Quantification of sofosbuvir and ledipasvir in human plasma by UPLC-MS/MS method: Application to fasting and fed bioequivalence studies

Sofosbuvir: A comprehensive profile

Sofosbuvir, a nucleotide analogue, is an antiviral medication that belongs to the class of direct-acting antivirals (DAAs). It is primarily used in the treatment of chronic hepatitis C virus (HCV) infections. Sofosbuvir works by inhibiting the replication of HCV, disrupting its ability to produce RNA and effectively reducing the viral load in the body. This chapter offers a comprehensive examination of sofosbuvir, including its nomenclature, physiochemical attributes, synthesis, and thermal analysis. Furthermore, it presents various analytical methods employed for both spectrophotometric and chromatographic assessments of sofosbuvir in different matrices.

Innovative derivative/zero ratio spectrophotometric method for simultaneous determination of sofosbuvir and ledipasvir: Application to average content and uniformity of dosage units

An innovative simple, rapid and sensitive spectrophotometric method was developed for the simultaneous analysis of sofosbuvir (SOF) and ledipasvir (LED) in their combined dosage forms. Sofosbuvir with ledipasvir (SOF/LED) as a combined dosage form was tried at the pandemic COVID 19 crisis. This technique has the advantages of both zero order and first order spectrophotometry. The zero and first derivative amplitudes were measured at 274.2 nm for SOF (zero crossing point of LED in first derivative spectrum) and 314 nm for LED (zero crossing point of SOF in first derivative spectrum) over the concentration range of 2.0-50.0 μg mL^-1 with coefficients of determination (R²) > 0.9999 for both drugs and mean percentage recoveries of 100.25 ± 1.61 and 99.85 ± 0.99 for SOF and LED; respectively. This original method was validated according to ICH requirements and statistically compared to published comparison methods. This method was applied to estimate the average content and the uniformity of dosage units of SOF/LED combined dosage form according to British Pharmacopeia requirements.

Recent advances in the chromatographic determination of the most commonly used anti-hepatitis C drug sofosbuvir and its co-administered drugs in human plasma

Sofosbuvir is a direct-acting antiviral drug that inhibits hepatitis C virus (HCV) NS5B polymerase, which in turn affects the virus replication inside biological systems. The clinical importance of sofosbuvir is based not only on its effect on HCV but also on other lethal viruses such as Zika and severe acute respiratory syndrome coronavirus disease 2019 (SARS-COVID-19). Accordingly, there is a continuous shedding of light on the development and validation of accurate and fast analytical methods for the determination of sofosbuvir in different environments. This work critically reviews the recent advances in chromatographic methods for the analysis of sofosbuvir and/or its metabolites in pure samples, pharmaceutical dosage forms, and in the presence of other co-administered drugs to highlight the current status and future perspectives to enhance its determination in different matrixes.

Rapid and sensitive UHPLC-DAD method for simultaneous determination of sofosbuvir and ledipasvir in human serum

Today, the direct-acting antiviral agents (DAAs) such as sofosbuvir (SOF) and ledipasvir (LED) are widely used to treat the hepatitis virus infection. The aim of this study was to develop a rapid, simple and valid method for simultaneous determination of SOF and LED in human plasma for bioavailability and pharmacokinetic studies. Chromatographic analysis was performed on the C₁₈ column (Blue Orchid, 1.8 μm, 50 × 2 mm) using 0.1 % formic acid in water (pH 2.6) and acetonitrile (60:40; v/v) as mobile phase at a flow rate of 0.5 mL/min. The UV detector was set at 328 nm and 260 nm for analysis of SOF and LED, respectively. To 400 μL of plasma, 100 μL of clonazepam as the internal standard (I.S, 7 μg/mL) was added and the mixture subjected to liquid-liquid extraction using 1000 μL diethyl ether. The calibration curves were linear with coefficients of variation less than 8% for all analyses. The limit of quantification (LOQ) was 20 and 5 ng/mL for SOF and LED, respectively. The results of inter-day and intra-day precision showed good reproducibility and the total analysis time was 1.2 min. This method successfully applied for determination SOF and LED in four healthy volunteers.

