Cyclobenzaprine (CBZ)

Cyclobenzaprine is a muscle relaxant medication used to relieve skeletal muscle spasms and associated pain in acute musculoskeletal conditions. It is the best-studied drug for this application, it has also been used off-label for fibromyalgia treatment. A new bedtime formulation of cyclobenzaprine is under development for the management of fibromyalgia syndrome. Cyclobenzaprine has major contraindications with monoamine oxidase inhibitors (MAOIs). At least one study also found increased risk of serotonin syndrome when cyclobenzaprine was taken with the serotonergic drugs duloxetine or phenelzine. Cyclobenzaprine has been found to be non-inferior to tizanidine, orphenadrine, and carisoprodol in the treatment of acute lower back pain, although none have been proven to be effective for long term use. No differences in pain or spasm scores were noted among these agents, nor when compared to benzodiazepines.