Evaluation of the Efficacy and Dose-Response Relationship of Dexibuprofen (S(+)-Ibuprofen) in Patients with Osteoarthritis of the Hip and Comparison with Racemic Ibuprofen Using the WOMAC Osteoarthritis Index

Treatment with non-steroidal anti-inflammatory drugs is the most common pharmacological therapy of rheumatic diseases. For the symptomatic treatment of painful disorders a dose-response relationship of the NSAID should be a basic requirement, which is difficult to be proven in studies because rheumatic diseases are heterogenous in terms of clinical involvement. The aim of this double-blind randomized trial was to compare the isolated active enantiomer dexibuprofen (S(+)-ibuprofen) with the double dose of racemic ibuprofen and to show a dose-response relationship of dexibuprofen in painful osteoarthritis of the hip.178 patients were randomly assigned to dexibuprofen 600/1,200 mg or racemic ibuprofen 2,400 mg daily. The primary endpoint was the improvement of the WOMAC osteoarthritis index after 15 days of therapy. The analysis was by intention to treat.The evaluation of the WOMAC OA index showed statistically significant equivalence of dexibuprofen 400 mg t.i.d. compared with racemic ibuprofen 800 mg t.i.d. by a Mann-Whitney statistic of 0.578 and the corresponding lower bound of the 95% confidence interval of 0.498. The test for superiority of dexibuprofen was borderline significant with p = 0.055. Dexibuprofen 400 mg t.i.d. and dexibuprofen 200 mg t.i.d. showed a statistically significant dose-response relationship in improving the WOMAC OA index (p = 0.023). Patients suffered from adverse drug reactions, mainly gastrointestinal disorders, 13.34% on dexibuprofen 200 mg, 15.25% on dexibuprofen 400 mg and 16.94% on racemic ibuprofen 800 mg.The active enantiomer dexibuprofen (S(+)-ibuprofen) proved to be an effective non-steroidal anti-inflammatory drug with a significant dose-response relationship in patients with painful osteoarthritis of the hip. Compared with racemic ibuprofen half of the daily dose of dexibuprofen shows at least equivalent efficacy. In contrast to pharmacokinetic data, the additional administration of R(-)-ibuprofen in form of racemate does not contribute to the clinical efficacy of racemic ibuprofen.