Intestinal Drug Transporters in Veterinary Animals

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Intestinal Drug Transporters in Veterinary Animals Intestinal transporters in the ATP Binding Cassette Family (ABC) reduce the absorption of many xenobiotics including prescription drugs. ABCG2 encodes BCRP, an important transporter that is highly expressed in the intestine as well as other barrier tissues such as the Blood Brain Barrier. BCRP limits the oral bioavailability of its substrates and therefore candidate drugs that are found to highly interact with BCRP are often discarded during drug development. Only those with limited or no interactions with BCRP are selected for further development. However, for veterinary drug development, cell lines expressing the appropriate species orthologs of BCRP are not available. Since species differences in the substrate and inhibitor selectivity of transporters are likely to occur, the lack of cell lines expressing species orthologs of transporters represents an enormous gap for veterinary drug development. The goals of this Phase I SBIR research are to create and characterize cell lines and yeast strains stably expressing veterinary animal BCRP from dog, cat, sheep and pig. The cell lines and yeast strains will serve as resources for drug developers, and will represent innovative “alternative methods, in support of replacement/reduction/refinement for activities involving animal research.” In studies under aim 1, we will create stable cell lines and yeast strains expressing the species orthologs of BCRP. In aim 2, we will create robust assays and use model substrates and inhibitors of BCRP to characterize species differences in the substrate and inhibitor specificity of the transporter. Methods used in the proposed studies include technologies for creation of cell lines stably expressing the transporter orthologs, and isotopic uptake and flux assays in cells. Yeast transformation procedures and cytotoxicity assays will also be applied. Collectively these studies will enable veterinary drug development by providing much needed cell lines for predicting drug absorption. The cell lines will reduce the reliance on trial-and-error experimental approaches in animals.