Comparative pharmacokinetic analysis of a novel sustained-release dosage form of diclofenac sodium in healthy subjects.

The pharmacokinetics and relative bioavailability of diclofenac sodium from a new sustained-release formulation (Effekton-100) and from a standard sustained-release formulation (Voltaren-Retard) were compared in 11 healthy adult male volunteers. After a single oral dose of 100 mg Effekton-100, a mean maximal plasma concentration (Cmax) of 497 +/- 120 ng/ml was obtained after 7.4 h (tmax). After an identical dose of Voltaren-Retard, a peak plasma concentration of 654 +/- 329 ng/ml was obtained after 6.4 h. Plasma levels of diclofenac were determined by a new HPLC assay which was developed as part of this study and makes possible monitoring plasma levels of diclofenac for 24 h after a single dose. The mean bioavailability of diclofenac from Effekton-100 was 0.97 +/- 0.28 relative to that of Voltaren-Retard. As the rate and the extent of absorption of diclofenac sodium was not significantly different after the administration of the two investigated formulations, it can be concluded that Effekton-100 is bioequivalent to Voltaren-Retard.