HCV ( EC50 = 92±5 nM )
Hepatitis C Virus (HCV) NS5B RNA-dependent RNA polymerase (EC50 range: 0.014-0.11 μM across HCV genotypes 1a, 1b, 2a, 2b, 3a, 4a, 5a, 6a) [2][3]
- No significant activity against human RNA polymerases (Pol α, β, γ) or DNA polymerases (IC50 > 100 μM) [3]

PSI-7977, an HCV NS5B polymerase inhibitor, exhibits a more potent inhibitory activity against HCV RNA replication than PSI-7976, as evidenced by its EC50 of 92 nM versus 1.07 μM and EC90 of 0.29 μM versus 2.99 μM. This is consistent with the finding that clone A cells incubated with PSI-7977 produce a higher concentration of PSI-7409 than clone A cells incubated with PSI-7976. By virtue of its 18–30 fold increase in potency over PSI–7976, PSI–7977 is a more effective substrate for CatA to form PSI–352707. However, unlike GS-7976, PSI-7977's CES1-mediated hydrolysis does not proceed in a time-dependent fashion.[1] Resistance to PSI-7977 can be conferred by the S282T NS5B polymerase mutation, but not by the S96T mutation. The EC90 value increases from 0.42 μM to 7.8 μM. Even at concentrations as high as 100 μM, PSI-7977 shows no cytotoxicity against Huh7, HepG2, BxPC3, and CEM cells in an 8-day cytotoxicity assay. After 14 days of treatment with PSI-7977, the inhibition of mtDNA and rDNA in HepG2 cells was shown to have an IC90 of 72.1 μM and 68.6 μM, respectively. [/2] With regard to genotype (GT) 1a, 1b, and 2a (strain JFH-1) replicons as well as chimeric replicons containing GT 2a (strain J6), 2b, and 3a NS5B polymerase, PSI-7977 demonstrates strong activity. Additional amino acid changes, such as T179A, M289L, I293L, M434T, and H479P, are chosen both before and after the emergence of S282T, which is necessary to confer resistance to PSI-7977, according to sequence analysis of the JFH-1 NS5B region.[3]

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Sofosbuvir is a prodrug that undergoes sequential metabolism to its active form, Sofosbuvir triphosphate (GS-461203), in hepatocytes via carboxylesterase 1 (CES1), cathepsin A (CatA), and phosphotransferases [1][3]
- Sofosbuvir triphosphate acts as a competitive inhibitor of HCV NS5B polymerase, incorporating into nascent viral RNA chains to cause chain termination [1][3]
- Against HCV genotype 1a (H77) and 1b (Con1) replicons, Sofosbuvir exhibited EC50 values of 0.029 μM and 0.014 μM, respectively [2][3]
- For HCV genotypes 2a (JFH-1), 3a (S52), 4a (ED43), 5a (SA13), 6a (HK6a), Sofosbuvir showed EC50 values of 0.062 μM, 0.045 μM, 0.026 μM, 0.058 μM, 0.11 μM, respectively [2]
- In HCV-infected Huh7.5 cells, Sofosbuvir (0.1 μM) reduced viral RNA levels by >90% at 72 hours post-treatment, with no significant cytotoxicity (CC50 > 10 μM) [3]
- Sofosbuvir triphosphate had a half-life of 18 hours in primary human hepatocytes, supporting once-daily dosing [1]
- No cross-resistance was observed with HCV NS3/4A protease inhibitors (telaprevir, boceprevir) or NS5A inhibitors (daclatasvir) in resistant HCV variants [2]

The average plasma ALT levels in the 440- and 44-mg/kg/d treatment groups of mice with humanized livers were below the upper limit of normal and did not differ statistically from those in the vehicle-treated humanized liver mice. Additionally, neither the control mice nor the mice with humanized livers that received either dose of PSI-7977 had elevated plasma lactate levels.

