PF-04418948 is an orally active, potent, and selective EP2 receptor antagonist. It is used as a tool compound to study involvement of EP2 receptor in various pathologies. In combination with EP4 antagonist, PF-04418948 attenuates PGE2-induced airway microvascular leak in model of asthma, and PGE2-induced gut dismotility.

OC-459 is a highly potent and selective CRTH2 antagonist which is active on both the recombinant and native human receptor. The Atopix lead compound OC-459 is effective in improving lung function and symptoms in patients with atopic eosinophilic asthma. This group represents 40-50% of all asthmatics and the magnitude of improvement in the responder population is equivalent to high dose inhaled corticosteroids. OC-459 has also been shown to reduce both nasal and eye symptoms in allergic subjects exposed to grass pollen. Of particular interest is the ability of OC-459 to reduce the rate of respiratory infections, an effect related to reduction in Th2 immunity which has a damaging effect on host defence. OC-459 has also demonstrated an excellent safety profile in around 800 subjects exposed drug and no safety issues have been highlighted in long term toxicology. OC-459 is in Phase 2 clinical trial in patients with moderate to severe atopic dermatitis.

Icometasone (CL09) is a synthetic glucocorticoid corticosteroid. It is a metabolite of Mometasone Furoate. The binding on human serum albumin was shown to be non saturable, suggesting that other proteins were involved in CL09 binding. This binding was demonstrated to be reversible. CL09 was extensively metabolized since no unchanged CL09 was recovered in bile or urine and at least nine metabolites have been detected. It was studied in Europe as an anti-asthmatic agent but investigation is discontinued.

N6022 is a novel, first-in-class drug with potent reversible inhibitory activity against S-nitrosoglutathione reductase (GSNOR) and a potential agent for the treatment of acute asthma and cystic fibrosis (CF). Decreased levels of GSNO in the lungs of asthmatics and cystic fibrosis patients have been attributed to increased GSNO catabolism via GSNO reductase (GSNOR) leading to loss of GSNO- and NO- mediated bronchodilatory and anti-inflammatory actions. N6022 restore GSNO levels by inhibiting GSNOR. Inhibition of GSNOR by N6022 has shown safety and efficacy in animal models of asthma, chronic obstructive pulmonary disease, and inflammatory bowel disease. N6022 reduced bronchoconstriction and pulmonary inflammation in a mouse model of asthma. The significant bronchodilatory and anti-inflammatory actions of N6022 in the airways are consistent with restoration of GSNO levels through GSNOR inhibition.

AZD-1981, developed by AstraZeneca, is a potent (binding IC50 of 4nM), fully reversible, functionally non-competitive antagonist of human CRTh2. It blocks agonist-induced human eosinophil CD11b expression, shape change (including in whole blood), and chemotaxis as well as an basophil shape change and Th2-cell chemotaxis at IC50's of 8.5-50nM. Potency is similar across species as is plasma protein binding (~97%). AZD-1981 is a weak (10s of μM) inhibitor in vitro of CYP2C9, OATP1B1 and UGT1A1 as well as an inducer of CYP3A4. AZD-1981 was well tolerated and no safety concerns were identified.There was no beneficial clinical effect of AZD-1981, at a dose of 1000 mg twice daily for 4 weeks, in patients with moderate to severe COPD. AZD-1981 has being discontinued for asthma and chronic obstructive pulmonary disease. AstraZeneca is collaborating with Johns Hopkins University for the development of AZD-1981 in the treatment of chronic idiopathic urticaria. It is in phase II clinicals studies for the treatment of Urticaria.

