APD-334 (Etrasimod) was discovered as part of our internal effort to identify potent, centrally available, functional antagonists of the S1P1 receptor for use as next generation therapeutics for treating multiple sclerosis (MS) and other autoimmune diseases. APD334 is a potent functional antagonist of S1P1 and has a favorable PK/PD profile, producing robust lymphocyte lowering at relatively low plasma concentrations in several preclinical species. This new agent was efficacious in a mouse experimental autoimmune encephalomyelitis (EAE) model of MS and a rat collagen induced arthritis (CIA) model and was found to have appreciable central exposure. APD-334 has therapeutic potential in immune and inflammatory-mediated diseases such as ulcerative colitis, Crohn’s disease, and atopic dermatitis.

Tauroursodeoxycholic acid (TUDCA) is an endogenous hydrophilic bile acid used clinically to treat certain liver diseases. It is approved in Italy and Turkey for the treatment of cholesterol gallstones and is an investigational drug in China, Unites States, and Italy. Tauroursodeoxycholic acid is being investigated for use in several conditions such as Primary Biliary Cirrhosis (PBC), insulin resistance, amyloidosis, Cystic Fibrosis, Cholestasis, and Amyotrophic Lateral Sclerosis. Tauroursodeoxycholate (TUDC) promote choleresis by triggering the insertion of transport proteins for bile acids into the canalicular and basolateral membranes of hepatocytes. In addition, Tauroursodeoxycholate exerts hepatoprotective and anti-apoptotic effects, can counteract the action of toxic bile acids and reduce endoplasmic reticulum stress. Tauroursodeoxycholate can also initiate the differentiation of multipotent mesenchymal stem cells (MSC) including hepatic stellate cells and promote their development into hepatocyte-like cells. Although the hepatoprotective and choleretic action of TUDC is empirically used in clinical medicine since decades, the underlying molecular mechanisms remained largely unclear.

Sodium artesunate, an artemisinin derivative, is used in malaria treatment. Artesunate, has been licensed in Thailand for the treatment of falciparum malaria since 1990. It is a potent antimalarial drug that can reduce parasitaemia by 90% within 24 h of administration. Sodium artesunate was first isolated in China, it is a water soluble antimalaria used clinically in China.

Edaravone is a free radical scavenger developed for the treatment of amyotrophic lateral sclerosis.

Secnidazole (trade names Flagentyl, Sindose, Solosec) is a nitroimidazole derivative used to in the treatment of amoebiasis and bacterial vaginosis. Secnidazole and other 5-nitroimidazole drugs enter micro-organisms by passive diffusion and undergo activation by reduction of the 5-nitro group. In anaerobic micro-organisms, such as Trichomonas, Giardia and Entamoeba spp., this intracellular reduction occurs via the pyruvate ferredoxin oxidoreductase complex and results in a concentration gradient across the cell membrane which, in tum, enhances transport of the parent drug into the cell. Because the electron affinity of the 5-nitroimidazoles is greater than that of reduced ferredoxin, the drug interrupts the normal electron flow. Aerobic micro-organisms have a more positive redox potential (i.e. are more efficient electron acceptors) than secnidazole and other 5-nitroimidazoles, which explains the selective toxicity of these drugs against anaerobic microorganisms. DNA is the intracellular target of the Secnidazole and other 5-nitroimidazoles. Secnidazole and other 5-nitroimidazoles possess selective activity against many anaerobic Gram-positive and Gram-negative bacteria and protozoa. In general, secnidazole and metronidazole were approximately equipotent in activity against Bacteroides fragilis, Trichomonas vaginalis, and Entamoeba histolytica, in in vitro studies. Secnidazole is rapidly and completely absorbed after oral administration. Plasma drug concentrations are linear over the therapeutic dose range of 0.5 to 2g. The tolerability profile of secnidazole does not differ markedly from other 5-nitroimidazoles. The most commonly reported adverse events in clinical trials involved the gastrointestinal tract (nausea, vomiting, glossitis, anorexia, epigastric pain and a metallic taste) and occurred in 2 to 10% of patients. A headache and dizziness were experienced by about 2% of patients. The drug was equally well tolerated in adults and children, and no adverse event required therapeutic intervention or treatment withdrawal.