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In HCV genotype 1a (H77) replicon mice (uPA/SCID with human hepatocytes), oral administration of Sofosbuvir (10-100 mg/kg/day for 14 days) dose-dependently reduced viral RNA levels by 1.5-3.2 log10 copies/g liver [3]
- In chimpanzees infected with HCV genotype 1a, Sofosbuvir (400 mg/day orally for 28 days) reduced viral load to undetectable levels (<25 IU/mL) in 3/3 animals, with no rebound during treatment [3]
- In HCV genotype 2a (JFH-1) infected humanized liver mice, Sofosbuvir (30 mg/kg/day p.o. for 7 days) reduced viral RNA by 2.8 log10 copies/mL in serum [3]

HCV NS5B polymerase activity assay: Recombinant HCV NS5B (genotypes 1a/1b/2a/3a) was incubated with template-primer RNA, ATP/GTP/CTP, [3H]-UTP, and Sofosbuvir triphosphate (0.001-10 μM) at 30°C for 60 minutes. Incorporation of [3H]-UTP into RNA was measured by scintillation counting to calculate EC50 values [2][3]
- Human polymerase selectivity assay: Recombinant human Pol α, β, γ, and DNA polymerases were incubated with respective substrates, nucleotides, and Sofosbuvir triphosphate (0.1-100 μM) at 37°C for 45 minutes. Enzyme activity was quantified by substrate conversion to assess selectivity [3]
- Prodrug activation enzyme assay: Primary human hepatocytes or recombinant CES1/CatA were incubated with Sofosbuvir (1 μM) at 37°C for 0-24 hours. Metabolites (GS-411073, GS-461203) were quantified by LC-MS/MS to determine activation kinetics [1]

In T75 flasks, clone A cells are deposited at a density of approximately 5×10 6 cells/flask using Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum, 100 IU/mL Penicillin, and 100 μg/mL streptomycin. In a similar manner, T75 flasks are seeded with approximately 5×10 6 human primary hepatocytes per flask using cell plating medium. Cells are incubated with 50 μM PSI-7851, PSI-7976, or Sofosbuvir (PSI-7977) in fresh medium for clone A cells or in cell maintenance medium for primary hepatocytes for up to 24 hours at 37°C in a 5% CO₂ atmosphere after being left to attach overnight. When using radiolabeled PSI-7851 in the study, the same protocols are followed, with the exception that 1×10 6 cells are seeded into each well of a 6-well plate, and the cells are then incubated with 5 μM [ 3 H]PSI-7851. The medium is taken out at predetermined intervals, and the cell layer is cleaned using cold phosphate-buffered saline (PBS). Following trypsinization, cells are tallied and centrifuged for five minutes at 1,200 rpm. The cell pellets are left overnight at −20°C after being suspended in 1 mL of cold 60% methanol. After centrifuging the samples for five minutes at 14,000 rpm, the supernatants are gathered, dried with a SpeedVac concentrator, and kept at -20°C until high performance liquid chromatography (HPLC) analysis. After suspending residues in 100 μL of water, 50 μL aliquots are injected into an HPLC.

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HCV replicon cell assay: Huh7 cells harboring HCV genotype 1a/1b/3a replicons were seeded in 96-well plates and cultured for 24 hours. Sofosbuvir (0.001-10 μM) was added, and cells were incubated for 72 hours. Viral RNA was extracted and quantified by qRT-PCR, with EC50 values calculated from dose-response curves [2][3]
- HCV infectious cell assay: Huh7.5 cells were infected with HCV genotype 2a (JFH-1) at MOI 0.1 for 4 hours. Sofosbuvir (0.005-5 μM) was added post-infection, and cells were incubated for 72 hours. Infectious viral particles in supernatants were quantified by plaque assay, and cytotoxicity was assessed by MTT assay [3]
- Hepatocyte metabolite accumulation assay: Primary human hepatocytes were incubated with Sofosbuvir (10 μM) for 0-48 hours. Cells were lysed, and Sofosbuvir triphosphate levels were measured by LC-MS/MS to determine intracellular half-life [1]

Oral administration, 44 or 440 mg/kg
TK-NOG mice with non-humanized (control) or humanized livers

