Phenyramidol in acute conditions of lumbago, integumental pain and musculo-skeletal pain: an open label, noncomparative, multi-center study

Objective: To assess the safety and efficacy of phenyramidol hydrochloride tablets in acute conditions of lumbago, integumental pain and musculo-skeletal pain. Methods: This open label, noncomparative, phase IV study recruited adult patients with acute lumbago, integumental pain and musculoskeletal pain who gave written informed consent. Those with elevated liver enzymes, or on analgesics, muscle relaxants, tranquilizers, anti-coagulants, or anti-epileptics were excluded as were pregnant/lactating women. 1 to 2 tablets of 400 mg phenyramidol were given orally 2 to 3 times daily for 3 to 7 days. Safety measures included complete blood count (CBC); liver and renal function tests; electrocardiogram (ECG); global assessments and adverse events. Efficacy measures included change in numerical pain rating scale (NPRS) score and global assessments. Results: 100 patients completed the study. There were no serious adverse events (SAEs) or deaths. The mean (SEM) reduction in the total white blood cell count [0.27 (0.13) thou/µL, P , 0.05] and the mean (SEM) increase in the serum glutamic pyruvic transaminase (SGPT) level [8.78 (3.40) U/L, P , 0.05] were not clinically significant at the end of the treatment period. Investigators’ assessment of safety was: 80% – excellent, 13% – good, 7% – fair. Tolerability grading by patients was: 53% – excellent, 34% – good, 12% – fair; 1% – poor. Out of the total 12 adverse events (AEs) recorded in 11% patients, 7 were clinical, while 5 were laboratory-related pertaining to increased liver enzymes (5%). The average NPRS score showed an improvement of 68% (P , 0.0001). Investigators assessed 89% patients to have clinically meaningful improvement, patients’ assessment of efficacy was: excellent – 43%; good – 38%; fair – 15%; poor – 4%. Conclusion: Phenyramidol is effective and well-tolerated in acute lumbago, musculoskeletal pain and integumental pain when given for up to 7 days. However it should be used with caution in patients with liver disease and with drugs known to cause liver damage.