Arbidol inhibits the cell entry of HCV pseudoparticles of genotypes 1a, 1b, and 2a in a dose-dependent fashion. Arbidol also displays a dose-dependent inhibition of HCV membrane fusion, as assayed by using HCV pseudoparticles (HCVpp) and fluorescent liposomes. Arbidol is found to present potent inhibitory activity against enveloped and non-enveloped RNA viruses, including FLU-A, RSV, HRV 14 and CVB3 when added before, during, or after viral infection, with IC50 ranging from 2.7 to 13.8 mg/mL. Arbidol shows selective antiviral activity against AdV-7, a DNA virus, only when added after infection (therapeutic index (TI) = 5.5).Arbidol induces changes to viral mRNA synthesis of the PB2, PA, NP, NA, and NS genes in MDCK cultures infected with influenza A/PR/8/34. Arbidol interacts and modifies the physicochemical properties of the phospholipids in the membrane, having a significant effect on negatively charged phospholipids but a minor one on zwitterionic phospholipids. Arbidol is located at the interface of the membrane, participates in hydrogen bonding either with water or the phospholipid or both, and decreases the hydrogen bonding network of the phospholipids giving place to a phospholipid phase similar to the dehydrated solid one.

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Arbidol showed potent inhibitory activity against enveloped and non-enveloped RNA viruses (FLU-A, RSV, HRV 14 and CVB3) when added before, during, or after viral infection, with IC50 values ranging from 2.7 to 13.8 μg/ml [2].
In drug treatment before infection assay (cells pretreated for 24 h then infected), Arbidol inhibited FLU-A with IC50 = 2.7 ± 1.0 μg/ml (TI = 25.7), RSV with IC50 = 8.7 ± 1.4 μg/ml (TI = 9.8), HRV 14 with IC50 = 13.4 ± 1.3 μg/ml (TI = 5.4), CVB3 with IC50 = 12.7 ± 0.4 μg/ml (TI = 6.7), and showed no inhibitory activity against AdV-7 (IC50 not reached) [2].
In virucidal assay (direct virus inactivation for 1 h), Arbidol showed virucidal activity against FLU-A (IC50 = 4.3 ± 0.7 μg/ml, TI = 16.1), RSV (IC50 = 10.4 ± 1.1 μg/ml, TI = 8.2), HRV 14 (IC50 = 13.8 ± 0.4 μg/ml, TI = 5.3), and CVB3 (IC50 = 13.1 ± 0.6 μg/ml, TI = 6.5), but not against AdV-7 (IC50 not reached); concentrations >8 μg/ml completely abolished FLU-A biological activity [2].
In drug treatment after infection assay (virus added first then drug), Arbidol was broadly inhibitory for all five viruses, with IC50 values: CVB3 9.5 ± 0.6 μg/ml, RSV 11.5 ± 1.2 μg/ml, FLU-A 9.6 ± 1.0 μg/ml, HRV 14 12.5 ± 1.7 μg/ml, and AdV-7 15.4 ± 0.3 μg/ml (TI = 5.5) [2].

In BALB/c mice infected with influenza A virus (A/PR/8/34 H1N1), oral administration of Arbidol at 50 or 100 mg/kg/day beginning 24 h pre-virus exposure for 6 days significantly reduced mean pulmonary virus yields and mortality rate [2].
At 100 mg/kg/day, Arbidol protected 100% of mice from death (survival rate 10/10, P<0.01), with mean day to death >21.0 ± 0.0; at 50 mg/kg/day, survival rate 70% (3/10 dead, MDD 9.4 ± 2.9, P<0.05); at 25 mg/kg/day, survival rate 50% (5/10 dead, MDD 8.6 ± 1.8, P<0.05); placebo controls had 20% survival (8/10 dead, MDD 6.4 ± 1.2) [2].
Oral Arbidol significantly decreased lung virus titers: at 100 mg/kg/day, mean virus yield 2.0 ± 0.3 Log10 TCID50/lung (P<0.01); at 50 mg/kg/day, 2.4 ± 0.2 Log10 TCID50/lung (P<0.01); at 25 mg/kg/day, 3.2 ± 0.3 Log10 TCID50/lung (P<0.01); placebo control yielded 4.9 ± 0.1 Log10 TCID50/lung [2].
Arbidol treatment prevented lung index increases: at 25, 50, and 100 mg/kg/day, lung weights were 136 ± 18 mg (P<0.05), 119 ± 8 mg (P<0.01), and 122 ± 9 mg (P<0.01), respectively, compared to placebo controls (158 ± 22 mg) [2].
Body weight loss was reduced: maximum mean weight loss at day 5 was 1.97 g (25 mg/kg/day), 1.44 g (50 mg/kg/day), and 0.7 g (100 mg/kg/day, P<0.05), versus 2.89 g in placebo controls [2].

