Safety of Sofosbuvir in People With Advanced Kidney Failure
Safety of Sofosbuvir in People With Advanced Kidney Failure
Infection with hepatitis C virus (HCV), a hepatotropic RNA virus, is often chronic, and
 causes liver cirrhosis and liver cancer. The virus is transmitted through parenteral
 exposure. This infection is particularly common in those on maintenance hemodialysis.

 Sofosbuvir, an inhibitor of HCV RNA-dependent RNA polymerase, forms the backbone of DAA-based
 anti-HCV treatment regimens. In pre-clinical pharmacokinetic studies, administration of the
 usual 400 mg daily dose to in presence of advanced kidney failure (estimated glomerular
 filtration rate [eGFR] of <30 ml/min) showed that serum levels of the sofosbuvir and
 GS-331007, the primary metabolite of sofosbuvir, were elevated by several folds. Hence,
 sofosbuvir is not approved for use in people on maintenance hemodialysis.

 The newer DAAs (e.g. grazoprevir/elbasvir combination), which have been approved for use in
 people with eGFR <30 ml/min, are very costly and are not available in Asian countries
 including India. Hence, as a rescue measures, several physicians, including our group, have
 tried half-daily dose (i.e, 200 mg daily or 400mg on alternate days) of sofosbuvir and 60 mg
 daclatasvir in dialysis-dependent people, with good results in terms of both safety and
 efficacy. In fact, the use of this empirical 200 mg daily dose schedule has become common in
 clinical practice. However, this use is not based on any pharmacokinetic data.

 Hence, it is proposed to study the pharmacokinetics of low-dose (200 mg daily or 400 mg
 alternate day) of sofosbuvir and GS-331007 metabolite in people with eGFR <30/min and active
 HCV infection.
Study design Three arms, observational, pharmacokinetic study

 Study duration Two years (March 2019-February 2020)

 Study participants Two groups of participants will be included (i) People without chronic
 kidney disease, i.e, normal eGFR and infected with HCV infection (ii) People with chronic
 kidney disease and eGFR <30 ml/min and infected with HCV infection

 We will include a total of thirty participants with ten in each of the three groups: Group A
 (ESRD, alternate day dose), Group B (ESRD, daily dose) and Group C (normal eGFR)

 Drug schedule Participants with eGFR <30 ml/min: will be given daclatasvir 60 mg once daily
 along with either sofosbuvir (200 mg) daily once or sofosbuvir 400mg once every alternate day
 Participants with normal renal function will be treated with sofosbuvir 400mg and daclatasvir
 60 mg once daily.

 The treatment duration will be 12 weeks for alll there three study groups.

 Dialysis schedule A four to five hour hemodialysis sessions will be provided twice in a week

 Plan for pharmacokinetic study (i) Molecules: Sofosbuvir and GS331007 (ii) Method: Liquid
 chromatography-tandem mass spectrometry (iii) Specimen collection (~2 ml each time) will be
 done as follows: Hour '0', 0.25, 0.5, 1, 2, 4, 8, 12, 16, 24 [Day 1]; hour 36 [Day 2]; hour
 84 [Day 4], and hour 156 [Day 7].

 Sample Collection, Transport and Storage Soon after sample collection, serum will be
 separated by centrifugation at 4000×g for 10 min at 4°C and separated serum will stored at
 -80°C till analysis. Analysis will be done using validated bioanalytical method at CSIR-CDRI,
 Lucknow.

 Inactivation of hepatitis C virus in the stored sample HCV inactivation will be done by heat
 treatment. Before heat treatment, water bath chamber will be cleaned, filled with fresh RO
 water and temperature calibration will be checked for accuracy. The specimens will be heated
 at 60 C for 10 minutes or 65 C for 5 minutes to inactivate the virus. Immediately after heat
 treatment, the specimens will be put in crushed ice to stop the heat effect. The specimens
 will be transported in frozen condition for analysis.

 Sample preparation:

 The sample preparation consists of the simple liquid-liquid extraction and/or protein
 precipitation.

 Liquid chromatography-mass spectroscopy HPLC system consisting of Shimadzu UFLC system
 consisting of LC-20AD binary pumps and SIL-HTc autosampler (Shimadzu Corporation, Kyoto,
 Japan) will be used to inject 10 µL aliquots of the processed samples on a C18 column (4.6 mm
 × 50 mm, 5.0 µm). The separation will be achieved by running the mobile phase in isocratic
 mode containing acetonitrile and 10mM ammonium acetate buffer in suitable ratio (%v/v) at a
 flow rate capable of sufficient resolution to be optimized during method development and
 validation. The mobile phase will be duly filtered through 0.22 µm filter and degassed
 ultrasonically before use. Mass spectrometric detection will be performed on an API 5500 Q
 Trap mass spectrometer (Applied Biosystems, MDS Sciex Toronto, Canada) equipped with an API
 electron spray ionization (ESI) source. The ion spray voltage will be set at 5500 V. The
 instrument related parameters viz., nebulizer gas, curtain gas, auxiliary gas and collision
 gas and coompound related parameters viz., declustering potential (DP), collision energy
 (CE), entrance potential (EP) and collision cell exit potential (CXP) respectively will be
 optimized before validating the method . Zero air will be used as source gas while nitrogen
 will be used as both curtain and collision gas. The mass spectrometer will be operated at ESI
 positive as well as ESI negative ion mode and detection of the ions will be performed in the
 multiple reaction monitoring (MRM) mode monitering the transitions of the analytes.
 Quadrupole 1 and quadrupole 3 will be maintained at unit resolution and dwell time will be
 set at 200 ms. Analyst 1.6 software (version 1.6, Built 3773; AB Sciex, Toronto, Canada) will
 be used for data acquisition and quantitation.

 Pharmacokinetic parameters estimation The pharmacokinetic parameters will be estimated using
 WinNonlin software either through compartment/non-compartment modeling.
Inclusion Criteria:

 -  Participants with:

 -  hepatitis C virus infection with detectable HCV RNA in blood

 -  naïve to direct acting antiviral drugs based anti-HCV treatment

 Exclusion Criteria:

 -  Hepatitis B virus co-infection

 -  Human immunodeficiency virus co-infection

 -  Clinical evidence of cirrhosis or portal hypertension such as ascites, esophageal or
 gastric varices on esophago-gastro-duodenoscopy, liver stiffness more than 15 KPa as
 measured with transient elastography or history of hepatic encephalopathy.