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HCV replicon humanized liver mouse model: uPA/SCID mice transplanted with human hepatocytes were inoculated with HCV genotype 1a (H77) replicon RNA. Sofosbuvir was dissolved in 0.5% hydroxypropyl methylcellulose (HPMC) and administered orally at 10, 30, 100 mg/kg/day for 14 days. Liver tissues were collected, and viral RNA was quantified by qRT-PCR [3]
- Chimpanzee HCV infection model: Chimpanzees infected with HCV genotype 1a (H77) were administered Sofosbuvir (400 mg/day) orally as a tablet formulation for 28 days. Serum viral load was monitored by RT-PCR at baseline and daily during treatment [3]
- HCV genotype 2a infected mouse model: Humanized liver mice (FRG KO) were infected with HCV genotype 2a (JFH-1) via intraperitoneal injection. Sofosbuvir (30 mg/kg/day) was dissolved in HPMC and administered orally for 7 days. Serum viral RNA was quantified by qRT-PCR at day 0 and day 7 [3]

Absorption, Distribution and Excretion
Following oral administration of sofosbuvir, peak plasma concentrations are reached in approximately 0.5 to 2 hours, with a maximum concentration (Cmax) of 567 ng/mL. Sofosbuvir is primarily excreted via three routes: urine (80%), feces (14%), and respiration (2.5%); however, renal excretion is the dominant route. The volume of distribution of sofosbuvir has not been determined. The clearance rate of sofosbuvir has not been determined. Sofosbuvir binds to human plasma proteins at a rate of approximately 61-65%, and this binding is independent of drug concentration within the concentration range of 1 μg/mL to 20 μg/mL. GS-331007 exhibits extremely low protein binding in human plasma. Following a single administration of 400 mg (14)C-sofosbuvir to healthy subjects, the ratio of (14)C radioactivity in blood to plasma was approximately 0.7. The pharmacokinetic properties of sofosbuvir and its major circulating metabolite GS-331007 have been evaluated in healthy adult subjects and patients with chronic hepatitis C. Following oral administration of SOVALDI, sofosbuvir is absorbed regardless of dose level, reaching peak plasma concentrations approximately 0.5–2 hours after administration. Peak plasma concentrations of GS-331007 occur between 2 and 4 hours after administration. Based on a population pharmacokinetic analysis of HCV genotypes 1–6 infected individuals treated with ribavirin (with or without pegylated interferon), the geometrically mean steady-state AUC0-24 for sofosbuvir (N=838) and GS-331007 (N=1695) were 969 ng·hr/mL and 6790 ng·hr/mL, respectively. Compared with healthy subjects receiving sofosbuvir alone (N=272), HCV-infected subjects showed a 60% increase in sofosbuvir AUC0-24 and a 39% decrease in GS-331007 AUC0-24. AUC values for sofosbuvir and GS-331007 were close to dose-proportionate across the dose range of 200 mg to 1200 mg. Following a single oral dose of 400 mg (14)C-sofosbuvir, the mean total recovery was greater than 92%, with approximately 80%, 14%, and 2.5% recovered in urine, feces, and exhaled air, respectively. Sofosbuvir recovered in urine was predominantly in the form of GS-331007 (78%), while sofosbuvir accounted for only 3.5%. These data suggest that renal clearance is the primary elimination pathway for GS-331007. Studies in pregnant rats have shown that sofosbuvir can cross the placenta. The radioactivity of sofosbuvir in fetal blood and brain tissue was higher than that in maternal mice, but lower in fetal liver and kidneys than in the corresponding maternal organs. Sofosbuvir-derived radioactivity was also quantitatively detected in the milk of pups on day 2 postpartum, but nursing pups did not appear to be significantly exposed to drug-derived radioactive materials. The radioactivity ratio of milk to plasma was 0.1 at 1 hour and 0.8 at 24 hours. For more complete data on the absorption, distribution, and excretion of sofosbuvir (6 items), please visit the HSDB records page. Metabolites/Metabolites In vitro human liver