Micelle sensitized synchronous spectrofluorimetric approaches for the simultaneous determination of simeprevir and ledipasvir: Application to pharmaceutical formulations and human plasma

Simeprevir (SMV) is commonly co-administered with ledipasvir (LDS) and sofosbuvir (SOF) as an effective combination regimen for treatment naive hepatitis C virus infected patients. In the present study, two spectrofluorimetric approaches were combined together for the development of highly sensitive, rapid, simple and accurate method for simultaneous quantification of SMV and LDS. The native fluorescence intensity values of SMV and LDS were enhanced by the addition of Tween-80 micellar system, while second derivative of the synchronous fluorescence intensity of the drugs at Δλ = 120 nm enabled the determination of both drug concomitantly. Different experimental parameters affecting the synchronous fluorescence of the cited drugs were carefully evaluated for their optimization. The peak amplitudes of the second derivative synchronous fluorimetry were measured at 429 nm for SMV and at 417 nm for LDS. The fluorescence-concentration plots were rectilinear over the range of 60-1500 and 36-540 ng mL^-1 with lower detection limits of 9.0 and 6.0 ng mL^-1 and quantification limits of 27.0 and 17.0 ng mL^-1 for SMV and LDS respectively. The method was successfully applied for the determination of both drugs in their pure forms as well as their pharmaceutical products and human plasma without any significant interference. Statistical comparison with the reported method revealed excellent accuracy and precision of the proposed method.

Micellar high performance liquid chromatographic method for separation and validation of two anti-hepatitis C- virus drugs in pure form, human plasma and human urine

OBJECTIVES

In the present study, an eco- friendly micellar liquid chromatographic technique was validated for separation and quantification of two drugs; namely ribavirin (RIV), and sofosbuvir (SBV) in pure form, pharmaceuticals containing them, human plasma and human urine. These drugs are administered co-administered for treatment of Hepatitis C virus (HCV) that causes hepatitis C in humans.

MATERIAL AND METHODS

These drugs were separated using Nucleosil 100-5 phenyl column. Sodium dodecyl sulphate (SDS) solution (0.05M, pH 7.0) containing triethylamine (0.3%) and n-butanol (10%) was used as a mobile phase with 1.2 mLmin^-1 flow rate and 215nm detection wavelength. Nine minutes were required for resolving the two drugs from the matrix.

RESULTS

The method showed good linearity for RIV and SBV with correlation coefficients (r²) more than 0.9996 within the concentration ranges of (20-400) and (40-400) ngmL^-1 in pure form, (30-300) and (50-300) ngmL^-1 in human plasma and (20-400) and (40-400) ngmL^-1 in human urine, respectively.

CONCLUSION

The recommended method was applied for examination of RIV and SBV in pure and pharmaceuticals. The obtained results were statistically matched with reported methods with no significant differences. Also, the recommended method was effectively applied for estimation of both drugs in spiked human urine and plasma without purification or extraction steps and real samples of plasma and urine of humans having therapy of RIV and SBV, as well as, performing tablets dissolution-rate tests with satisfactory results.

Chemometrically Assisted Development of Ultra-High-Performance Liquid Chromatography Method for the Simultaneous Quantification of Sofosbuvir, Daclatasvir and Ledipasvir in Pharmaceutical Dosage Forms

A new ultra-high-performance liquid chromatography method for the simultaneous quantification of sofosbuvir, daclatasvir and ledipasvir was developed. Two combinations of these direct-acting antivirals are used in hepatitis C virus infection therapy and show high efficacy and safety. Fractional factorial design was used for screening the most influential factors on separation and time analysis. These significant factors were optimized using a central composite design. The optimum resolution was carried out by using a Waters XBridge C18 column (150 mm, 4.6 mm ID, 5 μm) at a temperature of 35°C ± 2°C and acetonitrile/sodium perchlorate buffer (10 mM, pH = 3.2) (40: 60 v/v) as mobile phase at a flow rate of 1.5 mL min-1. UV detection was set at λ = 210 nm. A short chromatographic separation time was achieved. The developed method was validated according to the accuracy profile approach and was found specific, precise, faithful and accurate. The detection limits were between 0.07 and 0.13 μg mL-1. Hence, this novel method can be employed for the routine quality control analysis and in dissolution profile studies of generics containing these products.

