clinical studies have not conclusively demonstrated whether relief of musculoskeletal pain by carisoprodol results from skeletal muscle relaxant effects, sedative effects, or a placebo effect of the drug. Most authorities attribute the beneficial effects of carisoprodol to its sedative properties. The drug is ineffective in the treatment of skeletal muscle hyperactivity secondary to chronic neurologic disorders, such as cerebral palsy, and other dyskinesias.