A Cochrane review included 2 studies with a total of 79 subjects. One study, with 41 participants, compared cyclobenzaprine with clonazepam and with placebo. Participants taking cyclobenzaprine had some improvement of pain intensity compared to those on clonazepam, mean difference (MD) -0.25 (95% CI -0.41 to -0.09; P value 0.002) and placebo, MD -0.25 (95% CI 0.41 to -0.09; P value 0.002). The other study, with 38 participants, compared cyclobenzaprine with lidocaine infiltration. Thirty days after treatment there were statistically non-significant differences between comparison groups, favoring lidocaine infiltration, for the mean for global pain, MD 0.90 (95% CI -0.35 to 2.15, P value 0.16), and for the mean for pain at digital compression, MD 0.60 (95% CI -0.55 to 1.75, P value 0.30). There were no life-threatening adverse events associated with the medications.
Comment: The evidence is downgraded by imprecise results (few studies and wide confidence intervals) and by indirectness (differences in reported outcomes). Both studies included used different diagnostic criteria for MP.