A Novel Simultaneous Estimation of Sofosbuvir and Velpatasvir in Human Plasma by Liquid Chromatography Tandem-Mass Spectrometry after Protein Precipitation Method

Objective:

The aim of the present work is to achieve a novel highly sensitive chromatographic method for the simultaneous determination of hepatitis C agents, sofosbuvir and velpatasvir from human plasma using ritonavir as an internal standard.

Methods:

Chromatographic separation was achieved using Hypersil C18 column (50mm x 4.6mm, 3μm) with an isocratic elution mode using the mobile phase composition 10 mM ammonium formate buffer (pH 5.0): acetonitrile (20:80 v/v) pumped at a flow rate of 0.5 ml/min. The detection was carried out by tandem mass spectrometry using Multiple Reaction Monitoring (MRM) positive Electrospray Ionization (ESI) with proton adducts at m/z 530.10 > 243.10, 883.40 > 114.0 and 721.25 > 197.0.

Results:

The method validated as per USFDA guidelines with respect to linearity, accuracy, and precision was found to be acceptable over the concentration range of 0.2–2000 ng/ml and 5-2000 ng/ml for sofosbuvir and velpatasvir respectively and the method was found to be highly sensitive and selective.

Conclusion:

The developed tandem mass spectrometric method is robust and can be applied for the monitoring of plasma levels of the analyzed drug in preclinical and clinical pharmacokinetic studies.

Rapid bioanalytical LC-MS/MS method for the simultaneous determination of sofosbuvir and velpatasvir in human plasma-application to a pharmacokinetic study in Egyptian volunteers

A novel, rapid and validated LC-MS/MS bioanalytical method has been developed for the extraction and determination of sofosbuvir and velpatasvir simultaneously in human plasma using ledipasvir as an internal standard (IS). The simple and reproducible protein precipitation technique with acetonitrile was successfully used for the deproteinization and extraction of the analytes from human plasma matrix. The developed method achieved consistent recoveries over different concentrations with average extraction recoveries of 81.72% and 80.46% for sofosbuvir and velpatasvir, respectively. The chromatographic separation was performed within only 2.80 min as a run time by an isocratic elution through C18 Zorbox eclipse plus (100 × 4.6 mm, 5 μm). Optimum mobile phase consisted of 0.1% formic acid in water: acetonitrile: methanol (30:60:10, v/v/v) pumped at a flow rate of 0.55 mL min^-1 and injection volume was 10 μL. LC-MS/MS detection was done by multiple reaction monitoring transitions operating at positive ionization mode for both analytes and IS. Bioanalytical method validation as per EMA guidelines was carried out where the proposed method revealed linearity over the concentration range of 5-5000 and 10-1500 ng mL^-1 for sofosbuvir and velpatasvir, respectively. After validation, the method was applied to the analysis of the two drugs after a single oral administration of Epclusa 400/100 mg tablets to Egyptian healthy volunteers.

Specific stability indicating spectrofluorimetric method for determination of ledipasvir in the presence of its confirmed degradation products; application in human plasma

A rapid and specific spectrofluorimetric method with higher sensitivity was developed for determination of ledipasvir (LDS) in tablets and human plasma. The proposed method relies on hydrogen bonding formations between the hydroxyl groups of polyoxyethylene 50 stearate and LDS, causing significant enhancement of its native fluorescence. The fluorescence intensity was measured at 430 nm after excitation at 340 nm. The fluorescence-concentration plot was rectilinear over the range 1-400 ng mL^-1 with detection and quantification limits of 0.25 and 1.10 ng mL^-1, respectively. The high sensitivity of the proposed method permits its application for ledipasvir determinations in real human plasma even in the presence of co-administered drugs sofosbuvir and ribavirin. Moreover, the proposed method was further extended to stability studies of ledipasvir after exposure to different forced degradation conditions according to ICH guidelines, along with the structural elucidation of its degradation products utilizing IR and Mass spectra. A proposal for the degradation pathways was presented.

