Bioavailability of a new effervescent tablet of diclofenac

Objective: The bioavailability of a newly developed effervescent tablet con taining 50 mg diclofenac Na (DIC-effervesc) was investigated and compared w ith an enteric-coated dragee (DIC-enteric). Subjects and method: 24 healthy , male and informed volunteers (mean body weight 78.8 kg, mean age 31.9 yea rs) received in a randomized cross-over design a single dose of 50 mg diclo fenac as DIC-effervesc and DIC-enteric. A total of 19 blood samples were ob tained before and up to 12 h after administration according to the differen t properties of the galenic formulation. Diclofenac was analyzed by a sensi tive HPLC method with a lower limit of quantification of 20 ng/ml. The bioa vailability was compared as ratios of the geometric means of AUC(0-infinity ) and C-max. Results: DIC-effervese shows no lag time, a t(max) within 30 m in and a double peak of C-max in 15/24 subjects. The mean C-max (arithm. me an I SD) for DIC-effervesc is 950 +/- 341 ng/ml (first C-max) and for DIC-e nteric 1364 +/- 335 ng/ml. The mean AUC(0-infinity) (arithm, mean +/- SD) a mounts to 1097 +/- 210 ng/mlxh for DIC-effervesc and 1262 +/- 220 ng/mlxh f or DIC-enteric. Based on the point estimator and the 90% interval DIC-effer vesc is bioequivalent in respect to amount absorbed (86.4%; 81.8 - 91.3%). DIC-effervese was well tolerated. Conclusion: The new effervescent tablet o f diclofenac Na shows a rapid absorption without lag time, the same amount of absorption and a slightly lower C-max (caused by a double peak phenomeno n) in comparison to the enteric-coated dragee. A rapid onset of therapeutic effect is postulated in acute pain disorders.