Trichostatin A (TSA) was originally isolated as an antifungal antibiotic along with its fermentation congeners trichostatin B ((TSA)3-Fe) and the D-glucopyranosides trichostatin C and D. TSA inhibits HDAC in the low nanomolar range and is an inducer of histone hyperacetylation, both in vitro and in vivo. It inhibits all class I and II deacetylases to a similar extent in both tumor and non-tumor cells, although HDAC4 is slightly resistant when compared with HDAC1 and HDAC6. Class III HDAC is not affected by TSA. It has been shown that TSA dosedependently inhibits growth and induces apoptosis in a plethora of carcinoma cell lines in vitro. Recently, it was also found that TSA inhibits angiogenesis, which is important for the growth and metastasis of solid tumors, both in vivo and in vitro. In HT-29 colon carcinoma cells, a single dose of TSA induced transient hyperacetylation of histone H4 resulting in the induction of p21WAF1/Cip1 and inhibition of cellular proliferation at both the G1 and G2 phases of the cell cycle. Growth inhibition was associated with decreased cyclin D1 mRNA and cdk6 protein levels and increased cyclin D3 protein and p21WAF1/Cip1 mRNA levels. Cyclin D1 protein, cyclin D3 mRNA, cdk2 and cdk4 remained unaffected. In addition, TSA induced apoptosis by upregulating the expression of the pro-apoptotic genes ID1, ID2 and ID3, whereas the expression of the anti-apoptotic genes BclxL and Hsp27 was decreased In vivo, TSA induces differentiation and shows chemotherapeutic activity against N-methylnitrosureainduced rat mammary cancer without toxic side effects. TSA may also have therapeutic potential for the treatment of a variety of genetic and infectious diseases since silenced, transduced genes are reactivated probably due to structural changes of the chromatin on integrated viral sequences.

Fiboflapon sodium (GSK2190915) is a high affinity 5-lipoxygenase-activating protein inhibitor being developed for the treatment of asthma. The compound was originally developed by Amira Pharmaceuticals. Fiboflapon sodium (GSK2190915) exhibits excellent preclinical toxicology and pharmacokinetics in rat and dog. GSK2190915 also demonstrated an extended pharmacodynamic effect in a rodent bronchoalveolar lavage (BAL) model. Oral administration of Fiboflapon sodium (GSK2190915) (1 mg/kg) resulted in sustained inhibition of ex vivo ionophore-challenged whole blood LTB4 biosynthesis with >90% inhibition for up to 12 h and an EC50 of approximately 7 nM. When rat lungs were challenged in vivo with calcium-ionophore, Fiboflapon sodium inhibited LTB4 and cysteinyl leukotriene (CysLT) production with ED50s of 0.12 mg/kg and 0.37 mg/kg, respectively. Fiboflapon sodium is in Phase-II for Asthma (Adjunctive treatment) in Poland, Ukraine, Bulgaria, USA, United Kingdom and Canada (PO).

Apocynin, also known as acetovanillone, is a natural organic compound related to vanillin. It has been isolated from a variety of plant sources. Metabolites of apocynin are able to block the activity of NADPH oxidase, thus giving apocynin antioxidant and anti-inflammatory capabilities. Effects of apocynin on the concentration of reactive oxygen and nitrogen species in patients with asthma and chronic obstructive pulmonary disease were investigated in phase I clinical trials. In preclinical models, it was found that apocynin provides neuroprotective effects in models of stroke and Parkinson's disease.

Quiflapon Sodium (MK-0591; (3-[1-(4-chlorobenzyl)-3-(t-butylthio)-5-(quinolin-2-yl-methoxy)- indol-2-yl]-2,2-dimethyl propanoic acid, previously L-686,708) had been in phase II clinical studies for the treatment of inflammatory bowel disease, but the study was discontinued later, because in spite of MK-591 markedly inhibited Leukotrienes (LT) biosynthesis, it did not differ significantly from placebo in clinical efficacy. Also was discovered, that MK-0591 may modify the airway changes associated with bronchial hyper responsiveness, as well as offer symptomatic relief in asthma. MK-0591 is a selective and specific 5-Lipoxygenase-activating protein (FLAP) inhibitor with an IC50 value of 1.6 nM in a FLAP binding assay. In additional, recently was discovered, that MK591 possesses all major attributes of a standard anti-metastatic agent with significant cancer-selective effect, and suggest that MK591 may turn out to be an effective agent for therapy of castration-resistant, bone-metastatic prostate cancer. Though details of the molecular underpinnings of the anti-metastatic action of MK591 are unknown at this time, this finding gives an opportunity for further exploration to better understand the signaling mechanisms involved by in vitro and in vivo experiments.

Decloxizine (UCB-1402; NSC289116) is a histamine 1 receptor antagonist. Decloxizine is a broncholyticum.