In vitro studies in human liver microsomes showed that sofosbuvir was an efficient substrate for Cathepsin A (Cat A) and carboxyl esterase 1 (CES1). There were no indications of metabolism via urdine diphosphate glucuronosyltransferases (UGTs) or flavin-containing monooxygenase (FMO). Sofosbuvir was cleaved by CatA and CES1 and subsequent activation steps included amino acid removal by histidine triad nucleotide-binding protein 1 (HINT1) and phosphorylation by uridine monophosphate-cytidine monophosphate (UMP-CMP) kinase and nucleoside diphosphate (NDP) kinase. In vitro data indicated that Cat A preferentially hydrolysed sofosbuvir (the S-diastereomer) while CES1 did not exhibit stereoselectivity. This would be consistent with studies using GS-9851 showing a less efficient metabolism to the triphosphate in the hepatically-derived cell line containing the Clone A replicon and shown to exhibit low CES 1 activity, but high Cat A activity compared with primary human hepatocytes. Following incubation of hepatocytes from rat, dog, monkey and human GS-9851 was converted to the triphosphate GS-461203 in all species, most efficiently in human. Sofosbuvir was also readily converted to the triphosphate in dog liver after oral doses and was the dominant metabolite at all time points assessed with a long half-life of approx. 18 hours. The active metabolite GS-461203 could not be detected in monkey. Further while GS-461203 was detected in rat liver, it could not be measured in liver from mouse.
Sofosbuvir is extensively metabolized in the liver to form the pharmacologically active nucleoside analog triphosphate GS-461203. The metabolic activation pathway involves sequential hydrolysis of the carboxyl ester moiety catalyzed by human cathepsin A (CatA) or carboxylesterase 1 (CES1) and phosphoramidate cleavage by histidine triad nucleotide-binding protein 1 (HINT1) followed by phosphorylation by the pyrimidine nucleotide biosynthesis pathway. Dephosphorylation results in the formation of nucleoside metabolite GS-331007 that cannot be efficiently 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 material in all species and all matrices. In plasma, urine and feces of all species administered sofosbuvir the primary metabolite detected was GS-331007 accounting for >80% of total exposure. In rat liver and plasma GS-566500 was also detected. The metabolite profile was overall comparable between non-pregnant, pregnant and postpartum rats and in milk of postpartum rats with GS-331007 and 2 sulfate conjugates of GS-331007 being the major metabolites.
In dog following a single oral dose of 20 mg/kg of sofosbuvir three metabolites in plasma were identified, GS-331007, GS-566500 and M4 (proposed glucuronidation product of GS-606965), accounting for 93.4%, 1.6% and 0.5%, respectively of total plasma AUC. Parent compound amounted to 4.5%. In dog (and mouse) the majority of a radioactive dose was recovered in urine within 8 to 12 hours.
In male rats given a single oral dose of 20 mg/kg of sofosbuvir, the major metabolite in plasma was GS-331007 (M1) accounting for 84.2% of area under the concentration-time curve (AUC) of total plasma radioactivity. GS-566500 (M2) was observed in plasma at levels of 10.6%. In urine GS-331007 and GS-566500 were major components. In another study using female rats plasma M1 was 53.9% and M2 was present at 14.2%. In rat liver three metabolites, M1 (4.8%, GS-331007), M2 (0.9%, GS-566500) and M3 (GS-606965) were observed, the latter a minor component. The parent compound was not detected in plasma, urine or faeces. The major pathway in rat was hydrolysis of GS-7977 to GS-331007 and minor pathways were hydrolysis of GS-7977 to GS-566500 and GS-606965.
In large randomized controlled trials, serum enzymes elevations were uncommon in patients treated with sofosbuvir despite the fact that the patients being treated had chronic liver disease. In most situations, serum aminotransferase levels improved rapidly upon initiating sofosbuvir therapy, and de novo, late elevations of ALT above 3 times the upper limit of normal (ULN) were uncommon and less frequent than with placebo or no therapy. In multiple, large clinical trials sofosbuvir has not been linked to instances of clinically apparent liver injury with jaundice. Because sofosbuvir is always used with other antiviral agents, it is not always possible to separate the relative role of sofosbuvir from other drugs in causing adverse reactions.
Two rare and unusual forms of liver injury of uncertain relationship to sofosbuvir have been described in patients with receiving antiviral therapy for hepatitis C: sudden hepatic decompensation in patients with preexisting cirrhosis and reactivation of hepatitis B in patients with preexisting evidence of HBV infection.
