Quinidine HBr is an antiarrhythmic agent. Quinidine HBr is a potent, orally bioactive, selective inhibitor of cytochrome P450db (cytochrome P450db) and an effective blocker of K+ channel, with IC50 of 19.9 μM. Quinidine HBr is also used in malaria research.

Physicochemical Properties

Molecular Formula	C20H24N2O2.HBR
Molecular Weight	405.3287
Exact Mass	404.11
CAS #	549-49-5
Related CAS #	Quinine;130-95-0;Quinine sulfate hydrate;6119-70-6;Quinine sulfate;549-56-4
PubChem CID	9822548
Appearance	Typically exists as solid at room temperature
Density	1.21g/cm3
Boiling Point	495.9ºC at 760mmHg
Melting Point	81-82ºC
Flash Point	253.7ºC
LogP	4.069
Hydrogen Bond Donor Count	2
Hydrogen Bond Acceptor Count	4
Rotatable Bond Count	4
Heavy Atom Count	25
Complexity	457
Defined Atom Stereocenter Count	4
SMILES	C=C[C@H]1CN2CC[C@H]1C[C@H]2[C@@H](C3=C4C=C(C=CC4=NC=C3)OC)O.Br
InChi Key	HDZGBIRSORQVNB-DSXUQNDKSA-N
InChi Code	InChI=1S/C20H24N2O2.BrH/c1-3-13-12-22-9-7-14(13)10-19(22)20(23)16-6-8-21-18-5-4-15(24-2)11-17(16)18;/h3-6,8,11,13-14,19-20,23H,1,7,9-10,12H2,2H3;1H/t13-,14-,19-,20+;/m0./s1
Chemical Name	(R)-[(2S,4S,5R)-5-ethenyl-1-azabicyclo[2.2.2]octan-2-yl]-(6-methoxyquinolin-4-yl)methanol;hydrobromide
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 Vitro	Quinidine hydrobromide is an antiarrhythmic medication that modifies myocardial ionic currents and has been demonstrated to be a strong blocker of various K+ channel classes in a variety of cell types [1]. Ik peak amplitude decreases in a dose-dependent manner with quinidine hydrobromide bath treatment. It is calculated that at 0 mV, the Kd for Ik blockage is 41 μM [1]. Membrane depolarization amplifies the dose-dependent rise in Ik decay rate induced by quinidine hydrobromide. Quinidine also lengthens the half-life of inactivation recovery and induces a 5 mV hyperpolarizing change in the steady-state inactivation curve. When measured at -30 mV, quinidine hydrobromide had no effect on the beginning of inactivation [1].
ln Vivo	Quinidine hydrobromide is quickly absorbed; 60 to 90 minutes after oral dosing, the plasma concentration reaches its peak. Other salts, such as polygalacturonate and gluconate, have lower peak concentrations and are absorbed more slowly [2]. About 70–90% of quinidine hydrobromide is bound to plasma proteins. In the liver, it goes through oxidative metabolism to produce N-oxide, 3-hydroxy, O-desmethyl, and 2'-quinidinone [2]. In rats, quinidine hydrobromide slows the metabolism of amphetamines. Quinidine hydrobromide pretreatment led to a large rise in amphetamine excretion to 542% between 24 and 48 hours, and a significant decrease in parahydroxyamphetamine excretion to 7.2 and 24.1% of vehicle control levels at 24 and 48 hours, respectively. command [3].
References	[1]. Quinidine-induced inhibition of the fast transient outward K+ current in rat melanotrophs. Br J Pharmacol. 1991 Jul;103(3):1807-13. [2]. Class I antiarrhythmic agents: quinidine, procainamide and N-acetylprocainamide, disopyramide.

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	2.4671 mL	12.3356 mL	24.6713 mL
	5 mM	0.4934 mL	2.4671 mL	4.9343 mL
	10 mM	0.2467 mL	1.2336 mL	2.4671 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.