Abstracts

Rationale: As part of the Equigen study, disparate generic lamotrigine (LTG) products were selected for both arms of the study. This selection was based upon bioavailability data from ANDA applications for LTG products, and dissolution, content, and purity analysis in an independent lab of selected generic LTG products purchased on the open market.Methods: Using information on market availability of various generic LTG products, several products in the 25 mg and 100 mg tablet strengths were selected for dissolution, content uniformity (CU), and purity testing by an independent laboratory. CU was determined using the acceptance value (AV), with higher AV indicating more variability in content. Generic products A-F are 25 mg tablets. Generic products V-Z are 100 mg tablets. For 100 mg tablets, multiple lots from some manufacturers were tested. Bioavailability data from original ANDA applications were supplied by the FDA for all generic LTG products. Comparisons between bioavailability and in-vitro data were made to determine which products were above or below the mean of the branded product. These comparisons were used to determine the disparate generic products for the Equigen study.Results: Products E and V, C and X, D and Y, F and Z are from the same manufacturers. All products met USP standards for dissolution and content uniformity. See tables. Conclusions: Discrepancies between ANDA and dissolution data made selection of disparate products difficult. Differences between in-vitro measures were observed for different tablet strengths from the manufacturer for products C and X, and D and Y. Greater content variability with the 100 mg strength was seen for the branded product, products C and X, D and Y, and F and Z.