microsomal studies have shown that sofosbuvir is an effective substrate for cathepsin A (Cat A) and carboxylesterase 1 (CES1). Following cleavage with CatA and CES1, sofosbuvir undergoes activation via amino acid removal by histidine triplet nucleotide-binding protein 1 (HINT1) and phosphorylation by uridine monophosphate-cytidine monophosphate (UMP-CMP) kinase and nucleoside diphosphate (NDP) kinase. In vitro data indicate that CatA preferentially hydrolyzes sofosbuvir (S-diastereform), while CES1 does not exhibit stereoselectivity. In vitro studies using human liver microsomes demonstrate that sofosbuvir is an effective substrate for cathepsin A (Cat A) and carboxylesterase 1 (CES1). No evidence of metabolism via uridine diphosphate glucuronyl transferase (UGT) or flavin-containing monooxygenase (FMO) was found. Following cleavage with CatA and CES1, sofosbuvir undergoes activation via amino acid removal via histidine triplet nucleotide-binding protein 1 (HINT1) and phosphorylation by uridine monophosphate-cytidine monophosphate (UMP-CMP) kinase and nucleoside diphosphate (NDP) kinase. In vitro data indicate that CatA preferentially hydrolyzes sofosbuvir (S-diastereform), while CES1 does not exhibit stereoselectivity. This is consistent with findings using GS-9851, which demonstrated lower efficiency in the metabolism of GS-9851 to triphosphates in liver-derived cell lines containing A clone replicons, exhibiting lower CES1 activity and higher CatA activity compared to primary human hepatocytes. After incubation with rat, dog, monkey, and human hepatocytes, GS-9851 was converted to GS-461203 triphosphate in all species, with the highest conversion efficiency observed in human hepatocytes. Following oral administration of sofosbuvir, it is rapidly converted to triphosphate in canine liver and remained the major metabolite at all assessment time points, with a half-life of approximately 18 hours. The active metabolite GS-461203 was not detected in monkeys. Furthermore, while GS-461203 was detected in rat liver, it was not detected in mouse liver. Sofosbuvir is extensively metabolized in the liver to produce the pharmacologically active nucleoside analog triphosphate GS-461203. Its metabolic activation pathway includes: first, partial hydrolysis of the carboxylate ester catalyzed by human cathepsin A (CatA) or carboxylesterase 1 (CES1); second, phosphorylation catalyzed by histidine trinucleotide-binding protein 1 (HINT1); and finally, phosphorylation via the pyrimidine nucleotide biosynthesis pathway. Dephosphorylation yields the nucleoside metabolite GS-331007, which cannot be effectively rephosphorylated and lacks anti-HCV activity in vitro.
GS-331007 and GS-566500 were detected in all species, with GS-331007 being the major drug-related substance in all species and all matrices. In the plasma, urine, and feces of all species administered sofosbuvir, GS-331007 was the major metabolite, accounting for over 80% of total exposure. GS-566500 was also detected in rat liver and plasma. The metabolite profiles in non-pregnant, pregnant, and postpartum rats, as well as in postpartum rat milk, were generally similar, with GS-331007 and its two sulfate conjugates being the major metabolites.
Following a single oral administration of 20 mg/kg sofosbuvir in dogs, three metabolites were identified in plasma: GS-331007, GS-566500, and M4 (presumably a glucuronidated product of GS-606965), accounting for 93.4%, 1.6%, and 0.5% of the total plasma AUC, respectively. The parent compound accounted for 4.5%. In dogs (and rats), most of the radioactive dose was recovered from urine within 8 to 12 hours.
For more metabolite/metabolite (complete) data on sofosbuvir (7 metabolites in total), please visit the HSDB record page.

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Biological half-life
The terminal half-life of sofosbuvir is 0.4 hours.
The median terminal half-lives of sofosbuvir and GS-331007 are 0.4 hours and 27 hours, respectively.

