Evaluation of eperisone hydrochloride in the treatment of acute musculoskeletal spasm associated with low back pain: A randomized, double-blind, placebo-controlled trial

Background: Eperisone hydrochloride is a centrally acting muscle relaxant inhibiting the pain reflex pathway, having a vasodilator effect. Aims: To evaluate the efficacy and tolerability of eperisone in patients with acute musculoskeletal spasm associated with low back pain. Settings and Design: Prospective, randomized, double-blind, placebo-controlled, multicentric trial conducted at five tertiary care orthopedic centers across India. Materials and Methods: It was planned to enroll 240 patients of either sex between 18-60 years with acute musculoskeletal spasm (AMSP) with low back pain (LBP) due to spondylosis deformans, prolapsed disc or muscle sprain. Patients with other associated unrelated spasm conditions were excluded. Assessments were done for finger-to-floor distance (FFD), lumbar pain, Lasegue's sign, tenderness of vertebral muscles, need for rescue medication and response to therapy for efficacy and tolerability. Statistical Analysis: Parametric data were analyzed by 't' test and ANOVA, and non-parametric data were analyzed using Mann-Whitney 'U' test and Kruskall-Wallis test. Proportions were compared using Fischer's (Chi-square) test. Results: Two hundred and forty patients were randomized to receive eperisone 150 mg/day in three divided doses (n = 120) or placebo (n = 120) for 14 days, of which 15 patients did not complete and 225 patients completed the study (eperisone, 112 and placebo, 113). Significantly greater improvement in FFD (P < 0.001) from baseline on Day 14 was seen with eperisone (150.66 to 41.75) compared to placebo (138.51 to 101.60). Improvements in other parameters were greater with the eperisone group. For 89 (79.46%) patients the therapy was rated as good-excellent with eperisone compared to 43 (38.05%) patients with placebo. Nausea, abdominal pain, headache and dizziness were the common adverse events with both therapies. Rescue drug was needed by 40 (35.71%) eperisone patients and 83 (73.45%) placebo patients. Conclusions: Eperisone hydrochloride was effective and well tolerated for the treatment of patients with AMSP with LBP.