Novel determination of sofosbuvir and velpatasvir in human plasma by UPLC-MS/MS method: Application to a bioequivalence study

A novel and sensitive LC-MS/MS method was developed, optimized and validated for quantification of sofosbuvir (SOF) and velpatasvir (VEL) in human plasma using ledipasvir as an internal standard (IS). Sample preparation was done using acetonitrile for precipitation of plasma proteins. Chromatographic analysis was done on an Acquity UPLC BEH C₁₈ column using 0.1% formic acid and acetonitrile as a mobile phase. The Xevo TQD LC-MS/MS system was run with electrospray ionization mode. The developed method was optimized and then validated according to the US Food and Drug Administration guidelines. Linearity was found to be in the range of 0.25-3500 ng/mL for SOF and 1-1000 ng/mL for VEL. A short run time of 1.5 min allows swift analysis of many plasma samples per day. The developed method was successfully utilized for estimating both SOF and VEL in the plasma of healthy human volunteers participated in a bioequivalence study.

Drug Interchangeability of Generic and Brand Products of Fixed Dose Combination Tablets of Sofosbuvir and Ledipasvir (400/90 mg): Employment of Reference Scaled Average Bioequivalence Study on Healthy Egyptian Volunteers

BACKGROUND AND OBJECTIVES

The purpose of this study was to apply the reference-scaled average bioequivalence (RSABE) approach to evaluate the bioequivalence and to investigate the pharmacokinetic properties of two formulations of fixed dose combination (FDC) tablet of sofosbuvir (SOF) and ledipasvir (LED) (400/90 mg) in 36 healthy Egyptian volunteers.

METHODS

The study was performed in single-dose, randomized-sequence, open-label, reference-replicated, 3-period crossover design (RTR, TRR, RRT), with a washout period of 2 weeks. A rapid and simple LC-MS/MS method was developed and validated for the simultaneous estimation of SOF and LED using eplerenone as an internal standard (IS).

RESULTS

The results showed that the 90% confidence intervals (CIs) for natural log-transformed ratios of C_max, AUC_last and AUC_∞ of SOF (89.95-115.31, 98.77-109.75 and 98.79-109.75) were within the RSABE acceptance limits. The 90% CIs for natural log-transformed ratios of C_max and AUC_last of LED (87.33-115.15 and 83.82-112.26) were within the FDA bioequivalence limits (80.00-125.00). In addition, the in vitro dissolution study was done and both formulations released > 85% of drug within 15 min in the proposed dissolution medium.

CONCLUSIONS

In conclusion, bioequivalence between the two fixed-dose combination products was demonstrated for both active ingredients.

New, simple and sensitive HPTLC method for simultaneous determination of anti-hepatitis C sofosbuvir and ledipasvir in rabbit plasma

Sofosbuvir (SOF) and ledipasvir (LDS) represent anti-hepatitis C binary mixture. Herein, a fast high-performance thin-layer chromatography (HPTLC) method was developed, validated and applied for simultaneous determination of SOF and LDS in biological matrix. An innovative strategy was designed which based on coupling dual wavelength detection with HPTLC. This strategy enabled sensitive, specific, high sample throughput and cost-effective determination of the SOF-LDS binary mixture. The developed HPTLC procedure is based on a simple liquid-liquid extraction, enrichment of the analytes and subsequent separation with UV detection. Separations were performed on HPTLC silica gel 60 F₂₅₄ aluminum plates with a mobile phase consisting of ethyl acetate-glacial acetic acid (100:5, v/v). The R_f values for SOF and LDS were 0.62 and 0.30, respectively. Dual wavelength scanning was carried out in the absorbance mode at 265 and 327 nm for SOF and LDS, respectively. The linear ranges were 40-640 and 9-144 ng/band for SOF and LDS, respectively with correlation coefficients of 0.9998. The detection limits were 10.61 and 2.54 ng/band and the quantitation limits were 32.14 and 7.70 ng/band for SOF and LDS, respectively indicating high sensitivity of the proposed method. Consequently, this permits in vitro and in vivo application of the proposed method in rabbit plasma with good percentage recovery (95.68-103.26%). Validation parameters were assessed according to ICH guidelines. The proposed method represents a simple, high sample throughput and economic alternative to the already existing more complicated reported LC-MS/MS techniques. The method would afford an efficient tool for therapeutic drug monitoring and bioavailability studies of SOF and LDS.

