Extended-release tramadol/paracetamol in moderate-to-severe pain: a randomized, placebo-controlled study in patients with acute low back pain.

OBJECTIVE: Combinations of oral analgesics may offer several potential benefits compared with an individual agent. The objective of this study was to investigate the efficacy and safety of an extended-release, twice-daily fixed combination of 75 mg tramadol/650 mg paracetamol (DDS-06C) in the treatment of moderate-to-severe pain, using acute low back pain as a model.

RESEARCH DESIGN AND METHODS: In this phase III study, 277 patients with moderate-to-severe acute low back pain were randomized to 1-2 tablets of DDS-06C or placebo every 10-12 h for 2.5 days during the double-blind phase. Following the double-blind phase, patients had the option to continue for a 2.5-day open-label phase.

CLINICAL TRIAL REGISTRATION: Clinicaltrials.gov (Identifier: NCT00643383)

MAIN OUTCOME MEASURES: The primary end point was the sum of pain intensity differences (SPID) over the 50-h double-blind phase (SPID50). Secondary end points included total pain relief score over the 50-h double-blind phase (TOTPAR50), patient's global impression of medication, and SPID over the first 4 h.

RESULTS: A statistically significant (p = 0.038) greater decrease in pain intensity was observed in the DDS-06C group (median SPID50: -6.0) versus placebo (median SPID50: -4.0). Greater pain relief was also observed in patients randomized to DDS-06C: the median TOTPAR50 was 13.0 for the DDS-06C group and 11.0 for placebo (p = 0.026). DDS-06C demonstrated statistically significant superior efficacy compared with placebo for the majority of the other secondary end points. Overall, 38% of patients treated with DDS-06C experienced at least one adverse event; the intensity was mild-to-moderate in 81% of cases. The most commonly reported adverse events (>5% of patients receiving DDS-06C) were nausea, dizziness, vomiting, and somnolence.

CONCLUSIONS: Using acute low back pain, a model with a high degree of heterogeneity and intrinsic variability, DDS-06C was superior to placebo on measures of pain intensity and relief, and was well-tolerated.