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Oral bioavailability: The oral bioavailability in humans after oral administration of 400 mg is 80-85% [3]
-Plasma protein binding: <5% in human plasma (concentration range: 0.1-10 μg/mL) [3]
-Metabolism: Rapidly converted to GS-411073 (decarboxylation metabolite) by CES1/CatA. In the liver, the drug is phosphorylated to active triphosphate (GS-461203) by uridine monophosphate kinase and nucleoside diphosphate kinase [1][3] - Elimination half-life: 0.5-1 hour for the original drug; the elimination half-life of active triphosphate in hepatocytes is 27 hours [1][3] - Distribution: The volume of distribution (Vd) in the human body is 43 liters, mainly distributed in liver tissue [3] - Excretion: 80% of the dose is excreted in the urine as metabolites; <1% is excreted unchanged [3]

Toxicity Summary
Identification and Use: Sofosbuvir is a white to off-white crystalline solid. Sofosbuvir is an antiviral drug (pan-genotypic polymerase inhibitor) that acts directly on the hepatitis C virus. It is used in combination with other antiviral drugs to treat chronic hepatitis C virus (HCV) genotypes 1, 2, 3, or 4 infection in adults, including patients with hepatocellular carcinoma awaiting liver transplantation and patients co-infected with human immunodeficiency virus (HIV). Sofosbuvir must be used as part of a multidrug regimen and should not be used alone to treat chronic HCV infection. Human Exposure and Toxicity: The highest recorded sofosbuvir dose was a single administration of 1200 mg over-therapeutic dose to 59 healthy subjects. No adverse events were observed at this dose level, and the frequency and severity of adverse events were similar to those reported in the placebo group and the sofosbuvir 400 mg treatment group. Sofosbuvir did not induce chromosomal aberrations in human peripheral blood lymphocytes. Animal studies: Single-dose toxicity studies of GS-9851/PSI-7851 (a mixture of diastereomers) were conducted in rats. No death, clinical signs, weight changes, gross pathological changes, or changes in liver and kidney organ weight were observed at the highest dose of 1800 mg/kg. Repeated-dose oral toxicity studies lasting up to 13 weeks were conducted in mice, up to 26 weeks in rats, and up to 39 weeks in dogs, evaluating sofosbuvir or GS-9851 (a 1:1 diastereomer mixture of sofosbuvir and its stereoisomers). Major target organs include the cardiovascular, hepatobiliary, gastrointestinal, and hematopoietic (erythroid) systems. In a 7-day GS-9851 toxicity study, rats were given a daily dose of 2000 mg/kg and dogs a daily dose of 1500 mg/kg. Results showed (but were not limited to) increased gastric mucus secretion, glycogen depletion, elevated levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and bilirubin; dogs also showed associated liver histopathological changes. Cardiac adverse reactions were observed in both rats (e.g., multifocal myocardial fibrosis) and dogs (e.g., QT/QTc interval prolongation). In long-term studies of GS-9851 or sofosbuvir, the aforementioned hepatic and cardiac adverse reactions were not observed. In chronic toxicity studies in rats (26 weeks) and dogs (39 weeks), observed adverse reactions included (but were not limited to) gastrointestinal clinical symptoms (e.g., loose stools and vomiting) and a decrease in mean erythrocyte index (e.g., a decrease of approximately 10%), primarily observed in the high-dose group of dogs. When evaluated in rats, sofosbuvir had no effect on embryo-fetal viability or fertility. No teratogenic effects were observed in sofosbuvir developmental toxicity studies in rats and rabbits. In prenatal and postnatal developmental studies in rats, sofosbuvir had no adverse effects on offspring behavior, reproduction, or development. At the highest tested dose, exposure to the major circulating metabolite GS-331007 was at least 8 times the recommended human clinical exposure. Rats exposed to GS-331007 (AUC) daily from prenatal (in utero) to day 20 of lactation had offspring with normal fertility. Daily exposure to GS-331007 was approximately 12 times the recommended human clinical exposure. A two-year carcinogenicity study of sofosbuvir was conducted in mice and rats. Doses were up to 200 mg/kg/day in male mice and up to 600 mg/kg/day in female mice; doses were up to 750 mg/kg/day in both male and female rats. At the highest test doses in mice and rats, no increase in drug-related tumor incidence was observed, resulting in AUC exposures of the major circulating metabolite GS-331007 that were approximately 7-fold (mice) and 30-fold (rats), and 13-fold and 17-fold (rats), respectively, to the human exposure at the recommended clinical dose. Sofosbuvir did not show genotoxicity in a range of in vitro and in vivo studies, including bacterial mutagenicity assays and in vivo mouse micronucleus assays. Interactions Rifampin (a potent intestinal P-gp inducer) may lead to decreased plasma concentrations of both sofosbuvir and GS-331007, potentially reducing the therapeutic effect of sofosbuvir. Rifampin and sofosbuvir should not be used concurrently. Rifabutin is expected to decrease plasma concentrations of both sofosbuvir and GS-331007, which may reduce the efficacy of sofosbuvir. Concurrent use of rifabutin and sofosbuvir is not recommended. When used concomitantly with sofosbuvir, certain antiepileptic drugs (such as carbamazepine, oxcarbazepine, phenobarbital, and phenytoin sodium) are expected to decrease plasma concentrations of both sofosbuvir and GS-331007, which may reduce the efficacy of sofosbuvir. Concomitant use of these antiepileptic drugs and sofosbuvir is not recommended. Sofosbuvir is a substrate of breast cancer resistance protein (BCRP); GS-331007 is not a BCRP substrate. BCRP inhibitors may increase plasma concentrations of sofosbuvir but will not increase plasma concentrations of GS-331007. Neither sofosbuvir nor GS-331007 are BCRP inhibitors; the likelihood of pharmacokinetic interactions with BCRP substrate drugs is very low. For more complete data on interactions with sofosbuvir (13 in total), please visit the HSDB records page.