Simultaneous quantitation of two direct acting hepatitis C antivirals (sofosbuvir and daclatasvir) by an HPLC-UV method designated for their pharmacokinetic study in rabbits

Sofosbuvir (SOF) and daclatasvir (DCS) are novel, recently developed direct acting antiviral agents characterized by potent anti-hepatitis C virus action. A fast and efficient HPLC-UV method was developed, validated and applied for simultaneous determination of SOF and DCS in pharmaceutical formulations and biological fluids based on coupling liquid-liquid extraction with ultrasound and dual wavelength detection at λ_max; 260 and 313 nm for SOF and DCS, respectively. This approach provided simple, sensitive, specific and cost-effective determination of the SOF-DCS mixture with good recoveries of the analytes from plasma. Analytes were separated within 7 min on C₁₈ analytical column with acetonitrile-10 mM acetate buffer of pH 5.0 at a flow rate of 1.0 mL min^-1. The linear ranges were 1-20 μg mL^-1 for SOF and 0.6-6 μg mL^-1 for DCS with correlation coefficients ≥0.9995. The detection limits in spiked rabbit plasma were 0.20 and 0.19 μg mL^-1 for SOF and DCS, respectively. The method was validated according to ICH and US-FDA guidelines. Finally, the method was successfully applied for simultaneous pharmacokinetic studies of SOF and DCS in rabbits using rofecoxib as internal standard.

Investigation of anti-Hepatitis C virus, sofosbuvir and daclatasvir, in pure form, human plasma and human urine using micellar monolithic HPLC-UV method and application to pharmacokinetic study

Simultaneous determination of sofosbuvir (SOF), and daclatasvir (DAC) in their dosage forms, human urine and human plasma using simple and rapid micellar high performance liquid chromatographic method coupled with UV detection (HPLC-UV) had been developed and validated. These drugs are described as co-administered for treatment of Hepatitis C virus (HCV). HCV is the cause of Hepatitis C and some cancers such as liver cancer (hepatocellular carcinoma) and lymphomas in humans. Separation and quantitation were carried out on anonyx™ C₈ monolithic (100 × 4.6 mm (i.d.) analytical column maintained at 25 °C. The mobile phase consisted of 0.1 M sodium dodecyl sulfate (SDS) solution containing 20% (V/V) n-propanolol and 0.3% (V/V) triethylamine and pH was adjusted to 6.5 using 0.02 M phosphoric acid, respectively. The retention times of SOF and DAC were 4.8 min, and 6.5 min, respectively. Measurements were made at flow rate of 0.5 mL/min with injection volume of 20 μL and ultraviolet (UV) detection at 226 nm. Linearity of SOF and DAC was obtained over concentration ranges of 50-400, and 40-400 ng/mL, respectively in pure form, 60-300 and 50-300 ng/mL, respectively for human plasma and over 50-400, and 40-400 ng/mL, respectively for human urine with correlation coefficient >0.999. The proposed method demonstrated excellent intra- and inter-day precision and accuracy. The suggested method was applied for determination of the drugs in pure, dosage form, and in real human plasma, real human urine and drug-dissolution test of their tablets. The obtained results have been statistically compared to reported method to give a conclusion that there is no significant differences.

