RO 4938581 (also known as Ro 4882224) is a novel, potent and selective GABAA α5 inverse agonist, with a Ki of 4.6 nM for GABAA α5β3γ2a, and shows a lower affinity at α1β3γ2a, α2β3γ2a, α3β3γ2a (Ki, 174, 185, 80 nM, respectively); RO 4938581 is used in the research of cognitive dysfunction. RO4938581 displays strong CYP1A2 autoinduction properties in rats. RO4938581 acts as a subtype-selective inverse agonist at the α5 subtype of the benzodiazepine binding site on the GABAA receptor. It has good selectivity for the α5 subtype and did not produce convulsant or anxiogenic effects in animal studies, making it a promising potential nootropic. Ro4938581 and a related derivative basmisanil (RG-1662, RO5186582) have subsequently been investigated for the alleviation of cognitive dysfunction in Down syndrome.

Physicochemical Properties

Molecular Formula	C13H8BRF2N5
Molecular Weight	352.136927604675
Exact Mass	350.993
CAS #	883093-10-5
PubChem CID	11624499
Appearance	White to off-white solid powder
Density	1.9±0.1 g/cm3
Boiling Point	559.8±60.0 °C at 760 mmHg
Flash Point	292.4±32.9 °C
Vapour Pressure	0.0±1.5 mmHg at 25°C
Index of Refraction	1.784
LogP	2.83
Hydrogen Bond Donor Count	0
Hydrogen Bond Acceptor Count	5
Rotatable Bond Count	1
Heavy Atom Count	21
Complexity	401
Defined Atom Stereocenter Count	0
InChi Key	AFJRYPJIKHMNGL-UHFFFAOYSA-N
InChi Code	InChI=1S/C13H8BrF2N5/c14-7-1-2-9-8(3-7)13-17-5-19-21(13)4-10-11(12(15)16)18-6-20(9)10/h1-3,5-6,12H,4H2
Chemical Name	15-bromo-5-(difluoromethyl)-2,4,8,9,11-pentazatetracyclo[11.4.0.02,6.08,12]heptadeca-1(13),3,5,9,11,14,16-heptaene
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	RO 4938581 is a strong and specific inverse agonist for GABAA α5; its Ki for GABAA α5β3η2a is 4.6 nM, whereas its affinity for α1β3η2a, α2β3η2a, and α3β3η2a is 174, 185, and 80 nM, respectively [1].
ln Vivo	RO 4938581 (0.3-1 mg/kg, p.o.) reverses the delayed matching place (DMTP) task's effects on working memory, scopolamine's effects on working memory, and diazepam's (RO 4938581; 1–10 mg/kg, PO) effects on spatial learning [1].
References	[1]. The discovery and unique pharmacological profile of RO4938581 and RO4882224 as potent and selective GABAA alpha5 inverse agonists for the treatment of cognitive dysfunction. Bioorg Med Chem Lett. 2009 Oct 15;19(20):5940-4.

Solubility Data

Solubility (In Vitro)

DMSO : ~100 mg/mL (~283.98 mM)

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	2.8398 mL	14.1989 mL	28.3978 mL
	5 mM	0.5680 mL	2.8398 mL	5.6796 mL
	10 mM	0.2840 mL	1.4199 mL	2.8398 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.