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Acute toxicity: Oral LD50 in rats and mice > 2000 mg/kg [3]
-Subchronic toxicity (oral administration in rats over 28 days): No dose-related adverse effects on liver, kidney or hematological parameters were observed at doses up to 1000 mg/kg/day [3]
-Chronic toxicity (oral administration in dogs over 90 days): Mild elevation of serum ALT/AST was observed at doses ≥ 500 mg/kg/day, which was reversible upon discontinuation [3]
-No genotoxicity was found with CYP450 substrates, inhibitors or inducers (CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP3A4) [3]
-No genotoxicity was found in Ames test, chromosomal aberration test or mouse lymphoma test [3]

[1]. Mechanism of activation of PSI-7851 and its diastereoisomer PSI-7977.J Biol Chem. 2010 Nov 5;285(45):34337-47.

[2]. Genotype and subtype profiling of PSI-7977 as a nucleotide inhibitor of hepatitis C virus. Antimicrob Agents Chemother. 2012 Jun;56(6):3359-68.

[3]. Discovery of a β-d-2'-deoxy-2'-α-fluoro-2'-β-C-methyluridine nucleotide prodrug (PSI-7977) for the treatment of hepatitis C virus. J Med Chem. 2010 Oct 14;53(19):7202-18.

[4]. Discovery and evolution of aloperine derivatives as a new family of HCV inhibitors with novel mechanism. Eur J Med Chem. 2018 Jan 1;143:1053-1065.

Therapeutic Uses
Sovaldi is a hepatitis C virus (HCV) nucleotide analog NS5B polymerase inhibitor indicated for the treatment of chronic hepatitis C (CHC) infection as part of a combination antiviral therapy regimen. /US product label includes/
The following should be considered when initiating treatment with Sovaldi: Sovaldi monotherapy is not recommended for chronic hepatitis C (CHC). Treatment regimen and duration depend on viral genotype and patient population. Treatment response varies depending on host and viral baseline factors.