Chemometric simultaneous determination of Sofosbuvir and Ledipasvir in pharmaceutical dosage form

Partial least squares (PLS), different families of continuous wavelet transform (CWT), and first derivative spectrophotometry (DS) techniques were studied for quantification of Sofosbuvir (SFB) and Ledipasvir (LDV) simultaneously without separation step. The components were dissolved in Acetonitrile and the spectral behaviors were evaluated in the range of 200 to 400nm. The ultraviolet (UV) absorbance of LDV exhibits no interferences between 300 and 400nm and it was decided to predict the LDV amount through the classic spectrophotometry (CS) method in this spectral region as well. Data matrix of concentrations and calibrated models were developed, and then by applying a validation set the accuracy and precision of each model were studied. Actual concentrations versus predicted concentrations plotted and good correlation coefficients by each method resulted. Pharmaceutical dosage form was quantified by developed methods and the results were compared with the High Performance Liquid Chromatography (HPLC) reference method. Analysis Of Variance (ANOVA) in 95% confidence level showed no significant differences among methods.

Comparison between core-shell and totally porous particle stationary phases for fast and green LC determination of five hepatitis-C antiviral drugs

The performances of core-shell 2.7 μm and fully porous sub-2 μm particles packed in narrow diameter columns were compared under the same chromatographic conditions. The stationary phases were compared for fast separation and determination of five new antiviral drugs; daclatasvir, sofosbuvir, velpatasvir, simeprevir, and ledipasvir. The gradient elution was done using ethanol as green organic modifier, which is more environmentally friendly. Although both columns provided very good resolution of the five drugs, core-shell particles had proven to be of better efficiency. Under gradient elution conditions, core-shell particles exhibited faster elution, better peak shape, and enhanced resolution adding to lower system backpressure. The column backpressure on sub-2 μm particles was more than twice that on core-shell particles. This gives a chance to use conventional high-performance liquid chromatography conditions without needing special instrumentation as that required for ultra-high performance liquid chromatography. The method was validated for determination of the five drugs by gradient elution using mobile phase composed of organic modifier ethanol and aqueous part containing 0.75 g sodium octane sufonate and 3.0 g sodium dihydrogen phosphate per liter at pH of 6.15. Detection was done using UV-detector set at 210 nm. The linearity, accuracy, and precision were found very good within the concentration range of 2-200 μg/mL.

Ultrasensitive spectrofluorimetric method for rapid determination of daclatasvir and ledipasvir in human plasma and pharmaceutical formulations

Direct-acting antivirals (DAAs) represent a revolution in the treatment of chronic hepatitis C which have emerged at an extremely rapid pace over the past few years. DAAs act directly on the hepatitis C virus at various points in the viral life cycle to inhibit viral production. Among these novel DAAs, are daclatasvir (DCS) and ledipasvir (LDS). Herein, a novel, fast, simple, ultrasensitive and cost-effective spectrofluorimetric method was designed for determination of DCS and LDS in miscellaneous matrices. The method is based on investigation of the native fluorescence of the cited drugs. The relative fluorescence intensity (RFI) was measured at λ_ex/λ_em equal to 315/381 nm for DCS and 332/387 nm for LDS. Under the optimum conditions, the linear ranges of calibration curves were 0.2-30 and 6-120 ng mL^-1 for DCS and LDS, respectively with correlation coefficients ≥0.9998. The detection limits were 0.047 and 1.939 ng mL^-1 for DCS and LDS, respectively indicating ultrasensitivity of the proposed method. Consequently, this permits in vitro and in vivo application of the proposed method in spiked and real human plasma with good percentage recovery (96.6-103.6%). The method was validated in compliance with ICH guidelines and US-FDA guidelines. Furthermore, the application was extended to analysis of DCS and LDS in its pharmaceutical formulations (either alone or in presence of other co-formulated drugs) and in synthetic mixture with sofosbuvir or ribavirin.

