HCV polymerase (IC50 = 0.31 μM; Ki = 52.3 nM)

The prodrug IDX184 targets the liver and contains the nucleotide 2'-MeG-MP. Hepatitis C virus nucleotide polymerase is inhibited by IDX184, a liver-targeted medication [1]. In comparison to the parent nucleoside, IDX184 is a second-generation oral bioavailable nucleotide prodrug that is intended to offer enhanced anti-HCV efficacy and safety. IDX184 had the highest potency (EC50=0.3-0.45) among all modified nucleosides (2' or 4'; EC50=4-6 μM) in HCV replicon testing. It was also efficacious against viruses infected with JFH-1 (EC50=0.06-0.11 μM). Among the cell lines studied, IDX184 did not cause any toxicity (CC50>100μM) [2].

IDX184 is a nucleotide prodrug designed to enhance formation in the liver of the active triphosphate of 2'-methylguanosine (2'-MeG), a potent and specific polymerase inhibitor of the hepatitis C virus (HCV). In the present study, single ascending oral doses of 5, 10, 25, 50, 75, and 100 mg IDX184 were administered sequentially to cohorts of 8 healthy subjects, randomized 6:2, active/placebo. Plasma and urine pharmacokinetic sampling was performed over a period of 120 h after dosing. Upon absorption, IDX184 rapidly disappeared from plasma, with a mean half-life (t(1/2)) of approximately 1 h, while plasma concentrations of 2'-MeG gradually increased. Consistent with a liver-targeting approach, plasma exposure of IDX184 and 2'-MeG was low and was also dose related: the mean maximum concentrations ranged from 1.1 to 17 ng/ml for IDX184 and 1.7 to 19 ng/ml for 2'-MeG, and the respective mean total area under the curve ranged from 1.2 to 22.7 and 17.3 to 334 ng·h/ml. Mean 2'-MeG plasma concentrations 24 h after dosing were 0.6 to 3 ng/ml for the 25- to 100-mg doses. Mean 2'-MeG t(1/2) values ranged from 18 to 43 h for doses of 25 mg and above. Mean cumulative urine excretion was 0.2% and 12 to 20% of administered doses for the unchanged IDX184 and 2'-MeG, respectively. IDX184 was safe and well tolerated; no serious adverse events (SAEs), dose-dependent adverse events (AEs), or dose-limiting toxicities were observed. The incidence of AEs and laboratory abnormalities was low and was similar among subjects receiving IDX184 or a placebo. All AEs were mild to moderate and resolved at the end of study. The favorable safety and pharmacokinetic profiles support further clinical evaluation of IDX184 in HCV-infected patients [1].

In HCV-infected chimpanzees receiving 10 mg/kg/day of IDX184 as a single agent for 4 days, the viral response at the end of treatment correlated significantly with 2′-MeG exposure but not with IDX184 exposure. Trough concentrations of 2′-MeG ranging from 2 to 8 ng/ml were associated with 1 to 4 log10 reductions in HCV RNA (6, 7). In the current study, plasma concentrations of 2′-MeG remained quite sustained, i.e., still above 2 ng/ml 24 h after a single dose of 50 to 100 mg IDX184. Steady-state trough concentrations were predicted to be around 10 ng/ml after repeat once-per-day (QD) dosing (data not shown). In light of the pharmacokinetic/pharmacodynamic (PK/PD) relationship established in the chimpanzees, a dose-dependent viral response can be anticipated with IDX184 treatment in HCV-infected patients [1].

