Nucleoside analogue; Influenza virus

Triazavirin's effectiveness against the tick-borne encephalitis virus is measured in a sensitive cell culture. Triazavirin is effective in inhibiting the reproduction of the tick-borne encephalitis virus (strain Sofiin) by accumulation in the SKEV cell culture at a concentration of 128 mcg/mL[2].

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At the frst stage, we studied the effects of Triazavirin sodium hydrate (Riamilovir) and acetylsalicylic acid on platelet aggregation in vitro. The control impedance of rabbit whole blood induced by ADP was 8.3 Ω. The reference drug in a concentration of 100 µM reduced the amplitude of platelet aggregation to 3.4 Ω, which corresponded to a signifcant inhibition of platelet functional activity relative to control by 59.8% (Table 1). Reducing acetylsalicylic acid concentration to 10 and 1 µM was followed by a decreased in the amplitude of platelet aggregation to 5.5 and 6.6 Ω, respectively. Thus, at the above concentrations, acetylsalicylic acid blocked platelet aggregation by 23.7 and 11.6%, respectively. IC50 of the reference drug was 57.5 µM. Triazavirin sodium (Riamilovir) in a concentration of 100 µM reduced the amplitude of ADP-induced platelet aggregation to 6.9 Ω, i.e. inhibited this process by 17.1% (Table 1). During incubation of the whole blood with LPS, the amplitude of platelet aggregation signifcantly increased from 8.3 to 11.9 Ω, which indicated higher activation of the platelet hemostasis in response to macrophage activation (Table 2). Antiplatelet activity of the studied drugs was evaluated in relation to the range of the difference between the level of ADP-induced aggregation of intact platelets and platelets treated with LPS. Acetylsalicylic acid in a concentration of 100 µM signifcantly reduced the amplitude of platelet aggregation to 8.91 Ω, i.e. inhibited this process by 83.2% (Table 2, Fig. 1). In concentration of 10 and 1 μM, acetylsalicylic acid reduced activity by 52.4 and 3.2%, respectively, and amplitude of platelet aggregation to 10.02 and 11.8 Ω, respectively. The IC50 value of acetylsalicylic acid was 12.4 µM (Table 2). Thus, after macrophage stimulation with LPS, activity of the reference drug increased by 4.6 times in comparison with that in intact blood.
Triazavirin sodium (Riamilovir) showed high antiplatelet activity in the presence of LPS: in a concentration of 100 µM, it inhibited platelet aggregation by 96.3% (Fig. 1) and reduced the amplitude of this process to 8.43 Ω (Table 2). When the concentration of riamilovir was reduced to 10 and 1 µM, the amplitude of platelet aggregation decreased to 9.9 and 10.9 Ω, respectively, i.e. platelet aggregation was inhibited by 56.1 and 26.8%, respectively (Fig. 1). The IC50 for riamilovir was 5.2 µM. Thus, in vitro experiments showed that under conditions of LPS stimulation of macrophages, the IC50 value for riamilovir was 2.4 times higher than for acetylsalicylic acid [4].

Triazavirin's effectiveness as a treatment against experimental Forest-Spring encephalitis in albino mice is investigated. The findings indicate that triazavirin, at high doses (200–400 mg/kg), protects the infected animals in a moderate way. Test groups' animal lifespans increased significantly (from 4.1 to 4.8 days) and there was a statistically significant drop in the amount of virus accumulation in the target organ[3].

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The second step was to fnd out whether Triazavirin sodium (Riamilovir) would have this effect in in vivo experiments. The amplitude of ADP-induced platelet aggregation in control rats was 7.9 Ω. The antiviral drug riamilovir in a dose of 20 mg/kg reduced the amplitude of platelet aggregation to 5.57 Ω, functional activity of platelets was inhibited by 29.4% (Table 3). Thus, riamilovir produced an antiplatelet effect in vivo. The amplitude of ADP-induced platelet aggregation in rats injected intravenously with LPS increased signifcantly relative to that in intact controls (to 10.9 Ω), which attested to platelet activation under the infuence of hypercytokinemia. Riamilovir reduced the amplitude of platelet aggregation to 8.98 Ω. Thus, antiplatelet activity under conditions of cytokine intoxication increased by 2.2 times in comparison with that in intact animals. [4]

