PF-06273340 is a brain penetrant, orally available and potent tropomyosin-related kinase (Trk) inhibitor. PF-06273340 has a low metabolic turnover in Human liver microsomes and hepatocytes is a good substrate for efflux transporters P-glycoprotein and Breast cancer resistance protein (BCRP) and have moderate passive permeability. PF-06273340 was investigated in Phase I clinical trials for the treatment acute and chronic pain. However clinical development has been discontinued.

GSK-1482160 is being evaluated for treatment of inflammatory pain (such as arthritis). This compound acts on P2X7 receptors, expressed by cells of innate and adaptive immunity. P2X7 receptors are involved in the production of pro-inflammatory cytokines that are thought to be an important mediator of inflammation. By blocking P2X7 receptors, less inflammatory chemicals are released, which possibly results in less inflammatory pain. Because of its ability to target P2X7R with high selectivity and to be radiolabelled with 11C, GSK-1482160 was suggested to be a useful biomarker for neuroinflammation via positron emission tomography (PET).

DSM265 is an experimental antimalarial that selectively inhibits the parasite dihydroorotate dehydrogenase (DHODH). DSM265 is the first DHODH inhibitor to reach clinical development for treatment of malaria. DSM265 is highly selective toward DHODH of the malaria parasite Plasmodium, efficacious against both blood and liver stages of P. falciparum, and active against drug-resistant parasite isolates. The only possible DSM265-related adverse event was a moderate transient elevation in serum bilirubin.