Plasma pharmacokinetics.[1]
IDX184 is a prodrug that delivers the monophosphate of the nucleoside 2′-MeG in the liver. Both the parent, IDX184, and its nucleoside metabolite, 2′-MeG, were monitored in the blood. Mean (+standard deviation [SD]) plasma concentration-time curves of IDX184 (left panel) and 2′-MeG (right panel) after administration of single doses of IDX184 escalating from 5 to 100 mg are depicted in Fig. 2. Summary pharmacokinetic parameters are presented in Table 2. Following oral administration of a single dose under fasted conditions in healthy subjects, IDX184 was rapidly absorbed, and the Tmax corresponded in most subjects to the first sampling time, with a cohort median value of 0.25 to 0.49 h regardless of the administered doses. The level of plasma exposure to IDX184 was low and proportional to administered doses, with a cohort mean Cmax and AUC0-∞ ranging from 1.12 to 17.3 ng/ml and 1.19 to 22.7 ng·h/ml, respectively, as doses escalated from 5 to 100 mg. The pharmacokinetic dose proportionality of IDX184 in the studied dose range was evaluated by regression analyses of log-transformed parameters of exposure and doses. The model estimate of the slope was close to unity for Cmax (b = 0.98; 95% CI = 0.76 to 1.21) and AUC0-∞ (b = 1.01; 95% CI = 0.85 to 1.17). The plasma kinetic profile of IDX184 exhibited a steep disposition phase, with plasma concentrations quickly falling below the limit of quantitation (0.1 ng/ml) with a short yet consistent mean t1/2 of 0.58 to 1.06 h across doses. Cohort mean CL/F and Vd/F, normalized to body weight, were 49.0 to 92.1 liters/h/kg and 67.8 to 122 liters/kg, respectively, and were independent of administered doses of IDX184.
The rapid elimination of IDX184 from plasma was accompanied by the gradual appearance of 2′-MeG. Similar to results for the parent drug, the plasma concentrations of 2′-MeG were also low and reached a maximum at a cohort median Tmax of 4.00 to 6.00 h across doses. While mean Cmax and mean C24 values of 2′-MeG increased 10-fold, from 1.74 to 18.6 ng/ml and 0.25 to 2.88 ng/ml, respectively, with doses in the 5- to 50-mg range, these parameters became less dose proportional at higher doses (Table 2). The values of slope b (95% CI) resulting from dose-proportionality analyses were 0.76 (0.60 to 0.92) for Cmax and 0.84 (0.65 to 1.03) for C24. Mean Cmax and mean C24 values of 2′-MeG with 50- to 100-mg doses of IDX184 were 14.6 to 18.6 ng/ml and 2.23 to 2.88 ng/ml, respectively. In contrast, the mean AUC0-∞ of 2′-MeG had a 20-fold increase, from 17.3 to 334 ng·h/ml, as the dose increased 20-fold, and the values were shown to be dose proportional in the studied dose range (b = 1.04; 95% CI = 0.88 to 1.19). The mean elimination t1/2 of 2′-MeG, whose estimation depends on the actual observed portion of the elimination phase (concentration > LOQ), ranged from 5.42 to 12.2 h for doses up to 10 mg and from 18.0 to 42.5 h for doses of ≥25 mg.
The cohort mean ratios of IDX184 to 2′-MeG AUC0-∞ on a molar basis were low (<4%) and remained independent of the amount of dose administered, indicating a near-complete and unsaturated biotransformation of IDX184 in the studied dose range.

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Urine excretion.[1]
The amounts of parent IDX184 and its nucleoside metabolite 2′-MeG excreted in urine were monitored during a 120-h interval after administration in all subjects. Urine IDX184 could only be measured up to 12 h postdose except for one sample, where IDX184 was observed up to 24 h. Cumulative urine excretion of IDX184, which increased with increasing doses, remained consistently low across cohorts, representing only 0.2% of administered doses (Table 3). In contrast, urine 2′-MeG was quantifiable in all fractions during the entire 120-h postdose collection period. In general, the cumulative amount of 2′-MeG excreted in urine increased as the dose was escalated (Table 3). The cumulative amount of 2′-MeG excreted in urine was higher than that of IDX184, representing, on a molar basis, 12 to 20% of administered doses. Near-maximum cumulative urine excretion of 2′-MeG was reached between 48 and 72 h, and more than half of the total amount of 2′-MeG excreted was recovered within the first 24 h. Renal clearance (CLR) was independent of the amount of dose administered and remained consistent across cohorts, with a cohort mean of 123 to 177 ml/min for IDX184 and 271 to 322 ml/min for 2′-MeG.