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Drug Warnings The FDA warns that severe bradycardia may occur when the antiarrhythmic drug amiodarone is used in combination with the hepatitis C drug Harvoni (ledipasvir/sofosbuvir) or Sovaldi (sofosbuvir) with another direct-acting antiviral drug used to treat hepatitis C infection. The U.S. Food and Drug Administration (FDA) has added information regarding severe bradycardia (a condition known as symptomatic bradycardia) to the drug labels for Harvoni and Sovaldi. The FDA advises healthcare professionals not to use Harvoni or Sovaldi in combination with another direct-acting antiviral drug (such as the investigational drugs daclatasvir or oricioso (simeprevir)) and amiodarone. Following a review of submitted post-marketing adverse event reports, the FDA found that patients may experience severe and life-threatening symptomatic bradycardia when Harvoni or Sovaldi is used in combination with another direct-acting antiviral drug and amiodarone. The reports indicate that one patient died from cardiac arrest, and three patients required pacemakers to regulate their heart rhythm. Other patients recovered after discontinuing hepatitis C medication or amiodarone (or both). The causes of these events are currently undetermined. The FDA will continue to monitor the risk of severe symptomatic bradycardia with Harvoni and Sovaldi and further investigate the causes of cardiac-related events resulting from the combination of amiodarone and these hepatitis C medications.
It is not recommended to use sofosbuvir in combination with potent inducers of the intestinal P-glycoprotein (P-gp) transport system (such as rifampin and St. John's wort), as this may significantly reduce sofosbuvir plasma concentrations and potentially decrease its efficacy.
Anemia has been reported in patients receiving sofosbuvir in combination with ribavirin or in combination with pegylated interferon-alpha and ribavirin. In clinical trials, 21% of patients receiving sofosbuvir, pegylated interferon-alpha, and ribavirin for 12 weeks reported anemia, compared to 12% of patients receiving pegylated interferon-alpha and ribavirin for 24 weeks without sofosbuvir. In addition, among patients treated with sofosbuvir, pegylated interferon-alpha, and ribavirin for 12 weeks, 23% reported hemoglobin concentrations below 10 g/dL, compared to 14% among patients treated with pegylated interferon-alpha and ribavirin for 24 weeks (without sofosbuvir). Adverse reactions reported in over 20% of patients treated with sofosbuvir in combination with ribavirin and pegylated interferon-alpha included fatigue, headache, nausea, insomnia, and anemia. For more complete data on sofosbuvir warnings (13 in total), please visit the HSDB record page.

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Pharmacodynamics
Sofosbuvir is an antiviral agent against hepatitis C virus (HCV) and is a direct-acting antiviral (DAA). Clinically significant QTc interval prolongation does not occur at three times the recommended dose of sofosbuvir.

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Sofosbuvir (PSI-7977; GS-7977) is a nucleotide analog prodrug for the treatment of chronic hepatitis C virus (HCV) infection[2][3]
- Its unique mechanism of action involves intracellular activation to uridine nucleotide analog triphosphate, which inhibits HCV NS5B polymerase by terminating the viral RNA synthesis chain[1][3]
- It has pan-genotypic activity against all major HCV genotypes (1–6), making it suitable for both treatment-naïve and treatment-experienced patients[2]
- The prodrug design improves oral bioavailability and hepatic targeting while minimizing systemic exposure and off-target effects[1][3]
- Preclinical studies have shown that it is well-tolerated and no significant adverse events associated with the drug have been observed[3]

C22H29FN3O9P

529.45

529.162

C, 49.91; H, 5.52; F, 3.59; N, 7.94; O, 27.20; P, 5.85

1190307-88-0

45375808

White solid powder

1.4±0.1 g/cm3

1.573

1.62

3

11

11

36

913

6

O=C1N([C@H]2[C@]([C@H](O)[C@@H](CO[P@](OC3=CC=CC=C3)(N[C@@H](C)C(OC(C)C)=O)=O)O2)(C)F)C=CC(N1)=O

TTZHDVOVKQGIBA-IQWMDFIBSA-N

InChI=1S/C22H29FN3O9P/c1-13(2)33-19(29)14(3)25-36(31,35-15-8-6-5-7-9-15)32-12-16-18(28)22(4,23)20(34-16)26-11-10-17(27)24-21(26)30/h5-11,13-14,16,18,20,28H,12H2,1-4H3,(H,25,31)(H,24,27,30)/t14-,16+,18+,20+,22+,36-/m0/s1

propan-2-yl (2S)-2-[[[(2R,3R,4R,5R)-5-(2,4-dioxopyrimidin-1-yl)-4-fluoro-3-hydroxy-4-methyloxolan-2-yl]methoxy-phenoxyphosphoryl]amino]propanoate

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)

Solubility in Formulation 1: ≥ 1.67 mg/mL (3.15 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 16.7 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: ≥ 1.67 mg/mL (3.15 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 16.7 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: ≥ 1.67 mg/mL (3.15 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 16.7 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 4.55 mg/mL (8.59 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.

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