MDCK, HEp-2, and HEL cells were seeded at 2×10^4 cells per well in 96-well plates. Serial two-fold dilutions of Arbidol in 200 μl test medium were added. At each concentration, four wells were infected with 100 TCID50/0.1 ml of virus (FLU-A, RSV, HRV 14, CVB3 or AdV-7), and four wells were left uninfected for toxicity determination. Cells were fed with Arbidol daily because its half-life in cultured cells is about 18 h. Plates were incubated at 37°C (for CVB3 and AdV-7) or 35°C (for FLU-A, RSV, HRV 14) until virus-infected untreated cells showed 80% CPE. Then 25 μl of MTT solution (5 mg/ml in PBS) was added per well, incubated for 4 h, supernatant removed, and 50 μl DMSO added to dissolve formazan crystals. Optical densities were read at 540 and 690 nm. CC50 and IC50 were determined, and therapeutic index (TI) calculated as CC50/IC50 [2].
For drug treatment before infection assay: cells were incubated with serial dilutions of Arbidol for 24 h at 37°C or 35°C, then compound removed, cells washed twice with PBS, and challenged with 100 TCID50/0.1 ml of virus for 1 h adsorption. After washing, cells were incubated with test medium until CPE visible (2 days for FLU-A, HRV 14, CVB3, AdV-7; 5 days for RSV). CPE inhibition was measured by MTT assay [2].
For virucidal assay: viral suspensions (100 TCID50/0.1 ml) were incubated with equal volume of medium with or without Arbidol for 1 h at 35°C or 37°C. Then 100 μl of mixture was added to cell monolayers, incubated for 1 h, removed, cells rinsed with PBS, and further incubated with 200 μl test medium for 2 or 5 days, then MTT assay [2].
For drug treatment after infection assay: cells were challenged with 100 TCID50/0.1 ml viruses for 1 h, washed with PBS, then overlaid with different doses of Arbidol in 200 μl test medium [2].

Female BALB/c mice (5-7 weeks old, 17-19 g) were anesthetized with ether and infected intranasally with 50 μl viral suspension containing approximately 10^5 TCID50 of influenza A virus (A/PR/8/34 H1N1). Arbidol at doses of 25, 50, or 100 mg/kg/day, ribavirin at 68 mg/kg/day, or placebo (0.5% methylcellulose solution) was orally administered three times daily (at 8-h intervals) for 6 days beginning 24 h pre-virus exposure. For survival study (n=10), mice were observed for mortality daily for 21 days after infection. For lung virus yield study (n=8), mice were sacrificed on day 5 after viral exposure; lungs were harvested, weighed, homogenized to ~10% (w/v) suspensions, frozen and thawed twice, centrifuged at 3000 rpm for 10 min, and virus titration determined by limit dilution method. Lung index was expressed as ratio of mean lung weight to mean body weight [2].
For in vivo toxicity determination: Arbidol and ribavirin were evaluated at doses of 500, 250, 125, 62.5 and 31.3 mg/kg/day by oral gavage for 6 days (n=8 per dose). Animal weights were measured prior to first treatment and 18 h after final treatment; death was observed daily for 21 days. LD50 was estimated by regression line [2].

