Nonpeptide glycoprotein IIB/IIIA inhibitors. 12. Potent and orally active centrally constrained thieno[2,3-c]pyridones

Progress in the research of GPIIb/IIIa antagonists

This review covers the recent advances in the development of small RGD (Arg-Gly-Asp sequence) containing peptides and their mimetics as potential antithrombotic agents. Glycoprotein IIb/IIIa (GPIIb/IIIa) antagonists include monoclonal antibodies, RGD peptides, peptide hybrids and nonpeptide mimetics. The current trend in the development of nonpeptide mimetics is clearly directed toward orally active and safe antithrombotic drug candidates. But several nonpeptide mimetics, being evaluated for their oral activity in human clinical trials, are currently not approved for clinical use due to poor safety profile. It is expected that newer and more effective nonpeptide mimetics will be developed in the near future.

Orally active isoxazoline glycoprotein IIb/IIIa antagonists with extended duration of action

Modification of the alpha-carbamate substituent of isoxazoline GPIIb/IIIa (alphaIIb beta3) antagonist DMP 754 (7) led to a series of alpha-sulfonamide and alpha-sulfamide diaminopropionate isoxazolinylacetamides which were found to be potent inhibitors of in vitro platelet aggregation. Aryl- and heteroaryl-alpha-sulfonamide groups, in conjunction with (5R)-isoxazoline (2S)-diaminopropionate stereochemistry, were found to impart a pronounced duration of antiplatelet effect in dogs, potentially due to high affinity for unactivated platelets. Isoxazolylsulfonamide 34b (DMP 802), a highly selective GPIIb/IIIa antagonist, demonstrated a prolonged duration of action after iv and po dosing and high affinity for resting and activated platelets. The prolonged antiplatelet profile of DMP 802 in dogs and the high affinity of DMP 802 for human platelets may be predictive of clinical utility as a once-daily antiplatelet agent.

Synthesis and evaluation of RGD peptidomimetics aimed at surface bioderivatization of polymer substrates

Several RGD peptidomimetics have been prepared, in a convergent way, from the common ortho-aminotyrosine template (O-substituted with an anchorage-arm or a methyl group, and alpha N-substituted with a fluorine tag for XPS analysis), and various omega-aminoacid derivatives. The most flexible compounds have shown a biological activity similar to that of the peptide reference (RGDS) in the platelet aggregation test. The compound 16a could be fitted (by modelisation) with DMP 728 and c(RGDfV), two cyclic peptides that are good ligands of integrins. The compound 16b has been covalently fixed on the surface of a poly(ethylene terephthalate) membrane used as support for mammalian cell cultivation.

Non-peptide glycoprotein IIb/IIIa inhibitors. 17. Design and synthesis of orally active, long-acting non-peptide fibrinogen receptor antagonists

The synthesis and pharmacological evaluation of 5 (L-738, 167), a potent, selective non-peptide fibrinogen receptor antagonist is reported. Compound 5 inhibited the aggregation of human gel-filtered platelets with an IC50 value of 8 nM and was found to be > 33000-fold less effective at inhibiting the attachment of human endothelial cells to fibrinogen, fibronectin, and vitronectin than it was at inhibiting platelet aggregation. Ex vivo platelet aggregation was inhibited by > 85% 24 h after the oral administration of 5 to dogs at 100 micrograms/kg. The extended pharmacodynamic profile exhibited by 5 appears to be a consequence of its high-affinity binding to GPIIb/IIIa on circulating platelets and suggests that 5 is suitable for once-a-day dosing.