Open experience with a new myorelaxant agent for low back pain.

INTRODUCTION Eperisone hydrochloride has been recently proposed as a muscle relaxant for the treatment of muscle contracture and chronic low back pain (LBP) as it is devoid of clinically relevant sedative effects on the central nervous system (CNS). We tested this hypothesis by performing a study of patients with LBP and muscle contracture who were treated with full-dose eperisone. METHODS Patients with moderate to severe, acute, or relapsing LBP received eperisone 100 mg three times daily for 10 consecutive days. Assessments included: spontaneous pain, pain on movement, resistance to passive movement, antalgic rigidity, and tolerability. RESULTS In total, 100 patients were enrolled into the study. The treatment achieved a consistent analgesic and muscle relaxant activity across all patients. Both spontaneous pain and pain on movement were significantly decreased, as was resistance encountered by the investigator to passive movements, antalgic rigidity, and muscle contracture. As a consequence, treatment with eperisone resulted in a lower rigidity of the lower back and an improved motility for patients. Only seven adverse reactions were reported, including light-headedness (1), occasional vertigo and/or loss of equilibrium (3), mild somnolence (2), and epigastric pain (1). In almost all cases, there was no need to interrupt the treatment and the adverse reaction resolved spontaneously. CONCLUSIONS Eperisone had an analgesic and muscle relaxant effect in patients with LBP. It should be noted that while it is common practice in rheumatology to combine a pain killer with a muscle relaxant in order to achieve a satisfactory result on both symptoms, the present results with eperisone were achieved with a single drug. With an improved tolerability profile compared with nonsteroidal anti-inflammatory drugs, and a lack of significant adverse effects on the CNS, eperisone hydrochloride represents a valuable alternative to traditional analgesics and muscle relaxants for the treatment of LBP.