A Two‐Way Cross‐Over Bioequivalence Study Comparing Two Products of Diclofenac Sodium Suppositories in Healthy Human Volunteers

: This report presents the results of two treatment cross‐over investigations on 20 healthy male volunteers to assess the bioequivalence of two suppository products of diclofenac sodium. The study was carried out under US Food and Drug Administration Guidelines. The two products were voltaren® (100 mg) suppository (Ciba‐Giegy), as a reference product, and Inflaban® (100 mg) suppository (The Arab Pharmaceutical Manufacturing Company, Ltd. “APM”), as a test product. Both products were administered rectally as a single dose (100 mg) separated by a one‐week wash‐out period. Following drug administration, blood samples were collected over 12 hr, and serum harvested from the blood was analyzed for diclofenac sodium using a sensitive and specific high performance liquid chromatographic assay. The results of this investigation indicated that there were no statistically significant differences between the two products in either the mean concentration‐time profiles or in the obtained pharmacokinetic parameters, including area under the serum concentration‐time curve for 12 hr (AUC0–12h), lag time between product administration and first appearance of the drug in serum (Tlag), peak serum concentration (Cmax), and time to reach this peak serum concentration (Tmax). Concerning the relative extent of absorption, assessed by the AUC ratio (Inflaban/Voltaren) for 12 hr, the average value was found to be 1.00±0.09 with a 95% confidence limits (C.L.) of 0.82–1.18. Thus, these findings clearly indicate that the two products are bioequivalent in terms of rate and extent of drug absorption.