Therapeutic equivalence of diclofenac sustained-released 75 mg tablets and diclofenac enteric-coated 50 mg tablets in the treatment of painful osteoarthritis.

Efficacy and tolerability of diclofenac sustained-released (SR) 75 mg tablets taken b.i.d. were compared with that of enteric-coated diclofenac sodium 50 mg tablets given t.i.d. in a seven-day, randomised, double-blind, double-dummy, parallel groups study in 294 outpatients suffering from painful femorotibial or hip osteoarthritis. Primary efficacy criteria were spontaneous joint pain assessed on serial visual analogue scales during the first 36 hours and after 48 hours of treatment. The two treatments had equivalent efficacy since all the 90% confidence intervals of differences between means for pain intensity between the two groups were included within the interval (-10 mm; +10 mm). Rates of overall efficacy judged good to excellent ranged from 74.3-78.5% in both groups. One or more drug-related adverse events, mainly gastrointestinal, was reported by 24.5% and 27.2% of patients in diclofenac SR 75 mg and diclofenac 50 mg groups, respectively. Percentage of good compliance (i.e. > 90%) was higher with diclofenac SR 75 mg (p < 0.001).