📄 :Article 1

 

:Title

Applicability of LC-MS/MS to optimize derivatization of topiramate with FMOC-Cl using reacted/intact drug ratio

:Authors

Bahareh Mohammadi, Esmail Tammari, Sajad Fakhri, Gholamreza Bahrami

Journal: Journal of Chromatography B

Year: 2013

:Abstract
Topiramate is an antiepileptic agent, which is structurally different from the other anticonvulsants. The drug has no UV-Vis absorption or emits fluorescence. Thus for its analysis using high performance liquid chromatography (HPLC) with conventional UV or fluorescence detectors, the drug should be derivatized with a suitable reagent. In previous study using fluorenylmethyl chloroformate (FMOC-Cl) and HPLC coupled with fluorescence detector, we reported an analytical method for derivatization and analysis of the drug in human serum. In this method, several factors including time and temperature of the reaction, pH and concentration of the used buffer, ratio of organic phase in the medium and removal of the reagent excess by glycine should be optimized to obtain maximum yield of the product. In HPLC coupled with fluorescence detector, there is not any signal from intact topiramate and only the final product (FMOC-topiramate) is appeared. Thus to optimize the reaction conditions for obtaining the highest derived yield, intensity of the final product peak is considered as a criteria for progression of the reaction. In LC-MS/MS system however, both free and reacted topiramate are visible in observed spectra. In the present study reaction of the drug with FMOC-Cl was re-optimized using LC-MS/MS technique on the basis of reacted/free topiramate ratio as the new and more accurate index. The results showed that, ratio of organic/aqueous phase has a dominant effect on the reaction, the most efficient temperature is 70°C and the reaction is reversed following addition of the glycine.


تاریخ بروزرسانی : ۲۹ مهر ۱۴۰۵ ۱۲:۱۲

📄 :Article 2

 

:Title

Determination of atorvastatin in human serum by reversed-phase high-performance liquid chromatography with UV detection

Authors: Gholamreza Bahrami, Bahareh Mohammadi, Shahla Mirzaeei, Amir Kiani

Journal: Journal of Chromatography B

Year: 2005

:Abstract
A rapid and sensitive high-performance liquid chromatographic method was validated and described for determination of atorvastatin in human serum. Following liquid-liquid extraction of the drug and an internal standard (sodium diclofenac), chromatographic separation was accomplished using C18 analytical column with a mobile phase consisting of sodium phosphate buffer (0.05M, pH 4.0) and methanol (33:67, v/v). Atorvastatin and the internal standard were detected by ultraviolet absorbance at 247 nm. The average recoveries of the drug and internal standard were 95 and 80%, respectively. The lower limits of detection and quantification were 1 and 4 ng/ml, respectively, and the calibration curves were linear over a concentration range of 4-256 ng/ml of atorvastatin in human serum. The analysis performance was studied and the method was applied in a randomized cross-over bioequivalence study of two different atorvastatin preparations in 12 healthy volunteers.


تاریخ بروزرسانی : ۲۹ مهر ۱۴۰۵ ۱۲:۱۲

📄 :Article 3

 

:Title

Development and validation of a new HPLC-DAD method for quantification of sofosbuvir in human serum and its comparison with LC-MS/MS technique: Application to a bioequivalence study

Authors: Shahram Miraghaei, Bahareh Mohammadi, Atefeh Babaei, Samira Keshavarz, Gholamreza Bahrami

Journal: Journal of Chromatography B

Year: 2017

:Abstract
Although for many analyses tandem mass spectrometry (LC-MS/MS) systems have significant advantage over the high-performance liquid chromatography with diode array detection (HPLC-DAD) however, the HPLC methods are easier, cheaper and more available to perform. As no published method is available for quantitative HPLC analysis of sofosbuvir (SOF), an orally administered anti-hepatitis drug in human serum, this study was aimed to evaluate applicability of the HPLC technique to quantify sofosbuvir and comparison of the two methods for analytical performance. Following extraction of the drug and an internal standard (Hexobarbital), same chromatographic conditions were used for both the systems. After the chromatographic separation on a reverse phase C18 column using a mobile phase consisting of water (containing formic acid 0.5 mL/L) and acetonitrile (57:43; v/v) at a flow rate of 0.8 mL/min, the eluate was introduced into a DAD detector set at 261 nm, then passed through the mass spectrometry system in single ion monitoring mode (SIM). For UV and mass spectrometry detections the calibration curves were linear over a concentration range of 25-3200 and 10-3200 ng/mL, respectively and the linearity was over 0.998 for both the systems. Lower limit of quantification (LLOQ) for mass spectrometry and DAD detections were 10 and 25 ng/mL, respectively. In conclusion sensitivity of DAD detection is sufficient enough to determine concentrations down to 0.5% of Cmax which achieved in bioequivalence study of sofosbuvir and meet FDA requirements for these types of studies.


تاریخ بروزرسانی : ۲۹ مهر ۱۴۰۵ ۱۲:۱۳

📄 :Article 4

 

 

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

Authors: Mohammad Bagher Majnooni, Seid-Shahram Miraghaee, Samira Keshavarzi, Bahareh Mohammadi, Soraya Sajadimajd, Razieh Hatami, Gholamreza Bahrami

Journal: Journal of Pharmaceutical and Biomedical Analysis

Year: 2021

:Abstract
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 (IS, 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.


تاریخ بروزرسانی : ۲۹ مهر ۱۴۰۵ ۱۲:۱۳

📄 :Article 5

 

:Title

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

Authors: Mohammad Bagher Majnooni, Seid-Shahram Miraghaee, Samira Keshavarzi, Bahareh Mohammadi, Soraya Sajadimajd, Razieh Hatami, Gholamreza Bahrami

Journal: Journal of Pharmaceutical and Biomedical Analysis

Year: 2021

:Abstract
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 (IS, 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.


تاریخ بروزرسانی : ۲۹ مهر ۱۴۰۵ ۱۲:۱۳