Timapiprant sodium (OC000459 sodium) is a potent, selective, and orally bioavailable D prostanoid receptor 2 (DP2, formerly known as CRTH2) antagonist with IC50 of 13 nM. It reduces nasal and ocular symptoms in allergic subjects exposed to grass pollen, a randomised, placebo-controlled, double-blind trial. OC000459 prevents T helper 2 lymphocytes and eosinophils from being activated in a mast cell-dependent manner. With Ki values of 4nM and 3nM, OC000459, an antagonist of DP2, can stop PGD2 from binding to both human DP2 and rat recombinant DP2. Treatment with OC000459 prevented LAR and the rise in sputum eosinophils following an allergen. In asthma, OC000459 seems to reduce allergic inflammation. When compared to human recombinant DP2 (Ki=13 nM), rat recombinant DP2 (Ki=3 nM), and human native DP2 (Ki=4 nM), timapiprant sodium (OC000459 sodium) potently displaces [3H] PGD2. Timapiprant sodium (OC000459 sodium) prevents Th2 lymphocytes and eosinophils from being activated by mast cells.

Physicochemical Properties

Molecular Formula	C21H17FN2NAO2
Molecular Weight	371.360059499741
Exact Mass	370.11
Elemental Analysis	C, 68.10; H, 4.35; F, 5.13; N, 7.56; Na, 6.21; O, 8.64
CAS #	950688-14-9
Related CAS #	Timapiprant; 851723-84-7
PubChem CID	11462174
Appearance	Light yellow to yellow solid powder
LogP	4.4
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	4
Rotatable Bond Count	4
Heavy Atom Count	26
Complexity	516
Defined Atom Stereocenter Count	0
InChi Key	XKRNYIKRDAGPQZ-UHFFFAOYSA-M
InChi Code	InChI=1S/C21H17FN2O2.Na/c1-13-17(11-16-8-6-14-4-2-3-5-19(14)23-16)18-10-15(22)7-9-20(18)24(13)12-21(25)26;/h2-10H,11-12H2,1H3,(H,25,26);/q;+1/p-1
Chemical Name	2-[5-fluoro-2-methyl-3-(quinolin-2-ylmethyl)indol-1-yl]acetate
Synonyms	OC000459 sodium; OC000459; Timapiprant sodium; 950688-14-9; Timapiprant sodium (OC000459); Timapiprant (sodium); 950688-14-9 (sodium); OC-000459; OC 000459; Timapiprant; Timapiprant sodium
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture.
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

