A coumarin-based prodrug strategy to improve the oral absorption of RGD peptidomimetics.

In recent years, major progress has been made in the design and synthesis of fibrinogen antagonists, which are peptidomimetic Arg-Gly-Asp (RGD) analogs. These RGD analogs are very promising antiplatelet agents. However, the clinical development of orally active RGD analogs has been hindered by the low oral bioavailability of many such RGD analogs. Aimed at enhancing their oral bioavailability, we have synthesized several coumarin-based cyclic prodrugs of RGD analogs, which have the two most polar functional groups, a carboxyl and an amino group, masked as an ester and an amide, respectively. As expected, these cyclic prodrugs have higher membrane interaction potentials as estimated by determining their partitioning between aqueous buffer and an immobilized artificial membrane than the corresponding RGD analogs. Consequently, these cyclic prodrugs are 5-6-fold more able to permeate monolayers of Caco-2 cells, an in vitro cell culture model of the intestinal mucosa barrier. Preliminary studies using dog also indicate the promising potential of using this coumarin-based prodrug strategy to improve the oral bioavailability of such RGD analogs.

Estimating intestinal mucosal permeation of compounds using Caco-2 cell monolayers.

Step-by-step protocols are provided in this unit for the measurement of apparent permeability coefficients of compounds using Caco-2 cell monolayers as an in vitro model of the intestinal mucosa. Procedures for culturing the cells and transmonolayer transport studies are also included. Critical issues for successfully estimating intestinal mucosal permeation of drugs are discussed. Step-by-step protocols are provided in this unit for the measurement of apparent permeability coefficients of compounds using.