Comparison of the analgesic efficacy and tolerability of tramadol 100 mg sustained-release tablets and tramadol 50 mg capsules for the treatment of chronic low back pain

This multicentre, randomised, double-blind, parallel-group study was designed to examine the analgesic efficacy and tolerability of a newly developed tramadol slow-release (SR) tablet in comparison with immediate-release tramadol capsules in patients with chronic low back pain which had persisted despite intervention with other pharmacological and/or nonpharmacological measures. 103 patients were treated with tramadol SR tablets twice daily (2 x 100 mg/day) and 102 patients with capsules 4 times daily (4 x 50 mg/day) over a period of 3 weeks. The medication in both groups (verum/placebo) was administered 4 times daily to ensure the double-blind character of the study ('double-dummy technique'). In case of insufficient pain relief the patients received 2 x 200 mg SR/day as an escape medication (open design). Daily pain intensity was assessed by patients on a 4-step verbal rating scale. At the end of the study retrograde assessment of analgesia was done by the patient using a 5-step classification. Sufficient pain relief could be achieved in approximately 60% of the patients (116 patients) who completed the 3-week treatment period. There was no difference in pain relief (SR 59% and capsules 59%) and in course of pain intensity between both groups. Furthermore, 30 patients (15.3%) were satisfactorily treated with the escape medication. Adverse events were reported at a similar rate in both groups (54.4% with the SR tablet formulation and 52.9% with the capsules). The main adverse events were nausea (l6.6%), dizziness (14.1%), vomiting (9.8%), tiredness (7.8%), diaphoresis (6.3%), headache (6.3%), constipation (6.3%) and dry mouth (6.3%). With the exception of diaphoresis, constipation and dry mouth, adverse events decreased in incidence during the study. The results confirmed the equivalence with regard to efficacy and tolerability of twice-daily administration of tramadol SR tablets compared with 4-times-daily administration of tramadol capsules.