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The use of Triazavirin sodium (Riamilovir) in both treatment regimens led to a reduction in the duration of inpatient treatment. The shortest periods of hospitalization were noted in patients who received the study drug at higher daily dosages. The use of riamilovir reduced the duration and severity of general infectious manifestations of the disease, while the shortest total duration of fever and a number of respiratory tract syndromes was registered among people who received riamilovir in the regimen of 1250 mg per day for 5 days, no adverse events were registered, additionally, 100% elimination of ARVI pathogens was noted in 1250 mg per day group. Conclusion: Triazavirin sodium (Riamilovir) has shown clinical efficacy and a good safety profile in in both treatment regimens. The dosage regimen of 1250 mg per day led to more significant clinical effects and to 100% elimination of ARVI pathogens in the study group by the 6th day of hospitalization[5].

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Anti-influenza activities of TZV/Triazavirin (Riamilovir) in animal models.[6]
As shown in Table 3, when administered according to the treatment-and-prophylactic scheme (24 and 1 h before infection and 24, 48, and 72 h after infection), TZV protected mice from death caused by influenza viruses of types A and B. TZV was administered by the i.g. route in the dose range of 1 to 200 mg/kg of body weight. Optimal effective doses were determined to be 50 to 100 mg/kg of body weight. As is evident from the data, TZV and rimantadine provided similar levels of protection for mice infected with a serotype A influenza virus (A/Aichi/2/68 [H3N2]), but the survival rates of animals infected with type B (B/Lee/40) and treated at about the same dosage were three to four times higher with TZV than with rimantadine. Therefore, TZV could protect 65 to 75% of mice infected with either A or B viruses. TZV was also effective when a treatment (+24 h, +48 h, and +72 h) or prophylactic (−24 h and −1 h) schemes of TZV administration were applied (data not shown). It is also noteworthy that the toxicity of TZV is low: following intraperitoneal administration to mice, the LD50 of TZV was 1,400 ± 120 mg/kg of body weight, and following i.g. administration, the LD50 was 2,200 ± 96 mg/kg of body weight. The essential characteristics of potential antiviral drugs are their stability, metabolic transformation, pharmacokinetics, and bioavailability.

This study was performed in accordance with the requirements of the current Manual for Preclinical Studies of New Pharmacological Substance. Triazavirin sodium hydrate (Riamilovir), an antiviral agent, was studied as an object of study. In in vitro experiments, the antiplatelet agent acetylsalicylic acid served as a reference drug. The choice of this medicine is based on the fact that acetylsalicylic acid is widely used as an antiplatelet agent with a high level of evidence. Triazavirin sodium hydrate (Riamilovir) was dissolved in saline; the reference drug was dissolved in 30 μl DMSO and then in saline to the required volume. The effect of the drugs on platelet aggregation was studied using Chrono-Log-700 dual-channel lumi-aggregometer using the impedance detection method. Rabbit blood for in vitro studies was sampled from the marginal ear vein by free drop method and stabilized with 3.8% sodium citrate (9:1). From the obtained sample, a constant blood volume of 450 µl was used for the study. The preparations in a concentration of 100 µM were added directly to a cuvette containing whole blood. ADP in a concentration of 5 µM was used as an inducer of platelet aggregation. In case of high antiplatelet activity, to calculate the IC50 value (concentration at which platelet aggregation is blocked by 50%), the tested samples were additionally studied in concentrations of 10 and 1 µM. Antiplatelet activity was also analyzed under conditions of hypercytokinemia. To this end, LPS solution (E. coli O111:B4) in a fnal concentration of 20 µM was added simultaneously with the test drug to a cuvette with the whole blood sample and after 5-min incubation, platelet aggregation inductor was added [4].

The efficacy of Triazavirin against the tick-borne encephalitis virus was estimated in the sensitive cell culture vs. the active drug Ribavirin. In a concentration of 128 mcg/ml Triazavirin was shown active in inhibition of the tick-borne encephalitis virus reproduction (strain Sofiin) by accumulation in the SKEV cell culture[2].

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In vitro study of antiviral activity in CAM.[6]
Chorioallantoic membranes (CAM) from 11- to 13-day-old chick embryos were minced to fragments of about 1 mm, which were suspended in Hanks' salt solution containing penicillin and streptomycin sulfate. The starting allantoic liquid containing viruses was diluted within the range of 10−1 to 10−7 and was added to wells with confluent cell monolayers. Each suspension was incubated at 37°C for 1 h, and water solutions of Triazavirin (Riamilovir)TZV at various concentrations were added to the plates. Antiviral activity was estimated by hemagglutinin titration and plaque assays after 48-h incubations at 36 to 37°C according to the method of reference 26.

