ACT-281959 (molecular weight 850.9 g/mol), the di-ester prodrug of ACT-246475 (molecular weight 618.6 g/mol), was developed to improve absorption after oral dosing and is rapidly converted by esterases in vivo to ACT-246475 in two-steps via the formation of ACT-409100 (molecular weight 734.7 g/mol), the mono-ester prodrug. ACT-281959 is a novel potent and selective P2Y12 receptor antagonist with a wider therapeutic window. ACT-281959 showed antithrombotic efficacy after oral administration in the rat ferric chloride model. ACT-281959 entered clinical studies in healthy volunteers. ACT-281959 had been in phase I clinical trials by Actelion for the treatment of thrombosis. But there is no development reported for this study recently.

MDCO 700 (formerly ABP 700) is hypnosedative and anaesthetic agent that was being developed by The Medicines Company for the induction of general anesthesia and procedural sedation. It is a positive allosteric modulator of the GABAA receptor. It is a second generation analogue of etomidate, developed to retain etomidate's beneficial haemodynamic and respiratory profile but diminishing its suppression of the adrenocortical axis. Infusions of ABP-700 showed a dose-dependent hypnotic effect, and did not cause severe hypotension, severe respiratory depression, or adrenocortical suppression. The drug development for anaesthesia has been discontinued.

CRS-3123, also known as REP-3123, is a methionyl-tRNA synthetase inhibitor potentially for the treatment of enteric infections. CRS-3123 is in Phase 1 clinical development for the treatment of Clostridium difficile Infection (CDI). CRS-3123 is a small molecule protein synthesis inhibitor that acts on the novel target methionyl-tRNA synthetase (MetRS). REP-3123 has been shown to be active in vitro against clinical isolates of C. difficile including epidemic strains such as B1/ NAP1/027; MIC values of REP-3123 for C. difficile are typically 0.5 -- 1.0 mg/l. REP-3123 is also active against a range of clinically important aerobic Gram-positive bacteria including methicillin-susceptible and -resistant Staphylococcus aureus (MIC90 values of 0.06 and 0.25 mg/l, respectively), Streptococcus pyogenes (MIC90 0.5 mg/l) and enterococci (MIC90 32 mg/l). CRS-3123 has numerous potential advantages over current CDI therapies. In addition to being highly potent against all clinical isolates of C. difficile tested, CRS-3123 has several desirable qualities for the treatment of CDI which include: Narrow spectrum for C. difficile, which may substantially reduce the disruption of normal intestinal flora compared to current therapies; Inhibition of toxin production, potentially leading to lower morbidity and mortality; Inhibition of sporulation, potentially leading to lower rates of transmission and recurrence; A novel mechanism of action, which means that its use will not compromise the utility of systemic antibiotics while maintaining activity against pre-existing resistance mechanisms.

Lumicitabine (formerly called ALS-8176), a first-in-class orally administered nucleoside analogue is being developed by Alios BioPharma for the treatment of respiratory syncytial virus infections. Lumicitabine converts to plasma-circulating ALS-8112, and then to the 5'-active nucleoside triphosphate (NTP) form within host cells. Extensive and rapid RSV reduction occurred after lumicitabine treatment (EC50 = 1.79 uM), with >99% viral inhibition at 2 h after loading dose. Clinical trials of Lumicitabine for the treatment of respiratory syncytial virus infection are ongoing.