Nagiat T Hwisa

Simultaneous determination of ezetimibe and simvastatin in rat plasma by stable-isotope dilution LC-ESI–MS/MS and its application to a pharmacokinetic study

A simple, sensitive and specific liquid chromatography–tandem mass spectrometry method was developed for simultaneous quantification of ezetimibe and simvastatin in rat plasma. The deuterium isotopes: ezetimibe d4 and simvastatin d6 were used as internal standards for ezetimibe and simvastatin, respectively. MS/MS detection involved a switch of electron spray ionization mode from negative to positive at retention time 3.01 min. Samples were extracted from plasma by liquid–liquid extraction using tertiary butyl methyl ether. Chromatographic separation was achieved with Agilent Eclipse XBD-C18 column using mobile phase that consisted of a mixture of ammonium acetate (pH4.5; 10 mM)–acetonitrile (25:75 v/v). The method was linear and validated over the concentration range of 0.2–40.0 ng/mL for simvastatin and 0.05–15.0 ng/mL for ezetimibe. The transitions selected were m/z 408.3→271.1 and m/z 412.0→275.10 for ezetimibe and ezetimibe d4, and m/z 419.30→285.20 and m/z 425.40→199.20 for simvastatin and simvastatin d6. Intra- and inter-batch precisions for ezetimibe were 1.6–14.8% and 2.1–13.4%; and for simvastatin 0.94–9.56% and 0.79–12%, respectively. The proposed method was sensitive, selective, precise and accurate for the quantification of ezetimibe and simvastatin simultaneously in rat plasma. The method was successfully applied to a pharmacokinetic study by oral co-administration of ezetimibe and simvastatin in SD rats.

Simultaneous Quantification of Mesalamine and Its Metabolite N-Acetyl Mesalamine in Human Plasma by LC-MS/MS and Its Application to a Bioequivalence Study

Liquid chromatography–tandem mass spectrometry (LC–MS/MS) was used for simultaneous quantification of mesalamine and its metabolite N-acetyl mesalamine in human plasma with N-acetyl mesalamine D3 as an internal standard (IS). Chromatographic separation was performed on a Thermo, HyPURITY C18 (150 x 4.6 mm, 5 m) column with an isocratic mobile phase composed of 10 mM ammonium Original Research Article British Journal of Pharmaceutical Research, 4(13): 1568-1590, 2014 1569 acetate and methanol in the ratio of 85:15 (%v/v), at the flowrate of 0.6 mL/min. The drug, metabolite and internal standard were extracted by liquid-liquid extraction. The method was validated over a linear concentration range of 2-1500 ng/mL for mesalamine and 102000 ng/ml for N-acetyl mesalamine, which demonstrated intra and inter-day precision ranging from 1.60 to 8.63% and 2.14 to 8.67% for mesalamine and 0.99 to 5.67% and 1.72 to 4.89% for N-acetyl mesalamine respectively. Similarly, the intraand inter-day accuracy varied from 102.70 to 105.48% and 100.64 to 103.87% for mesalamine, 99.64 to 106.22% and 100.71 to 104.27% for N-acetyl mesalamine respectively. Both analytes were found to be stable throughout freeze–thawing cycles, bench top and postoperative stability studies. The method was successfully applied to support a bioequivalance study of healthy subjects.

An Experimental Design Approach for Impurity Profiling of Valacyclovir-Related Products by RP-HPLC

Abstract Impurity profiling has become an important phase of pharmaceutical research where both spectroscopic and chromatographic methods find applications. The analytical methodology needs to be very sensitive, specific, and precise which will separate and determine the impurity of interest at the 0.1% level. Current research reports a validated RP-HPLC method to detect and separate valacyclovir-related impurities (Imp-E and Imp-G) using the Box-Behnken design approach of response surface methodology. A gradient mobile phase (buffer: acetonitrile as mobile phase A and acetonitrile: methanol as mobile phase B) was used. Linearity was found in the concentration range of 50–150 μg/mL. The mean recovery of impurities was 99.9% and 103.2%, respectively. The %RSD for the peak areas of Imp-E and Imp-G were 0.9 and 0.1, respectively. No blank interferences at the retention times of the impurities suggest the specificity of the method. The LOD values were 0.0024 μg/mL for Imp-E and 0.04 μg/mL for Imp-G and the LOQ values were obtained as 0.0082 μg/mL and 0.136 μg/mL, respectively, for the impurities. The S/N ratios in both cases were within the specification limits. Proper peak shapes and satisfactory resolution with good retention times suggested the suitability of the method for impurity profiling of valacyclovir-related drug substances.

Bioanalytical method development and validation of milnacipran in rat plasma by LC-MS/MS detection and its application to a pharmacokinetic study

A simple, sensitive and specific liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for the quantification of milnacipran (MC) in rat plasma by using the liquid–liquid extraction method. Milnacipran-d10 (MCD10) was used as an internal standard (IS). Chromatographic separation was achieved on Zorbax SB-CN (4.6 mm×75 mm, 3.5 µm) column with an isocratic mobile phase composed of 10 mM ammonium acetate (pH 4.0) and methanol in the ratio of 25:75(v/v), at a flow-rate of 0.7 mL/min. MC and MCD10 were detected with proton adducts at m/z 247.2→230.3 and m/z 257.2→240.4 in multiple reaction monitoring (MRM) positive mode respectively. The method was validated over a linear concentration range of 1.00–400.00 ng/mL with a correlation coefficient (r2)≥0.9850. This method demonstrated intra- and inter-day precision within 5.40–10.85% and 4.40–8.29% and accuracy within 97.00–104.20% and 101.64–106.23%. MC was found to be stable throughout three freeze–thaw cycles, bench top and postoperative stability studies. This method was successfully applied to a pharmacokinetic study of rats through i.v. administration.

Pandemic influenza A (H1N1) vaccination among libyan health care personnel: A cross-sectional retrospective study

Context: Vaccination rate among health-care personnels (HCPs) are not promising notwithstanding the World Health Organization campaigns over three decades resulting in compromising patient safety. The H1N1 virus, which caused a world-wide pandemic earlier has now transformed into a seasonal flu virus. Aims: The aim of this study was to analyze the incidence of 2009-10 pandemic influenza A (H1N1) vaccination among Libyan HCPs in four hospitals of Al-Zawia, Libya. Materials and Methods: A questionnaire, which listed eight sections of parameters distributed among 310 HCPs to assess the vaccination rate and resulting adverse effects. Statistical Analysis: The data were analyzed using descriptive statistics, Pearsons χ2-test and Students t-test where appropriate. Results: The overall pandemic A (H1N1) vaccination among all HCPs was only 107 (39.9%) out of 268 respondents. The distribution of respondents based on physicians, other staff and sex were found significant (P < 0.05). The common barriers of H1N1 vaccination being lack of awareness fear of adverse effects, allergies and religious beliefs. The major adverse effect observed was erythema in 95.56% of physicians and 87.1% in other staff. About 2% of HCPs have reported arthralgia. No significant differences existed between the responses of general variables and adverse effects. The glycoprotein 120 and squalene were found responsible for the reported adverse effects. 37 (82.22%) vaccinated medical HCPs have advised their patients to get vaccinated. Conclusions: Due to recurrence of H1N1 influenza in recent times, vaccination campaigns should be promoted immediately to address the knowledge gap of HCPs for intervention by regulatory and health organizations in Libya. The health belief model could be applied to improve vaccination among HCPs.