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TZV/Triazavirin (Riamilovir) stability in a rabbit liver homogenate.[6]
The rabbit liver homogenate was obtained by a procedure similar to that described. The reaction mixture containing 25 mg/ml protein and 500 μM TZV was incubated at 37°C. After certain time intervals, aliquots were taken, and the reaction was terminated by the addition of cool methanol up to 66% (vol/vol). The precipitate formed was pelleted by centrifugation for 4 min at 10,000 × g. The supernatant was dried in a SpeedVac freeze dryer; the residue was dissolved in water; and the products were analyzed by HPLC as described above. The compound concentrations were calculated by peak areas.

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TZV/Triazavirin (Riamilovir) metabolism in cell cultures.[6]
A TZV water solution was added to petri dishes containing monolayers of 6 × 106 HEK 293T kidney cells or 6 × 106 Huh7 liver cells to a final concentration of 1 mM. The cell culture was incubated with the test compound for 1.5 h or 24 h. The cells were washed three times with phosphate-buffered saline (PBS), suspended in an equal volume of PBS, and broken three times by cryolysis. An equal volume of 6% trifluoroacetic acid was added to the suspension, which was then centrifuged, and the precipitate was separated. The supernatants were adjusted to a neutral pH by the addition of saturated Na2CO3 and were analyzed by HPLC as described above.

The comparative study of the therapeutic efficacy of Triazavirin against experimental Forest-Spring encephalitis on albino mice vs. the active drug Ribavirin® showed that in high doses (200-400 mg/kg) Triazavirin moderately protected the infected animals. A significant increase of the animal lifespan in the test groups (from 4.1 to 4.8 days) and a statistically (p ≤ 0.05) valid decrease of the virus accumulation in the target organ (the brain) were observed[3].

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In vivo experiments were performed on rats divided into 4 groups (6 animals per group): two groups without LPS administration (intact rats and rats intragastrically treated with Triazavirin sodium hydrate (Riamilovir)) and two groups with LPS intoxication (control animals received intravenous injection of LPS and experimental rats received LPS intravenously and riamilovir intragastrically). Riamilovir in a dose of 20 mg/kg (a dose equivalent to human dose calculated using interspecies conversion factor) was administered once intragastrically using an atraumatic gastric probe 1 h before blood sampling (the corresponding to maximum concentration in the blood). The rats were anaesthetized with chloral hydrate (400 mg/kg intraperitoneally) and the biomaterial for the study was taken from the abdominal aorta (blood stabilizer indicated above). Hypercytokinemia was modeled by intravenous injection of 2 mg/kg LPS into the caudal vein. Riamilovir was administered orally once 1 h before LPS administration, the blood was taken in 4 h after LPS administration. Controls intragastrically received an equivalent volume of distilled water. The results were processed statistically using GraphPad Prism 8.0 software (one-way ANOVA with Bonferroni correction, p<0.05). IC50, the mean and standard deviation in each group were calculated using Microsoft Excel 2020 built-in functions.[4]

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Aim: To evaluate the clinical efficacy and safety of antiviral drug Triazavirin sodium hydrate (Riamilovir) in patients with acute respiratory viral infections (ARVI) of non-coronavirus (SARS-CoV-2) etiology with different dosing regimens.
Materials and methods: The study included 150 patients with ARVI aged 18-27 years (50 patients received Triazavirin sodium hydrate (Riamilovir) in the regimen of 250 mg 3 times a day for 5 days, 50 patients received riamilovir in the off label regimen of 250 mg 5 times a day for 5 days, 50 patients received only pathogenetic treatment).[5]

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Anti-influenza activity of Triazavirin (Riamilovir)TZV in animal models. [6]
Antiviral activity in CBA mice infected with the A/Aichi/2/68 (H3N2) or B/Lee/40 influenza virus was assessed. Each group of mice included 20 animals. The virus was administered intranasally at 1 and 10 50% lethal doses (LD50) under slight ether anesthesia. A TZV water solution (0.2 ml) was administered by the intragastric (i.g.) route according to one of three schemes: the treatment-and-prophylactic scheme (24 and 1 h before infection [−24 and −1 h] and 24, 48, and 72 h after infection [+24, +48, and +72 h]), the prophylactic scheme (−24 h and −1 h), or the treatment scheme (+24 h, +48 h, and +72 h). Rimantadine was used as a control. The animals were watched for 14 days, and deaths in the control and experimental groups were reported every day. Based on these data, the degree of animal protection was calculated for TZV and compared with that of rimantadine.