Targets	human recombinant DP2 ( Ki = 0.013 μM ); rat recombinant DP2 ( Ki = 0.003 μM ); human native DP2 ( Ki = 0.004 μM )
ln Vitro	In vitro activity: Timapiprant sodium, also known as OC000459 sodium, is toxic to human Th2 lymphocytes, inhibiting their ability to chemotaxis (IC50=0.028 μM) and produce cytokines (IC50=0.019 μM)[1]. Timapiprant sodium (OC000459 sodium) at a concentration of 1 μM prevents Th2 cells and eosinophils from activating in response to IgE/anti-IgE-activated human mast cell supernatants[1]. Timapiprant sodium (OC000459 sodium) (1 nM-1000 nM; 16 hours) inhibits the anti-apoptotic effect of PGD2 on Th2 cells with an IC50 of 0.035 uM[1].
ln Vivo	Timapiprant sodium (OC000459 sodium) (gavage; 2 mg/kg, 10 mg/kg) blocks the development of blood eosinophilia in rats caused by 13,14-dihydro-15-keto-PGD2 (DK-PGD2) ( ED50=0.04 mg/kg )[1]. Timapiprant sodium (OC000459 sodium) (gavage; 0.01 mg/kg, 0.1 mg/kg, 1.0 mg/kg) reduces the guinea pigs' airway eosinophilia in reaction to a DK-PGD2 aerosol ( ED50=0.01 mg/kg )[1].
Enzyme Assay	Effect of OC000459 on Binding of [3H]PGD2 to Human DP2.[1] OC000459 inhibited the binding of [3H]PGD2 to membranes from CHO cells transfected with human DP2 with Ki of 0.013 ± 0.002 μM (n = 13 independent experiments) as shown in Fig. 2A. OC000459 also displaced [3H]PGD2 from membranes from human Th2 lymphocytes (Ki = 0.004 ± 0.001 μM; n = 3 independent experiments), indicating that the compound was active on the native receptor as shown in Fig. 2B. OC000459 was active on rat recombinant DP2 (0.003 ± 0.001 μM; n = 5 independent experiments) but did not...
Cell Assay	Timapiprant (OC000459) (0.0001 μM-10 μM; 5 hours) inhibits human Th2 lymphocyte chemotaxis (IC50=0.028 μM) and cytokine production (IC50=0.019 μM). The activation of Th2 cells and eosinophils in response to supernatants from IgE/anti-IgE-activated human mast cells is inhibited by timapiprant (OC000459) (1 μM).
Animal Protocol	This was a two-centre, double-blind, randomised, placebo-controlled, crossover study. Eligible subjects were randomised to receive OC000459 200 mg orally twice daily or matching placebo for 16 days, in addition to inhaled salbutamol as required. The washout period was 3 weeks between treatment periods. The measurement of vital signs (heart rate and blood pressure) and FEV1 during the treatment periods are shown in table 1; these measurements were performed pre-dose on days 1, 8, 15 and 16, while exhaled nitric oxide fraction (FeNO) was performed pre-dose on days 1, 8 and 15. Pre-dose blood sampling was performed for the measurements of biochemistry and haematology at days 1, 8 and 15, with pharmacokinetics also measured on days 8 and 15. Seven subjects provided blood samples for the measurement of eosinophil shape change up to 8 h post-dose on day 8. An inhaled allergen challenge was performed on day 15 at 3 h post-dose. On day 16, a methacholine challenge was performed at 3 h post-dose, followed by induced sputum; methacholine challenge and induced sputum were therefore performed 24 h post-allergen challenge. [2] Thirty-six healthy male subjects with a history of grass pollen allergic rhinoconjunctivitis were recruited for the study. All subjects were tested for skin prick positivity to grass pollen and levels of grass pollen–reactive IgE were measured by radioallergosorbent test. After giving informed consent, subjects were randomised to receive OC000459 then placebo or placebo then OC000459. Thirty-five subjects completed both treatment periods. The study design is shown in Fig. 1. The study was a single centre, randomised, double-blind, placebo-controlled, two-way crossover trial conducted out of grass pollen season. Patients underwent screening at least 14 days prior to the first dosing to ensure they were eligible to take part in the study. There were two treatment periods, each 8 days in duration. Group A received OC000459 (200-mg bid, given as two 100-mg capsules) followed by matching placebo and Group B received placebo first followed by OC000459. Each treatment period was separated by a washout period of at least 7 days to ensure drug was no longer present at the start of the second period. In practice, the washout period was 19–23 days (20.9 ± 0.7 days, mean ± SD).[3] Dissolved in 10% DMSO/saline solution; 10 mg/kg; Oral administration Sprague-Dawley rats
References	[1]. Pharmacologic profile of OC000459, a potent, selective, and orally active D prostanoid receptor 2 antagonist that inhibits mast cell-dependent activation of T helper 2 lymphocytes and eosinophils. J Pharmacol Exp Ther. 2012. [2]. Inhibition of the asthmatic allergen challenge response by the CRTH2 antagonist OC000459. Eur Respir J. 2013 Jan;41(1):46-52. [3]. The CRTH2 antagonist OC000459 reduces nasal and ocular symptoms in allergic subjects exposed to grass pollen, a randomised, placebo-controlled, double-blind trial. Allergy. 2012 Dec;67(12):1572-9.
Additional Infomation	OC000459 is under investigation for the treatment of Severe Eosinophilic Asthma. OC000459 has been investigated for the treatment of Bronchial Asthma. D prostanoid receptor 2 (DP₂) [also known as chemoattractant receptor-homologous molecule expressed on T helper 2 (Th2) cells (CRTH2)] is selectively expressed by Th2 lymphocytes, eosinophils, and basophils and mediates recruitment and activation of these cell types in response to prostaglandin D₂ (PGD₂). (5-Fluoro-2-methyl-3-quinolin-2-ylmethylindo-1-yl)-acetic acid (OC000459) is an indole-acetic acid derivative that potently displaces [³H]PGD₂ from human recombinant DP₂ (K(i) = 0.013 μM), rat recombinant DP₂ (K(i) = 0.003 μM), and human native DP₂ (Th2 cell membranes; K(i) = 0.004 μM) but does not interfere with the ligand binding properties or functional activities of other prostanoid receptors (prostaglandin E₁₋₄ receptors, D prostanoid receptor 1, thromboxane receptor, prostacyclin receptor, and prostaglandin F receptor). OC000459 inhibited chemotaxis (IC₅₀ = 0.028 μM) of human Th2 lymphocytes and cytokine production (IC₅₀ = 0.019 μM) by human Th2 lymphocytes. OC000459 competitively antagonized eosinophil shape change responses induced by PGD₂ in both isolated human leukocytes (pK(B) = 7.9) and human whole blood (pK(B) = 7.5) but did not inhibit responses to eotaxin, 5-oxo-eicosatetraenoic acid, or complement component C5a. OC000459 also inhibited the activation of Th2 cells and eosinophils in response to supernatants from IgE/anti-IgE-activated human mast cells. OC000459 had no significant inhibitory activity on a battery of 69 receptors and 19 enzymes including cyclooxygenase 1 (COX1) and COX2. OC000459 was found to be orally bioavailable in rats and effective in inhibiting blood eosinophilia induced by 13,14-dihydro-15-keto-PGD₂ (DK-PGD₂) in this species (ED₅₀ = 0.04 mg/kg p.o.) and airway eosinophilia in response to an aerosol of DK-PGD₂ in guinea pigs (ED₅₀ = 0.01 mg/kg p.o.). These data indicate that OC000459 is a potent, selective, and orally active DP₂ antagonist that retains activity in human whole blood and inhibits mast cell-dependent activation of both human Th2 lymphocytes and eosinophils.[1]

Solubility Data

Solubility (In Vitro)

DMSO: ~100 mg/mL (~270.0 mM)

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 2.08 mg/mL (5.62 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 2.08 mg/mL (5.62 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	2.6928 mL	13.4640 mL	26.9280 mL
	5 mM	0.5386 mL	2.6928 mL	5.3856 mL
	10 mM	0.2693 mL	1.3464 mL	2.6928 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.