Desmethylazelastine is the main active metabolite of Azelastine oxidatively metabolized by the cytochrome P450 enzyme system. Its protein binding rate is 97% and its elimination half-life is 54 hours. Azelastine is an orally bioactive, selective, and high-affinity histamine H1 receptor blocker (antagonist). Azelastine may be utilized in research on allergic rhinitis, asthma, diabetic hyperlipidemia, and SARS-CoV-2.

Physicochemical Properties

Molecular Formula	C21H22N3OCL
Molecular Weight	367.87188
Exact Mass	367.145
CAS #	47491-38-3
PubChem CID	162558
Appearance	Typically exists as solid at room temperature
Density	1.29g/cm3
Boiling Point	544.1ºC at 760mmHg
Flash Point	282.8ºC
Index of Refraction	1.66
LogP	4.284
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	3
Rotatable Bond Count	3
Heavy Atom Count	26
Complexity	529
Defined Atom Stereocenter Count	0
SMILES	ClC1C=CC(CC2C3C(=CC=CC=3)C(=O)N(C3CCCNCC3)N=2)=CC=1
InChi Key	WRYCMIFVXDQIKN-UHFFFAOYSA-N
InChi Code	InChI=1S/C21H22ClN3O/c22-16-9-7-15(8-10-16)14-20-18-5-1-2-6-19(18)21(26)25(24-20)17-4-3-12-23-13-11-17/h1-2,5-10,17,23H,3-4,11-14H2
Chemical Name	2-(azepan-4-yl)-4-[(4-chlorophenyl)methyl]phthalazin-1-one
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
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

ln Vivo	1.19 Pharmacokinetic characteristics of desmethylazelastine following oral guinea pigs' single 1.0 mg/kg dose of azelastine hydrochloride [1]. Blood in the lung Cmax measured in ng/mL.[a] 17.6 2863 180 28502 t1/2 (h) AUC0-24 (ng·h/mL)[a] Tmax (h) 3.0-6.0 4.0-6.0 Tlag (h) 0.25 0.39 4.24 3.90 CL (L/h) 0.213% Blood-to-lung ratio [b] 146 146 [a] The measurement for lungs is grams (g), not milliliters (mL). (b) Averaging determined across all time intervals.
References	[1]. Pharmacodynamic and pharmacokinetic studies with azelastine in the guinea pig: evidence for preferential distribution into the lung. Allergy. 1993 Jan;48(1):19-24. [2]. Management of allergic rhinitis with a combination antihistamine/anti-inflammatory agent. J Allergy Clin Immunol. 1999 Mar;103(3 Pt 2):S400-4. [3]. Craig La Force. Review of the pharmacology, clinical efficacy, and safety of azelastine hydrochloridel. Expert Rev Clin Immunol. 2005 Jul;1(2):191-201. [4]. Azelastine a potent antihistamine agent, as hypolipidemic and modulator for aortic calcification in diabetic hyperlipidemic rats model. Arch Physiol Biochem. 2020 Jul 2;1-8. [5]. Identification of SARS-CoV-2 entry inhibitors among already approved drugs. Acta Pharmacol Sin. 2020 Oct 28 : 1-7.
Additional Infomation	Desmethylazelastine is a member of phthalazines.

Solubility Data

Solubility (In Vitro)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Solubility (In Vivo)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples. Injection Formulations (e.g. IP/IV/IM/SC) Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline) *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution. Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil) Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals). Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)] *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. Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline) Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline) Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline) Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil) Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Oral Formulations Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium) Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals). Oral Formulation 3: Dissolved in PEG400 Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose Oral Formulation 6: Mixing with food powders Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	2.7184 mL	13.5918 mL	27.1835 mL
	5 mM	0.5437 mL	2.7184 mL	5.4367 mL
	10 mM	0.2718 mL	1.3592 mL	2.7184 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.