UPLC-MS/MS method for the simultaneous quantification of sofosbuvir, sofosbuvir metabolite (GS-331007) and daclatasvir in plasma of HIV/HCV co-infected patients

Direct-acting antiviral agents (DAAs) represent the major advance in hepatitis C virus (HCV) infection treatment leading to extremely high eradication rates in HCV mono- and HIV/HCV co-infected patients. In this scenery, availability of Therapeutic Drug Monitoring (TDM) is of interest to assess plasma concentrations to prevent either therapeutic failure due to suboptimal medication adherence and drug-drug interactions or avoid adverse events. Aim of this study was to develop and validate an Ultra-Performance Liquid Chromatography Mass Spectrometry (UPLC-MS/MS) method for the simultaneous quantification of sofosbuvir, sofosbuvir metabolite (GS-331007), and daclatasvir in human plasma. A simple protein precipitation was applied by adding 200 μL acetonitrile with internal standard 6,7-Dimethyl- 2,3-di(2-pyridyl) quinoxaline to 100 μL plasma sample. Drug separation was performed on analytical C-18 Luna Omega column (50 mm × 2.1 mm I.D.) with particle size of 1.6 μm. The mobile phase consisting of water containing 0.1% formic acid and acetonitrile at flow 0.4 mL/min and a gradient run time of 3.5 min. The injection volume was 10 μL. Anti-HCV drugs were detected in positive electrospray ionization mode. The full scan mass spectral analyses of sofosbuvir, GS-331007, daclatasvir and quinaxoline showed protonated molecule ions and transitions m/z: 530.098 → 243.02, 260.93 → 112.94, 739.4 → 339.27 and 313.03 → 77.99 respectively. The linearity of standard curves was excellent (r² > 0.99), the absolute recovery of anti-HCV drugs ranged between 95 and 98%, and both imprecision and inaccuracy were <15% according to FDA guidelines. The UPLC-MS/MS method was applied to 16 plasma samples of as many HIV/HCV co-infected patients treated with sofosbuvir and daclatasvir. While sofosbuvir was not detectable in all samples, the median plasma concentrations of daclatasvir and GS-331007 were 223.6 ± 319.56 ng/mL and 537.11 ± 242.09 ng/mL, respectively. In conclusion, we describe an UPLC-MS/MS method allowing the simultaneous quantification of sofosbuvir, GS-331007 and daclatasvir in plasma samples. The method was sensitive, specific, robust, and time-saving.

Simultaneous determination of the brand new two-drug combination for the treatment of hepatitis C: Sofosbuvir/ledipasvir using smart spectrophotometric methods manipulating ratio spectra

In this work, various sensitive and selective spectrophotometric methods were first introduced for the simultaneous determination of sofosbuvir and ledipasvir in their binary mixture without preliminary separation. Ledipasvir was determined simply by zero-order spectrophotometric method at its λ_max=333.0nm in a linear range of 2.5-30.0μg/ml without any interference of sofosbuvir even in low or high concentrations and with mean percentage recovery of 100.05±0.632. Sofosbuvir can be quantitatively estimated by one of the following smart spectrophotometric methods based on ratio spectra developed for the resolution of the overlapped spectra of their binary mixture; ratio difference spectrophotometric method (RD) by computing the difference between the amplitudes of sofosbuvir ratio spectra at 228nm and 270nm, first derivative (DD¹) of ratio spectra by measuring the sum of amplitude of trough and peak at 265nm and 277nm, respectively, ratio subtraction (RS) spectrophotometric method in which sofosbuvir can be successfully determined at its λ_max=261.0nm and mean centering (MC) of ratio spectra by measuring the mean centering values at 270nm. All of the above mentioned spectrophotometric methods can estimate sofosbuvir in a linear range of 7.5-90.0μg/ml with mean percentage recoveries of 100.57±0.810, 99.92±0.759, 99.51±0.475 and 100.75±0.672, respectively. These methods were successfully applied to the analysis of their combined dosage form and bulk powder. The adopted methods were also validated as per ICH guidelines and statistically compared to an in-house HPLC method.