In cultured cells, the half-life of Arbidol is about 18 h, so cells were fed with the drug daily [2].
Based on its chemical structure containing a carboxylic acid ester moiety, Arbidol may be a substrate for hydrolysis in vivo, leading to intracellular accumulation; this may explain its prophylactic activity when administered 24 h before infection [2].

Arbidol exhibited cytotoxicity against MDCK, HEL, and HEp-2 cells with CC50 values of 69.4 ± 8.5 μg/ml, 72.5 ± 3.2 μg/ml, and 85.4 ± 6.6 μg/ml, respectively. Subconfluent monolayers treated with Arbidol at 1-16 μg/ml showed no visible changes in cell morphology or cell density, whereas 32 μg/ml caused microscopically detectable alterations [2].
In vivo toxicity: oral gavage of Arbidol for 6 days gave an estimated LD50 of approximately 314 mg/kg/day; no obvious weight loss was seen at dosages below the LD50 dose. At 500 mg/kg/day, 0/8 mice survived (MDD 7.2±1.2, weight change -1.73 g); at 250 mg/kg/day, 7/8 survived (MDD 8.0±0.0, weight change -1.21 g); at 125 mg/kg/day, 8/8 survived (weight change 0.4 g) [2].

Biochemistry.2007 May 22;46(20):6050-9;Arch Virol.2007;152(8):1447-55;J Med Virol.2012 Jan;84(1):170-81.

Arbidol is an anti-influenza therapeutic that also has activity against hepatitis C virus and hepatitis B virus [2].
The mechanism of action against influenza viruses is connected to inhibition of the process of membrane fusion; enveloped viruses (FLU-A, RSV) were more sensitive to Arbidol than non-enveloped viruses in pre-treatment and virucidal assays [2].
Arbidol displayed prophylactic activity when administered 24 h before infection, indicating a possible prerequisite for intracellular accumulation [2].
In this study, Arbidol (100 mg/kg/day) demonstrated relatively greater effect than ribavirin (68 mg/kg/day, approximately one-third of LD50 dose of each) in terms of better survival rate and longer mean day to death (P<0.05) [2].
Arbidol may be a better candidate than ribavirin for treating respiratory virus infections [2].

C22H25BRN2O3S.HCL

513.88

512.053

C, 51.42; H, 5.10; Br, 15.55; Cl, 6.90; N, 5.45; O, 9.34; S, 6.24

131707-23-8

Umifenovir;131707-25-0;Umifenovir-d6 hydrochloride

9958103

White to off-white crystalline powder.

591.8ºC at 760 mmHg

133-137ºC

311.7℃

1.34E-14mmHg at 25°C

5.979

2

5

8

30

546

0

BrC1=C(C(C([H])([H])N(C([H])([H])[H])C([H])([H])[H])=C2C(C(=O)OC([H])([H])C([H])([H])[H])=C(C([H])([H])SC3C([H])=C([H])C([H])=C([H])C=3[H])N(C([H])([H])[H])C2=C1[H])O[H].Cl[H]

OMZHXQXQJGCSKN-UHFFFAOYSA-N

InChI=1S/C22H25BrN2O3S.ClH/c1-5-28-22(27)20-18(13-29-14-9-7-6-8-10-14)25(4)17-11-16(23)21(26)15(19(17)20)12-24(2)3;/h6-11,26H,5,12-13H2,1-4H3;1H

ethyl 6-bromo-4-((dimethylamino)methyl)-5-hydroxy-1-methyl-2-((phenylthio)methyl)-1H-indole-3-carboxylate hydrochloride

Umifenovir; Umifenovir HCl; Umifenovir hydrochloride; arbidol.

2934.99.9001

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, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO :25 ~ 100 mg/mL ( 48.65 ~194.59 mM )
H2O : < 0.1 mg/mL
Ethanol : ~50 mg/mL

Solubility in Formulation 1: ≥ 2.5 mg/mL (4.86 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 25.0 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.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (4.86 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 25.0 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.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (4.86 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (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 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 10% DMSO+40% PEG300+5% Tween-80+45% Saline: ≥ 2.5 mg/mL (4.86 mM)

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 (Please use freshly prepared in vivo formulations for optimal results.)