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Pharmacokinetics in rabbits. [6]
For a single i.g. administration of Triazavirin (Riamilovir)/TZV to rabbits, the animals (n = 4) were anesthetized with a 10:1 ether-Fluorothane mixture, and a polyurethane gastrointestinal tube was introduced 15 cm deep. Triazavirin (Riamilovir)/TZV was administered as a water solution (12 ml) at a dose of 105 mg/kg of body weight. For i.v. administration to rabbits (n = 4), TZV (4.3 mg/kg of body weight) was injected into the vena auricularis marginalis in physiological solution (1 ml) for 1 min according to the method of reference 11. At predetermined time points up to 24 h postdosing, blood samples (1 ml on average) were collected from the vena auricularis marginalis in a self-flowing manner into microtubes containing 5 μl of heparin (5,000 U/ml). The tubes were shaken, and 0.5-ml aliquots were taken out, mixed with methanol (1 ml), and stored at −24°C. The control blood samples were taken before administration of the test compounds. Prior to HPLC analysis, the samples were centrifuged at 1,500 × g for 10 min; the supernatant was evaporated in a vacuum; and the residue was dissolved in water (100 μl). The samples were then analyzed by HPLC under the conditions described above.
Pharmacokinetic parameters were calculated using the Kinetica program. Pharmacokinetics following i.g. administration was studied by the extravascular noncompartmental model of the Thermo Kinetica program. For i.v. administration, the noncompartmental i.v. infusion model was used. The following parameters were determined: the total area under the plasma concentration-versus-time curve (AUCtot), the apparent elimination half-life (T1/2), the maximum concentration of the compound in plasma (Cmax), the time to Cmax (Tmax), and the mean residence time (MRT). The i.g. bioavailability (F) of the compound was calculated as (AUCi.g./dosei.g.)/(AUCi.v./dosei.v.), where AUCi.g. is the AUC of the compound after i.g. administration, dosei.g is the i.g. dose, AUCi.v is the AUC after i.v. administration, and dosei.v. is the i.v. dose. Total clearance (CL) from plasma was calculated as dose/AUC. The volume of distribution (Vss) of TZV at steady state was determined as CL × MRT.

TZV/Triazavirin (Riamilovir) pharmacokinetic parameters following single-dose i.v. or i.g. administration to rabbits. [6]
To determine the i.g. bioavailability of TZV, the compound was administered to rabbits (n = 4) by the i.g. and i.v. routes. At predetermined time points up to 24 h postdosing, blood samples were collected and analyzed by HPLC. For 10 min after i.g. administration, the TZV peak, with a retention time (Tret) of 22.5 min, was the only one observed in rabbit blood, whereas 2 h later, a new peak (M1) appeared, increasing with time, with a Tret of 27.5 min. The concentrations of TZV and M1 in rabbit blood within 12 h after dosing (105 mg/kg of body weight) are shown in Fig. 2A. The Cmax of TZV (1.1 mg/liter) was achieved in 0.40 ± 0.16 h, and the half-time of elimination was 1.1 h. The CL of TZV was 37.0 ± 11.2 liters/h·kg, and the Vss was 83.5 ± 19.2 liters/kg. The M1 concentration increased for 3 h and then decreased insignificantly over the next 5 h. Following i.v. administration of a 4.3-mg/kg dose of TZV to rabbits, the concentration of TZV in plasma fell quickly, with a T1/2 of 0.9 h (Fig. 2B). In contrast to the findings for i.g. administration, the metabolite M1 was not detected. The only product observed during the whole experimental time (24 h) was TZV. A summary of the values of the pharmacokinetic parameters of TZV and its metabolite is provided in Table 4. The i.g. bioavailability (F) of TZV in rabbits was calculated as 12.5%.

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Formation of the TZV/Triazavirin (Riamilovir) metabolite (M1) in a rabbit liver homogenate. [6]
Most likely the TZV metabolite was formed in the liver or kidney. To confirm this assumption, TZV was incubated with a rabbit liver homogenate. Figure 3 shows the HPLC analysis of the liver homogenate after incubation with 500 μM TZV. As can be observed, a new peak, increasing with time, was observed after 10 min of incubation. The retention time of this peak agreed well with that of the metabolite formed in rabbit blood following i.g. administration of TZV.