Current antiviral drugs and their analysis in biological materials - Part II: Antivirals against hepatitis and HIV viruses

This review is a Part II of the series aiming to provide comprehensive overview of currently used antiviral drugs and to show modern approaches to their analysis. While in the Part I antivirals against herpes viruses and antivirals against respiratory viruses were addressed, this part concerns antivirals against hepatitis viruses (B and C) and human immunodeficiency virus (HIV). Many novel antivirals against hepatitis C virus (HCV) and HIV have been introduced into the clinical practice over the last decade. The recent broadening portfolio of these groups of antivirals is reflected in increasing number of developed analytical methods required to meet the needs of clinical terrain. Part II summarizes the mechanisms of action of antivirals against hepatitis B virus (HBV), HCV, and HIV, their use in clinical practice, and analytical methods for individual classes. It also provides expert opinion on state of art in the field of bioanalysis of these drugs. Analytical methods reflect novelty of these chemical structures and use by far the most current approaches, such as simple and high-throughput sample preparation and fast separation, often by means of UHPLC-MS/MS. Proper method validation based on requirements of bioanalytical guidelines is an inherent part of the developed methods.

Development a validated highly sensitive LC-MS/MS method for simultaneous quantification of Ledipasvir, sofosbuvir and its major metabolite GS-331007 in human plasma: Application to a human pharmacokinetic study

A highly sensitive and rapid LC-MS/MS method was developed, fully optimized and validated for the simultaneous determination of Ledipasvir (LED) and Sofosbuvir (SOF) in the presence of its major metabolite GS-331007 in human plasma using Daclatasvir as internal standard (IS). The extraction of analytes and IS from plasma was performed using liquid-liquid extraction with ethyl acetate. The chromatographic separation of these prepared samples was achieved on Xterra MS C₈ column (4.6×50mm,5μm) using gradient elution with a mobile phase of ammonium formate buffer (pH 3.5; 10mM), acetonitrile and methanol pumped at a flow rate 0.7mLmin^-1.The detection was performed on API4000 triple quadrupole tandem mass spectrometer using multiple reaction monitoring (MRM) positive electrospray ionization interface. The method was validated according to FDA guidelines for bio-analytical methods with respect to linearity, accuracy, precision, selectivity, carry-over, stability and dilution integrity. Linearity was obtained over a concentration range of 0.1-1000, 0.3-3000 and 3.0-3000ngmL^-1 for LED, SOF and GS-331007; respectively by applying weighted least-squares linear regression method (1/x²). The wider range of quantification in a shorter period of separation time less than 5.0min allowed monitoring the serum concentration of analytes up to 144h. The proposed method can be successfully applied for pharmacokinetic and bioequivalence studies in healthy human volunteers.

UPLC-MS/MS method for determination of sofosbuvir in human plasma

INTRODUCTION

A sensitive and rapid method for quantitation of Sofosbuvir in human plasma has been established using ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS).

MATERIALS AND METHODS

Sofosbuvir d3 was used as an internal standard. Sofosbuvir and internal standard in plasma sample were extracted using ethyl acetate (liquid liquid extraction). A centrifuged upper layer was then evaporated and reconstituted with the mobile phase of 0.5% formic acid: methanol (30:70, v/v). The reconstituted samples were injected into a Gemini C18 (50×4.6mm, 5μm) column.

RESULTS

Using MS/MS in the multiple reaction monitoring mode, Sofosbuvir and Sofosbuvir d3 were detected without severe interferences from human plasma matrix. Sofosbuvir produced a protonated precursor ion ([M+H]⁺) at m/z 428.35 and a corresponding product ion at m/z 279.26. The internal standard produced a protonated precursor ion ([M+H]⁺) at m/z 431.38 and a corresponding product ion at m/z 282.37. The calibration curves for the analyte was linear (R²≥0.9956, n=4) over the concentration range of 4.063-8000.010ng/mL. Stability studies revealed that Sofosbuvir was stable in plasma during bench top (7h at room temperature), in injector (20h), at the end of five successive freeze and thaw cycles and long term at -70°C±15°C for 15 days.

CONCLUSION

The developed method was validated as per the guidelines of USFDA and the obtained results were found to be within the limits and could be successfully employed for the determination of Sofosbuvir in human plasma for regular and pharmacokinetic studies.