L-778123 is a dual inhibitor of Farnesyl Protein Transferase (FPTase) and Geranylgeranyl Protein Transferase type-I (GGPTase-I), which can completely inhibit Ki-Ras prenylation. L-778123 has been used in phase I clinical trials to determine its effectiveness in treating patients with recurrent or refractory solid tumors. L-778123 was also studied in combination with paclitaxel to determine efficacy as a treatment for both recurrent or refractory solid tumors, and lymphomas.

R1479 (4′-azidocytidine) is a specific inhibitor of hepatitis C virus (HCV) replication. 4′-azidocytidine triphosphate is an inhibitor of native HCV replicase and recombinant HCV polymerase (NS5B). Balapiravir (R1626) is the tri-isobutyrate ester prodrug of R1479 under clinical development to improve exposure of R1479 upon oral administration.

MK-571 is a selective, orally active leukotriene D4/E4 (LTD4/E4) receptor antagonist patented by Merck Frosst Canada, Inc. for the treatment bronchoconstriction. In ex vivo models MK-571 competitively antagonizes contractions of guinea pig trachea and ileum induced by leukotriene (LT) D4 and LTE4 and contractions of human trachea induced by LTD4. MK-571 antagonizes bronchoconstriction induced in anesthetized guinea pigs by i.v. LTC4, LTD4, and LTE4 but do not block bronchoconstriction to arachidonic acid. In clinical trials, MK-571 is a potent antagonist of LTD4-induced bronchoconstriction in both normal volunteers and asthmatic patients.