The objective of the study was to evaluate whether or not there is a substantial pharmacokinetic interaction between diclofenac and tramadol in a new formulation of a fixed-dose combination of diclofenac 25 milligrams (mg) and tramadol 25 mg for oral administration. The study was conducted in healthy participants of both genders.

After a screening period of about 2 weeks, 36 eligible healthy men and women were randomly allocated to receive 3 sequential treatments in the following order: * a single dose of diclofenac followed by a single dose of the fixed-dose combination of diclofenac/tramadol followed by a single dose of tramadol * a single dose of tramadol followed by a single dose of the fixed-dose combination of diclofenac/tramadol followed by a single dose of diclofenac. There were washout periods of 7 days between treatments. Sixteen blood samples were collected per participant: at pre-dose and 0.16, 0.33, 0.5, 0.75, 1, 1.5, 2, 3, 4, 6, 8, 10, 12, 24 and 36 hours after administration of each of the study drugs. The pharmacokinetic parameters and relative bioavailabilities of diclofenac and tramadol (and of the tramadol metabolite M1) were determined for the new fixed-dose combination product and were compared to the single compound reference products. Furthermore, the safety (frequency of adverse events) and tolerability of the new fixed-dose combination of diclofenac 25 mg and 25 mg tramadol in healthy men and women was assessed.