Uridine triacetate is used to treat an overdose of capecitabine or fluorouracil. In addition, it is used as a pyrimidine analog for uridine replacement indicated for the treatment of hereditary orotic aciduria. Following oral administration, uridine triacetate is deacetylated by nonspecific esterases present throughout the body, yielding uridine in the circulation. Uridine competitively inhibits cell damage and cell death caused by fluorouracil. Uridine can be used by essentially all cells to make uridine nucleotides, compensating for the genetic deficiency in synthesis in patients with hereditary orotic aciduria. When intracellular uridine nucleotides are restored into the normal range, overproduction of orotic acid is reduced by feedback inhibition, so that urinary excretion of orotic acid is also reduced. Adverse reactions occurring in >2% of patients receiving uridine triacetate included vomiting, nausea, and diarrhea. In vitro data showed that uridine triacetate was a weak substrate for P-glycoprotein. Due to the potential for high local (gut) concentrations of the drug after dosing, the interaction of uridine triacetate with orally administered P-gp substrate drugs cannot be ruled out.

Cholic acid is a primary bile acid synthesized from cholesterol in the liver. Endogenous bile acids including cholic acid enhance bile flow and provide the physiologic feedback inhibition of bile acid synthesis. The mechanism of action of cholic acid has not been fully established; however, it is known that cholic acid and its conjugates are endogenous ligands of the nuclear receptor, farnesoid X receptor (FXR). FXR regulates enzymes and transporters that are involved in bile acid synthesis and in the enterohepatic circulation to maintain bile acid homeostasis under normal physiologic conditions. U.S. Food and Drug Administration approved Cholbam (cholic acid) capsules, the first FDA approved treatment for pediatric and adult patients with bile acid synthesis disorders due to single enzyme defects, and for patients with peroxisomal disorders (including Zellweger spectrum disorders).

Etravirine (formerly known as TMC125) is an antiretroviral agent more specifically classified as a Non-Nucleoside Reverse Transcriptase Inhibitor. Etravirine exerts its effects via direct inhibition of the reverse transcriptase enzyme of human immunodeficiency virus type 1 (HIV-1). It directly binds reverse transcriptase and consequently blocks DNA-dependent and RNA-dependent polymerase activity. In combination with other antiretroviral agents, it is indicated for the treatment of human immunodeficiency virus type 1 (HIV-1) infection in antiretroviral treatment-experienced adult patients, who have evidence of viral replication and HIV-1 strains resistant to a non-nucleoside reverse transcriptase inhibitor (NNRTI) and other antiretroviral agents. The most common adverse events (incidence > 10%) of any intensity that occurred at a higher rate than placebo are rash and nausea. Etravirine should not be co-administered with the following antiretrovirals: Tipranavir/ritonavir, fosamprenavir/ritonavir, atazanavir/ritonavir; Protease inhibitors administered without ritonavir; NNRTIs.

Sodium oxybate is the sodium salt of gamma-hydroxybutyrate (GHB), an endogenous metabolite of gamma-aminobutyric acid (GABA) a major inhibitory neurotransmitter. Evidence suggests a role for GHB as a neuromodulator/neurotransmitter. Under endogenous conditions and concentrations, and depending on the cell group affected, GHB may increase or decrease neuronal activity by inhibiting the release of neurotransmitters that are co-localised with GHB. After exogenous administration, most of the observed behavioural effects appear to be mediated via the activity of GHB at GABA(B) receptors, as long as the concentration is sufficient to elicit binding, which does not happen at endogenous concentrations. Xyrem (sodium oxybate) oral solution is indicated for the treatment of cataplexy in narcolepsy and excessive daytime sleepiness (EDS) in narcolepsy.

Capecitabine is a fluoropyrimidine carbamate with antineoplastic activity. It is an orally administered systemic prodrug which is converted to 5-fluorouracil (5-FU). Both normal and tumor cells metabolize 5-FU to 5-fluoro-2’-deoxyuridine monophosphate (FdUMP) and 5-fluorouridine triphosphate (FUTP). These metabolites cause cell injury by two different mechanisms. First, FdUMP and the folate cofactor, N5-10-methylenetetrahydrofolate, bind to thymidylate synthase (TS) to form a covalently bound ternary complex. This binding inhibits the formation of thymidylate from 2’-deoxyuridylate. Thymidylate is the necessary precursor of thymidine triphosphate, which is essential for the synthesis of DNA, so that a deficiency of this compound can inhibit cell division. Second, nuclear transcriptional enzymes can mistakenly incorporate FUTP in place of uridine triphosphate (UTP) during the synthesis of RNA. This metabolic error can interfere with RNA processing and protein synthesis. Most common adverse reactions (≥30%) were diarrhea, hand-and-foot syndrome, nausea, vomiting, abdominal pain, fatigue/weakness, and hyperbilirubinemia. The concentration of 5-fluorouracil is increased and its toxicity may be enhanced by leucovorin.