Safety and tolerability. [1]
Single-dose IDX184 was well tolerated. There were no SAEs or dose-limiting toxicities. The most common AE was dizziness, which occurred in 2 of 36 subjects (5.6%) exposed to IDX184 and 3 of 12 subjects (25%) exposed to a placebo. Other, less-frequent AEs observed in both placebo and active groups included dermatitis contact, dysmenorrhoea, fatigue, and headache. AEs reported were all mild or moderate in intensity and resolved by the end of the study. There were no discernible patterns in AEs between treatment groups. Laboratory parameters were stable over time for all treatment groups. No clinically meaningful changes were observed in vital sign measurements, physical examination findings, or ECG parameters.

[1]. Safety and Pharmacokinetics of IDX184, a Liver-Targeted Nucleotide Polymerase Inhibitor of Hepatitis C Virus, in Healthy Subjects. Antimicrob Agents Chemother. 2011 Jan;55(1):76-81.

[2]. IN VITRO ANTIVIRAL ACTIVITY AND PHARMACOLOGY OF IDX184, A NOVEL AND POTENT INHIBITOR OF HCV REPLICATION.

Currently, ethical concerns and technical challenges prevent direct assessment in humans of hepatic intracellular IDX184 and related phosphorylated forms of 2′-MeG. While liver biopsy specimens were not obtained in this study, the extent of conversion from IDX184 to 2′-MeG-MP and subsequent phosphates may nevertheless be approximated by the ratio of plasma exposure of parent IDX184 to 2′-MeG. Despite a 20-fold change in dose, the mean molar ratio of AUC0-∞ of IDX184 to 2′-MeG, ranging from 2.2 to 3.8%, was low and consistent across doses, suggesting a near-complete conversion which was not saturated at the highest IDX184 dose studied.
Parent IDX184 and its metabolite 2′-MeG were excreted in urine. Although no formal statistical analyses were performed, the amounts of both entities recovered in urine appeared to be dose related. Urinary excretion of IDX184 was limited, whereas cumulative urine excretion of 2′-MeG was substantial, accounting for approximately 12 to 20% of the administered dose. Renal clearance, in particular for 2′-MeG, was greater than the normal glomerular filtration rate of 80 to 120 ml/min, indicating the involvement of active components in renal elimination.
In summary, single oral doses of 5 mg to 100 mg of IDX184 were safe and well tolerated by the healthy subjects in this study. Following oral administration, plasma IDX184 and 2′-MeG concentrations were low, consistent with IDX184 being a liver-targeted prodrug. The favorable safety and pharmacokinetic profiles of IDX184 support further clinical evaluation of IDX184 in HCV-infected patients.[1]

C25H35N6O9PS

626.62

626.192

C, 47.92; H, 5.63; N, 13.41; O, 22.98; P, 4.94; S, 5.12

1036915-08-8

135565589

White to off-white solid powder

1.892

6

13

14

42

1060

4

FGHMGRXAHIXTBM-TWFJNEQDSA-N

InChI=1S/C25H35N6O9PS/c1-24(2,13-32)22(35)42-10-9-38-41(37,28-11-15-7-5-4-6-8-15)39-12-16-18(33)25(3,36)21(40-16)31-14-27-17-19(31)29-23(26)30-20(17)34/h4-8,14,16,18,21,32-33,36H,9-13H2,1-3H3,(H,28,37)(H3,26,29,30,34)/t16-,18-,21-,25-,41?/m1/s1

S-[2-[[(2R,3R,4R,5R)-5-(2-amino-6-oxo-1H-purin-9-yl)-3,4-dihydroxy-4-methyloxolan-2-yl]methoxy-(benzylamino)phosphoryl]oxyethyl] 3-hydroxy-2,2-dimethylpropanethioate

IDX-184; IDX184; 1036915-08-8; Guanosine, 2'-C-methyl-, 5'-(2-((3-hydroxy-2,2-dimethyl-1-oxopropyl)thio)ethyl N-(phenylmethyl)phosphoramidate); 4W44B4S9OC; S-[2-[[(2R,3R,4R,5R)-5-(2-amino-6-oxo-1H-purin-9-yl)-3,4-dihydroxy-4-methyloxolan-2-yl]methoxy-(benzylamino)phosphoryl]oxyethyl] 3-hydroxy-2,2-dimethylpropanethioate; UNII-4W44B4S9OC; SCHEMBL3132403; IDX 184

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

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

DMSO : ~250 mg/mL (~398.97 mM)

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.

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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).

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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)

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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).

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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

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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.

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