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TZV/Triazavirin (Riamilovir) metabolism in HEK 293T kidney and Huh7 liver cell cultures. [6]
HEK 293T or Huh7 cell cultures were incubated with 500 μM TZV for different times. HPLC analysis of cellular extracts revealed the presence of both TZV and the metabolite, whose retention time agreed with those of the M1 metabolite formed in a rabbit liver homogenate and the metabolite detected in rabbit blood following i.g. TZV administration (Fig. 4).

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TZV/Triazavirin (Riamilovir) metabolite structure. [6]
The identities of the metabolites found in cell cultures and in rabbit blood following i.g. administration and upon incubation of TZV in a rabbit liver homogenate were confirmed by comparison of retention times using data from HPLC analysis, UV spectra, and mass spectra. The patterns of UV spectra for TZV and the metabolite formed upon incubation of TZV with a rabbit liver homogenate are shown in Fig. 5. The patterns for TZV and M1 looked obviously different: TZV had two λmax, one at 257 nm and one at 360 nm, while the λmax for M1 were at 249 nm and 320 nm. We assumed that the TZV nitro group could be reduced to give 2-methylthio-6-amino-1,2,4-triazolo[5,1-c]-1,2,4-triazine-7(4H)-one (AMTZV). AMTZV was synthesized, and we showed that the UV pattern of AMTZV was identical to that of M1. For verification of the structure of the M1 metabolite formed in the liver homogenate, its mass spectrum was compared with that of the synthesized compound (Fig. 6A and B). A major ion was [M-H]−, with a molecular mass of 197, which agrees with that of AMTZV. Also, a peak of the TZV [M-H]− ion 227 was present. For ions 197 and 227, the respective satellite ions corresponding to 198 [M + 1-H]− and 199 [M + 2-H]−, as well as 228 [M + 1-H]− and 229 [M + 1-H]−, were observed. The ion structure corresponding to peak 213 is obscure. Peak 167 may relate to a metabolite degradation product, which was confirmed by mixing [M1 + AMTZV] and [M1 + 15N-AMTZV] (data not shown).

Protein Binding
Data regarding the protein binding of triazavirin is not readily available.

[1]. Preparation of chitosan-coated liposomes as a novel carrier system for the antiviral drug Triazavirin. Pharm Dev Technol. 2018 Apr;23(4):334-342.

[2]. Investigation of Triazavirin antiviral activity against tick-borne encephalitis pathogen in cell culture. Antibiot Khimioter. 2014;59(1-2):3-5.

[3]. Investigation of Therapeutic Efficacy of Triazavirin Against Experimental Forest-Spring Encephalitis on Albino Mice. Antibiot Khimioter. 2015;60(7-8):11-3.

[4]. Antiplatelet Activity of Riamilovir under Conditions of Lipopolysaccharide Intoxication. Bull Exp Biol Med. 2022 May 26;173(1):41–45.

[5]. Clinical efficiency and safety of riamilovir under various dosage regimens for treatment of acute respiratory viral infections in adults. Ter Arkh. 2023 Dec 22;95(11):930-936.

[6]. Antiviral properties, metabolism, and pharmacokinetics of a novel azolo-1,2,4-triazine-derived inhibitor of influenza A and B virus replication. Antimicrob Agents Chemother . 2010 May;54(5):2017-22.

Novel method for the coating of positively charged liposomes with modified chitosan was elaborated. Liposomes were prepared by stepwise extrusion through inorganic membranes (Anotop) of 0.2 and 0.1 μm pore sizes. Chitosan derivatives were synthesized via the Ugi multicomponent reaction. Several series of liposomal compositions were produced and their properties were compared in terms of particle size, polydispersity index (PDI), zeta potential and stability. The effect of various additives was investigated and the optimal composition of the lipid film was determined. The addition of the uncharged fatty esters allowed the diameter of the liposomes obtained by extrusion to be reduced to 145-150 nm with a PDI of 0.13-0.15. The prepared liposomes were loaded with the novel antiviral drug Triazavirin and used to determine the release profile. Triazavirin was included into liposome layer as a salt with biocompatible choline derivatives of limiting fatty acids. The appropriate lipid composition was used for the preparation of a larger quantity of liposomes coated by modified chitosan. It was shown that an appropriate combination of liposomes and polysaccharide layer potentially extended colloidal stability by up to 3 months and exhibited broad functional capabilities for surface modification. [1]

