Muscle Relaxants
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Muscle Relaxants

All Equal and Somewhat Helpful: carisoprodol, methocarbamol, chlorphenesin carbamate, metaxalone, chloroxazone, orphenadrine citrate, diazepam, and cyclobenzaprine. Their mechanisms are not well defined. Most act via selective inhibition of polysynaptic pathways in the central nervous system. Most evidence for their efficacy is based on subjective responses and there is question as to the adequacy of the clinical studies to date. Based on the data all of the relaxants (possibly excepting diazepam) are better than placebo based on subjective analyses. Although combinations with analgesics provide better symptom relief, no superiority over analgesics exists. No skeletal relaxant has been shown to be superior over any other oral relaxant. Cranio 1990 Jul;8(3):234-43 & very similar conclusion in Am J Hosp Pharm 1980 Oct;37(10):1313-23; Metaxalone (Skelaxin 400mg #50=$67 at Osco’s 5/15/03; carisoprodol (Soma) 350mg #100 = $16 (Darby); methocarbamol (Robaxin) 500mg #100 = $17; chlorzoxazone (Parafon Forte DSC) 500mg #100 = $11; cyclobenzaprine (Flexeril) 10mg #100 = $8

Cyclobenzaprine Superior to Benzodiazepine for Jaw Pain; Neither Helped Sleep: DB PC cyclobenzaprine 10 mg HS vs. clonazepam 0.5mg HS for 3 weeks. J Orofac Pain 2002 Winter;16(1):64-70

Cyclobenzaprine Better in Meta-Analysis: Compared to placebo in first 14 days was 5 times more likely to report decrease in back pain. Benefit greatest in first four days. The magnitude of this improvement was modest, with an effect size of 0.38 to 0.58 in all 5 outcomes (local pain, muscle spasm, tenderness to palpation, range of motion, and activities of daily living). Treatment efficacy for these 5 outcomes was greatest early, in the first few days of treatment, declining after the first week. Drowsiness side-effect. Arch Intern Med 2001 Jul 9;161(13):1613-20

Cyclobenzaprine 10HS as Good as 10TID: DB crossover with 15 day washout and 15 day treatment for fibromyalgia in 20 pts. Decline in the number of tender points; significant improvements were also reported in the quality of sleep, anxiety, fatigue, irritable bowel syndrome and stiffness. J Int Med Res 1993 Mar-Apr;21(2):74-80

Cyclobenzaprine Helps in 12 Week Rx of Fibrositis: 12-week, double-blind, controlled trial of 120 patients with fibrositis. Of the patients who received placebo, 52% dropped out due to lack of efficacy of the drug, compared with 16% of patients taking cyclobenzaprine. The dropout rate due to adverse reactions was similar in the 2 groups. Patients taking cyclobenzaprine experienced a significant decrease in the severity of pain and a significant increase in the quality of sleep. There was a trend toward improvement in the symptoms of fatigue, but morning stiffness was not alleviated. These improvements in symptoms were associated with a significant reduction in the total number of tender points and in muscle tightness. Arthritis Rheum 1988 Dec;31(12):1535-42

Cyclobenzaprine Also For Acute Muscle Spasms: Clin Ther 1988;10(2):216-28