Innovative Spectrophotometric Methods for Determination of Newly Discovered Combination for Hepatitis C Treatment

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.

Feasible TLC-Spectro-Densitometry Technique for Simultaneous Determination of Two Hepatitis C Antiviral Drugs, Sofosbuvir and Simeprevir: Application to Combined Pharmaceutical Dosage Forms and Human Plasma

A high-performance thin-layer chromatographic method was developed and validated for the concurrent determination of simeprevir (SMV) and sofosbuvir (SOF). The chromatographic separation was attained on silica gel 60 F254 as stationary phase and ethyl acetate-hexane-methanol (5.0:4.0:1.0, v/v/v) as developing solvent with UV detection at 273 nm. The RF values were 0.67±0.02 and 0.43±0.02 for SMV and SOF, respectively. The method has been validated in respect to the guidelines of the International Conference on Harmonization. Linearity was maintained between 60-1,000 and 70-1,200 ng/band for SMV and SOF, respectively, with good correlation coefficients (0.9993-0.9997) for both drugs. The suggested method was highly sensitive as the calculated detection limits were 15 and 22 ng/band, while the quantitation limits were 44 and 66 ng/ band for SMV and SOF, respectively. The suggested methodology has been effectively employed for the determination of the mentioned drugs in their pure forms and their pharmaceutical dosage forms as well as human plasma without significant interference of the pharmaceutical excipients or plasma components.

Analytical Methods for Determination of Antiviral Drugs in Different Matrices: Recent Advances and Trends

Viruses are the main pathogenic substances that cause severe diseases in humans and other living things. They are among the most common microorganisms, and consequently, antiviral drugs have emerged to prevent and treat viral infections. Antiviral drugs are an essential drug group considering their prescription and consumption rates for different diseases and indications. Therefore, it is crucial to develop accurate and precise analytical methods to detect antiviral drugs in various matrices. Chromatographic techniques are used frequently for the quantification purpose since they allow simultaneous determination of antivirals. Electrochemical methods have also gained importance since the analysis can be performed quickly without the need for pretreatment. Spectrophotometric and spectrofluorimetric methods are used because they are simple, inexpensive, and less time-consuming methods. The purpose of this review is to present an overview of the analysis of currently used antiviral drugs from 2010 to 2021. Since studies on antiviral drugs are numerous, selected publications were reviewed in this article. The analysis of antiviral drugs was divided into three main groups: chromatographic, spectrometric, and electrochemical methods which were applied to different matrices, including pharmaceutical, biological, and environmental samples.

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.

Earth-friendly spectrophotometric methods for simultaneous determination of ledipasvir and sofosbuvir: Application to average content and uniformity of dosage unit testing

Simple, rapid, sensitive, accurate, precise and earth-friendly spectrophotometric methods were developed for the simultaneous analysis of ledipasvir (LED) and sofosbuvir (SOF) without interference of both sunset yellow dye and copovidone excipients (the most probable interferents) in their combined dosage form. These proposed methods were based on measurement of LED in synthetic mixtures and combined dosage form by first derivative (¹D) spectrophotometry at 314 nm over the concentration range of 2-50 μg mL^-1 with coefficient of determination (R²) > 0.9999, mean percentage recovery of 99.98 ± 0.62. On the other hand, SOF in synthetic mixtures and combined dosage form was determined by five methods. Method I is based on the use of ¹D spectrophotometry at 274.2 nm (zero crossing point of LED). Method II involves the application of conventional dual wavelength method (DW) at the absolute difference between SOF zero order amplitudes at 261 nm (λ_max of SOF) and 364.7 nm. At these wavelengths, the absolute difference between LED zero order amplitudes was observed to equal zero. Method III depends on isosbestic point method (ISP) in which the total concentration of both drugs was measured at isosbestic point at 262.7 nm. Concentration of SOF could be obtained by subtraction of LED concentration. While, method IV depends on absorbance correction method (absorption factor method), which is based on determination of SOF concentration at 262.7 nm (λ_ISP) and LED at 333 nm (λ_max of LED). Finally, method V depends on absorbance ratio method (Q-analysis) in which 262.7 nm (λ_ISP) and 261 nm (λ_max of SOF) were selected to determine SOF concentration. The linearity range for all methods for SOF determination was 2-50 μg mL^-1 with coefficient of determination (R²) > 0.9999. Methods I, II & III were also applied for determination of SOF concentration in single dosage form. Their mean percentage recoveries were 100.35 ± 1.85, 99.97 ± 0.54 and 100.03 ± 0.49, for the three methods respectively. The proposed methods were validated according to international conference of harmonization (ICH) requirements and statistically compared to published reference methods. The ANOVA test confirmed that there is no significant differences between the proposed methods, and can be used for routine analysis of LED and SOF in commercial tablets. These developed methods were applied to estimate the average content and uniformity of dosage unit for LED/SOF combined dosage form and SOF single dosage form according to British pharmacopeia (BP) requirements.

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.

Development of a highly sensitive high-performance thin-layer chromatography method for the screening and simultaneous determination of sofosbuvir, daclatasvir, and ledipasvir in their pure forms and their different pharmaceutical formulations

The combination of sofosbuvir and daclatasvir or sofosbuvir and ledipasvir is now widely used as an ideal treatment for hepatitis C virus infection. For this purpose, a simple, sensitive, accurate, economic, and precise high-performance thin-layer chromatography was developed and validated for the determination of sofosbuvir, daclatasvir, and ledipasvir in their pure form as well as their different pharmaceutical products. The method used Merck high-performance thin-layer chromatography aluminum plates precoated with silica gel 60 F254 as a stationary phase and mobile phase consisting of methylene chloride/methanol/ethyl acetate/ammonia (25%) (6:1:4:1, v/v/v/v). This system was found to give compact symmetric peaks of sofosbuvir, daclatasvir, and ledipasvir with retardation factors of 0.27 ± 0.01, 0.50 ± 0.007, and 0.68 ± 0.008, respectively. The densitometric scanner was set at 275 nm using a deuterium lamp. The calibration curves were linear over the range of 100-3000 ng/spot for sofosbuvir, and daclatasvir, and range of 50-3000 ng/spot for ledipasvir. The detection limits were 22.5, 31.90, and 15.80 for sofosbuvir, daclatasvir, and ledipasvir. The quantitation limits were 67.50, 95.60, and 47.50 for sofosbuvir, daclatasvir, and ledipasvir. The proposed method was validated according to International Conference on Harmonization (ICH) guidelines and the results were acceptable.

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.

Spectroflurimetric estimation of the new antiviral agent ledipasvir in presence of sofosbuvir

A spectroflurimetric method has been developed and validated for the selective quantitative determination of ledipasvir in presence of sofosbuvir. In this method the native fluorescence of ledipasvir in ethanol at 405nm was measured after excitation at 340nm. The proposed method was validated according to ICH guidelines and show high sensitivity, accuracy and precision. Furthermore this method was successfully applied to the analysis of ledipasvir in pharmaceutical dosage form without interference from sofosbuvir and other additives and the results were statistically compared to a reported method and found no significant difference.