Discovery and Development of the Novel Potent Orally Active Thrombin Inhibitor N-(9-Hydroxy-9-fluorenecarboxy)prolyl trans-4-Aminocyclohexylmethyl Amide (L-372,460):  Coapplication of Structure-Based Design and Rapid Multiple Analogue Synthesis on Solid Support

Abstract

Early studies in these laboratories of peptidomimetic structures containing a basic P1 moiety led to the highly potent and selective thrombin inhibitors 2 (Ki = 5.0 nM) and 3 (Ki = 0.1 nM). However, neither attains significant blood levels upon oral administration to rats and dogs. With the aim of improving pharmacokinetic properties via a more diverse database, we devised a resin-based route for the synthesis of analogues of these structures in which the P3 residue is replaced with a range of lipophilic carboxylic amides. Assembly proceeds from the common P2-P1 template 7 linked via an acid-labile carbamate to a polystyrene support. Application of the methodology in a repetitive fashion afforded several interesting analogues out of a collection of some 200 compounds. Among the most potent of the group, N-(9-hydroxy-9-fluorenecarboxy)-prolyl trans-4-aminocyclohexylmethyl amide (L-372,460 8, Ki = 1.5 nM), in addition to being fully efficacious in a rat model of arterial thrombosis at an infusion rate of 10 micrograms/kg/min, exhibits oral bioavailability of 74% in dogs, and oral bioavailability of 39% in monkeys with a serum half-life of just under 4 h. On the basis of its favorable biological properties, inhibitor 8 has been subject to further evaluation as a possible treatment for thrombogenic disorders.

Small, noncovalent serine protease inhibitors

“…69 The best compound out of the approximately 200 prepared in this work was the unique hydroxyfluorenyl carboxamide 27 (L-372,460). L-372,460 was efficacious in the rat ferric chloride thrombosis model and orally bioavailable in dogs and monkeys and as such was the first noncovalent inhibitor which combined good efficacy with significant oral bioavailability.…”

“…In an effort to improve the efficacy without sacrificing oral bioavailability, and using a finding from prior P3 optimization studies, 69 the less lipophilic residue D-cyclohexylglycine was incorporated in the P3 position to give essentially equipotent compound 30. 72 The potency was then enhanced by filling the previously described lipophilic region bounded by the P1 substituent, the aliphatic portion of Glu-192 and the Cys-200/Cys-191 disulfide.…”

Drug Discovery and In Silico Techniques: A Mini-Review

“…There are a number of successful examples in the literature using rational design approaches for design and discovery of NCEs [16][17][18]. The advances in computer hardware and software have made this process more effective and time efficient.…”

Pharmacokinetic properties of TDP4815 after single intravenous and oral administrations to rat, rabbit, monkey, dog and in vitro drug metabolism

“…There have been some reports of orally active thrombin inhibitors, which are efficacious in animal models of thrombosis, but the compounds need to be optimized and their oral bioavailability and pharmacokinetic properties improved [5][6][7][8][9][10][11][12].…”