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The efficacy of Triazavirin against the tick-borne encephalitis virus was estimated in the sensitive cell culture vs. the active drug Ribavirin. In a concentration of 128 mcg/ml Triazavirin was shown active in inhibition of the tick-borne encephalitis virus reproduction (strain Sofiin) by accumulation in the SKEV cell culture.[2]

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The efficacy of Triazavirin against the tick-borne encephalitis virus was estimated in the sensitive cell culture vs. the active drug Ribavirin. In a concentration of 128 mcg/ml Triazavirin was shown active in inhibition of the tick-borne encephalitis virus reproduction (strain Sofiin) by accumulation in the SKEV cell culture. [3]

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We studied the effect of antiviral agent riamilovir on ADP-induced platelet aggregation in the absence and presence of LPS. Unlike acetylsalicylic acid (reference drug), riamilovir did not exhibit antiplatelet effect in vitro. However, it markedly suppressed platelet reactivity in LPS-treated blood samples and was 2.2-fold superior to acetylsalicylic acid in terms of IC50 value. In in vivo experiments, riamilovir under conditions of hypercytokinemia blocked platelet aggregation in rats by 64%.[4]

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Influenza viruses of types A and B cause periodic pandemics in the human population. The antiviral drugs approved to combat influenza virus infections are currently limited. We have investigated an effective novel inhibitor of human influenza A and B viruses, triazavirine [2-methylthio-6-nitro-1,2,4-triazolo[5,1-c]-1,2,4-triazine-7(4I)-one] (TZV). TZV suppressed the replication of influenza virus in cell culture and in chicken chorioallantoic membranes, and it protected mice from death caused by type A and B influenza viruses. TZV was also effective against a rimantadine-resistant influenza virus strain and against avian influenza A virus H5N1 strains. The pharmacokinetic parameters and bioavailability of TZV were calculated after the administration of TZV to rabbits. The TZV metabolite AMTZV [2-methylthio-6-amino-1,2,4-triazolo[5,1-s]-1,2,4-triazin(e)-7(4I)-one] was discovered in IAK 293T and Huh7 cell cultures, a liver homogenate, and rabbit blood after intragastric administration of TZV. AMTZV was nontoxic and inactive as an inhibitor of influenza virus in cell culture. Most likely, this metabolite is a product of TZV elimination.[6]

C₅H₇N₆NAO₅S

286.20

286.009

C, 20.98; H, 2.47; N, 29.37; Na, 8.03; O, 27.95; S, 11.20

928659-17-0

116061-59-7 (sodium);123606-06-4 (free);928659-17-0 (sodium hydrate);

52947239

Light yellow to yellow solid powder

2.0

2

10

1

18

262

0

[Na].O=C1N2C(NC(SC)=N2)=NN=C1[N+](=O)[O-].O

GDVSBVWTWGUDAW-UHFFFAOYSA-M

InChI=1S/C5H4N6O3S.Na.2H2O/c1-15-5-6-4-8-7-2(11(13)14)3(12)10(4)9-5;;;/h12H,1H3;;2*1H2/q;+1;;/p-1

sodium;7-methylsulfanyl-3-nitro-[1,2,4]triazolo[5,1-c][1,2,4]triazin-4-olate;dihydrate

Triazavirin; Riamilovir; TZV; Triazavirin; 928659-17-0; Riamilovir sodium dihydrate; Sodium 7-(methylthio)-3-nitro-4-oxo-4H-[1,2,4]triazolo[5,1-c][1,2,4]triazin-6-ide dihydrate; G1JE34QF2S; sodium;7-methylsulfanyl-3-nitro-[1,2,4]triazolo[5,1-c][1,2,4]triazin-4-olate;dihydrate; [1,2,4]Triazolo[5,1-c][1,2,4]triazin-4(6H)-one, 7-(methylthio)-3-nitro-,sodium salt, hydrate (1:1:2); (1,2,4)Triazolo(5,1-C)(1,2,4)triazin-4(6H)-one, 7-(methylthio)-3-nitro-, sodium salt, hydrate; Riamilovir sodium hydrate

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: ~125 mg/mL (~436.8 mM)
H2O: ~50 mg/mL (~174.7 mM)

Solubility in Formulation 1: ≥ 2.08 mg/mL (7.27 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.

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Solubility in Formulation 2: ≥ 2.08 mg/mL (7.27 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.

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