A rare, but striking liver injury associated with sofosbuvir (and perhaps other potent agents active against HCV) is hepatic decompensation occurring in patients with preexisting cirrhosis. In several instances, decompensation occurred within 2 to 6 weeks of starting therapy (Case 1), while in others it occurred late during therapy or in the immediate posttreatment period. The typical pattern of onset was a progressive rise in bilirubin with signs of hepatic failure such as prolongation of the prothrombin time, decrease in serum albumin and appearance of ascites and hepatic encephalopathy. In many (but not all) instances, serum enzyme levels did not change or increased only slightly in comparison to pretreatment values. In all instances, sofosbuvir was being used in combination with other antiviral agents, such as peginterferon, simeprevir, daclatasvir or ledipasvir, and the specific role of sofosbuvir has been difficult to define. The decompensation usually coincided with rapid viral clearance and patients who survived the episode often had a sustained virological response. The cause of this decompensation is not clear, but it may represent a response to HCV viral eradication (on-target effect) rather than toxicity of the administered antiviral agents (off-target effect on the liver). Alternatively, the injury may be coincidental and unrelated to therapy.
A second form of liver injury that can occur with sofosbuvir therapy and perhaps other potent anti-HCV agents is reactivation of hepatitis B. Instances of clinically apparent hepatitis with rises in serum HBV DNA levels have been reported in patients with chronic hepatitis C who were HBsAg positive and had low levels of HBV DNA which were not thought to be the cause of the chronic liver disease (Case 2). Reactivation has also been described in patients who have anti-HBc without HBsAg in serum, a pattern that suggests previous recovery from hepatitis B. HBV reactivation typically arises within 2 to 8 weeks of starting therapy for hepatitis C and it can be clinically manifest with symptoms of acute hepatitis and marked elevations in serum aminotransferase levels and bilirubin. Instances of death from HBV reactivation have been reported with sofosbuvir therapy. The cause of reactivation is unclear, but it may reflect the eradication of HCV replication which has a nonspecific suppressive effect on HBV replication. Alternatively, the change in immune reactivity with sudden clearance of HCV or as a result of a direct activity of the antiviral agents may alter the replicative status of HBV.
Likelihood score: E* (unproven but suspected cause of clinically apparent liver injury in susceptible individuals).
Concomitant use of rifampin, a potent inducer of P-gp in the intestine, and sofosbuvir may cause decreased plasma concentrations of sofosbuvir and GS-331007 and may lead to decreased therapeutic effect of sofosbuvir. Rifampin and sofosbuvir should not be used concomitantly.
Rifabutin is expected to cause decreased plasma concentrations of sofosbuvir and GS-331007, which may lead to decreased therapeutic effect of sofosbuvir. Concomitant use of rifabutin and sofosbuvir is not recommended.
When used concomitantly with sofosbuvir, certain anticonvulsants (i.e., carbamazepine, oxcarbazepine, phenobarbital, phenytoin) are expected to decrease plasma concentrations of sofosbuvir and GS-331007, which may lead to decreased therapeutic effect of sofosbuvir. Concomitant use of these anticonvulsants and sofosbuvir is not recommended.
Sofosbuvir is a substrate of breast cancer resistance protein (BCRP); GS-331007 is not a BCRP substrate. Inhibitors of BCRP may cause increased plasma concentrations of sofosbuvir without increasing plasma concentrations of GS-331007. Sofosbuvir and GS-331007 are not BCRP inhibitors; pharmacokinetic interactions are unlikely with drugs that are BCRP substrates.
Sofosbuvir is approximately 61-65% bound to human plasma proteins and the binding is independent of drug concentration over the range of 1 ug/mL to 20 ug/mL. Protein binding of GS-331007 was minimal in human plasma. After a single 400 mg dose of (14)C-sofosbuvir in healthy subjects, the blood to plasma ratio of (14)C-radioactivity was approximately 0.7.
The pharmacokinetic properties of sofosbuvir and the predominant circulating metabolite GS-331007 have been evaluated in healthy adult subjects and in subjects with chronic hepatitis C. Following oral administration of SOVALDI, sofosbuvir was absorbed with a peak plasma concentration observed at approximately 0.5-2 hour post-dose, regardless of dose level. Peak plasma concentration of GS-331007 was observed between 2 to 4 hours post-dose. Based on population pharmacokinetic analysis in subjects with genotype 1 to 6 HCV infection who were coadministered ribavirin (with or without pegylated interferon), geometric mean steady state AUC0-24 was 969 ng*hr/mL for sofosbuvir (N=838), and 6790 ng*hr/mL for GS-331007 (N=1695), respectively. Relative to healthy subjects administered sofosbuvir alone (N = 272), the sofosbuvir AUC0-24 was 60% higher; and GS-331007 AUC0-24 was 39% lower, respectively, in HCV-infected subjects. Sofosbuvir and GS-331007 AUCs are near dose proportional over the dose range of 200 mg to 1200 mg.
Following a single 400 mg oral dose of (14)C-sofosbuvir, mean total recovery of the dose was greater than 92%, consisting of approximately 80%, 14%, and 2.5% recovered in urine, feces, and expired air, respectively. The majority of the sofosbuvir dose recovered in urine was GS-331007 (78%) while 3.5% was recovered as sofosbuvir. These data indicate that renal clearance is the major elimination pathway for GS-331007.
Studies in pregnant rats showed that sofosbuvir crossed the placenta. Fetal blood and brain sofosbuvir derived radioactivity was higher than in dams, but fetal liver and kidney had lower levels than corresponding organs in dams. Sofosbuvir-derived radioactivity was also quantifiable in milk from day 2 postpartum rats, but nursing pups did not appear to be extensively exposed to drug-derived radioactivity. Milk to plasma ratios were 0.1 at 1 hour and 0.8 at 24 hours.
[EN] 2'-SUBSTITUTED NUCLEOSIDE DERIVATIVES AND METHODS OF USE THEREOF FOR THE TREATMENT OF VIRAL DISEASES<br/>[FR] DÉRIVÉS DE NUCLÉOSIDE 2'-SUBSTITUÉS ET PROCÉDÉS D'UTILISATION DE CEUX-CI POUR LE TRAITEMENT DE MALADIES VIRALES
申请人：MERCK SHARP & DOHME
公开号：WO2012142085A1
公开（公告）日：2012-10-18
The present invention relates to 2'-Substituted Nucleoside Derivatives of Formula (I): and pharmaceutically acceptable salts thereof, wherein A, B, X, R1, R2 and R3 are as defined herein. The present invention also relates to compositions comprising at least one 2'-Substituted Nucleoside Derivative, and methods of using the 2'-Substituted Nucleoside Derivatives for treating or preventing HCV infection in a patient.
2'-AZIDO SUBSTITUTED NUCLEOSIDE DERIVATIVES AND METHODS OF USE THEREOF FOR THE TREATMENT OF VIRAL DISEASES
申请人：Girijavallabhan Vinay
公开号：US20140206640A1
公开（公告）日：2014-07-24
The present invention relates to 2′-Azido Substituted Nucleoside Derivatives of Formula (I): and pharmaceutically acceptable salts thereof, wherein B, X, R
1
, R
2
and R
3
are as defined herein. The present invention also relates to compositions comprising at least one 2′-Azido Substituted Nucleoside Derivative, and methods of using the 2′-Azido Substituted Nucleoside Derivatives for treating or preventing HCV infection in a patient.
[EN] 2'-METHYL SUBSTITUTED NUCLEOSIDE DERIVATIVES AND METHODS OF USE THEREOF FOR THE TREATMENT OF VIRAL DISEASES<br/>[FR] DÉRIVÉS DE NUCLÉOSIDES 2'-MÉTHYLE SUBSTITUÉS ET LEURS PROCÉDÉS D'UTILISATION DANS LE TRAITEMENT DE MALADIES VIRALES
申请人：MERCK SHARP & DOHME
公开号：WO2014062596A1
公开（公告）日：2014-04-24
The present invention relates to 2'-Methyl Substituted Nucleoside Derivatives of Formula (I): and pharmaceutically acceptable salts thereof, wherein R, R1, R2 and R3, are as defined herein. The present invention also relates to compositions comprising at least one 2'-Methyl Substituted Nucleoside Derivative, and methods of using the 2'-Methyl Substituted Nucleoside Derivatives for treating or preventing HCV infection in a patient.
[EN] SELECTIVE PROCESS FOR SYNTHESIS OF NUCLEOSIDE PHOSPHORAMIDATES<br/>[FR] PROCÉDÉ SÉLECTIF POUR LA SYNTHÈSE DE PHOSPHORAMIDATES DE NUCLÉOSIDE
申请人：SANDOZ AG
公开号：WO2016189040A1
公开（公告）日：2016-12-01
A process for preparing a nucleoside phosphoramidate, in particular to a process for preparing sofosbuvir, wherein a phosphoramidate derivative is used as starting material.
