Shabnam Nazir

A new HPLC method for the simultaneous determination of ascorbic acid and aminothiols in human plasma and erythrocytes using electrochemical detection

A new, simple, economical and validated high-performance liquid chromatography linked with electrochemical detector (HPLC-ECD) method has been developed and optimized for different experimental parameters to analyze the most common monothiols and disulfide (cystine, cysteine, homocysteine, methionine, reduced (GSH) and oxidized glutathione (GSSG)) and ascorbic acid present in human plasma and erythrocytes using dopamine as internal standard (IS). Complete separation of all the targets analytes and IS at 35°C on Discovery HS C18 RP column (250 mm × 4.6mm, 5 μm) was achieved using 0.05% TFA:methanol (97:3, v/v) as a mobile phase pumped at the rate of 0.6 ml min(-1) using electrochemical detector in DC mode at the detector potential of 900 mV. The limits of detection (3 S/N) and limits of quantification (10 S/N) of the studied compounds were evaluated using dilution method. The proposed method was validated according to standard guidelines and optimization of various experimental parameters and chromatographic conditions was carried out. The optimized and validated HPLC-ECD method was successfully applied for the determination of the abovementioned compounds in human plasma and erythrocytes. The method will be quite suitable for the determination of plasma and erythrocyte profile of ascorbic acid and aminothiols in oxidative stress and other basic research studies.

Simultaneous determination of rosuvastatin and atorvastatin in human serum using RP-HPLC/UV detection: Method development, validation and optimization of various experimental parameters

A novel, precise, accurate and rapid isocratic reversed-phase high performance liquid chromatographic/ultraviolet (RP-HPLC/UV) method was developed, optimized and validated for simultaneous determination of rosuvastatin and atorvastatin in human serum using naproxen sodium as an internal standard. Effect of different experimental parameters and various particulate columns on the analysis of these analytes was evaluated. The method showed adequate separation for rosuvastatin and atorvastatin and best resolution was achieved with Brownlee analytical C18 column (150×4.6 mm, 5 μm) using methanol-water (68:32, v/v; pH adjusted to 3.0 with trifluoroacetic acid) as a mobile phase at a flow rate of 1.5 ml/min and wavelength of 241 nm. The calibration curves were linear over the concentration ranges of 2.0-256 ng/ml for rosuvastatin and 3.0-384 ng/ml for atorvastatin. The lower limit of detection (LLOD) and lower limit of quantification (LLOQ) for rosuvastatin were 0.6 and 2.0 ng/ml while for atorvastatin were 1.0 and 3.0ng/ml, respectively. All the analytes were separated in less than 7.0 min. The proposed method could be applied for routine laboratory analysis of rosuvastatin and atorvastatin in human serum samples, pharmaceutical formulations, drug-drug interaction studies and pharmacokinetics studies.

OPTIMIZATION AND VALIDATION OF HPLC-UV METHOD FOR SIMULTANEOUS DETERMINATION OF OMEPRAZOLE AND ITS METABOLITES IN HUMAN PLASMA: EFFECTS OF VARIOUS EXPERIMENTAL CONDITIONS AND PARAMETERS

A simple and economical reversed phase HPLC-UV method was developed for omeprazole (OMP) and its two main metabolites, 5-Hydroxy omeprazole (5-OH-OMP) and omeprazole sulfone (OMP-S) in human plasma using pantoprazole as the internal standard. After optimization of various chromatographic conditions and experimental parameters, the method was validated according to standard guidelines. The separation of all the analytes was achieved on a Supelco C18 column using methanol and phosphate buffer (pH 7.2) in the ratio of (42:58, v/v) as the mobile phase in isocratic mode at a flow rate of 0.8 mL/min and wavelength of 302 nm, keeping column oven temperature at 45°C. Extraction of analytes from plasma was achieved through precipitation method followed by injecting a sample volume of 20 µL into the HPLC system. The limits of detection were 3, 1.5, and 1.3 ng/mL and limits of quantification were 10, 5, and 5 ng /mL for 5-0H-OMP, OMP-S, and OMP, respectively. The method was also successfully applied for the determination of S-isomer of omeprazole (esomeprazole) in human plasma.

Determination of Rosuvastatin and its Metabolite N-Desmethyl Rosuvastatin in Human Plasma by Liquid Chromatography–High Resolution Mass Spectrometry: Method Development, Validation, and Application to Pharmacokinetic Study

A novel liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for the determination of rosuvastatin (rosuva) and its metabolite N-desmethyl rosuvastatin (NDM-rosuva) in human plasma using atorvastatin as internal standard. The method was validated according to international guidelines. The analytical column used was HiChrom® C18 (150 × 3.0 mm, 3 µm; Reading, UK) and the mobile phase comprised of 0.1% formic acid in acetonitrile and 0.1% formic acid in water (70:30 v/v), pumped at 300 µL/min. The precipitation of plasma proteins and extraction of analytes were carried out by a simple one-step procedure using acetonitrile. The calibration curves were linear (r2 = 0.999) over the concentration range of 0.2–20 ng/mL for rosuva and 0.1–10 ng/mL for NDM-rosuva. The lower limits of detection and quantification for rosuva were 0.1 and 0.2 ng/mL, whereas for NDM-rosuva, these were 0.03 and 0.1 ng/mL, respectively. The intra- and inter-day precisions expressed as relative standard deviations (RSDs) were less than 2.5%. The average absolute recoveries of both rosuva and NDM-rosuva were greater than 95%. The method was successfully applied for the determination of rosuva and NDM-rosuva pharmacokinetics and drug–drug interaction studies.

Assessment of antibiotic self-medication practice among public in the northwestern region of Pakistan

Background Self-medication with antibiotics is a common practice, which may lead to the development of antimicrobial resistance (AMR)—a major health concern worldwide. The most common reason for the development of AMR is a lack of education and regulatory policies and the lack of community pharmacists. Objective To assess various factors that lead to self-medication with antibiotics, which might cause AMR and hinder effective healthcare. Methods A cross-sectional study was carried out using a predesigned questionnaire to collect data from 800 respondents. The respondents were selected by simple random sampling during November 2014 to January 2015 from different regions of Khyber Pakhtunkhwa (KPK), Pakistan. Only properly completed questionnaires were assessed for different variables. The collected data were analysed using SPSS V.16. Results 527 people completed and returned the questionnaire—a response rate of 66%. Self-medication with antibiotics was reported by 135 participants (26%), with a higher prevalence of men than women (48% vs 38%, respectively). The main reason for self-medication was previous experience with the same antibiotic (68%). The most commonly used antibiotics were amoxicillin-clavulanate (40%) and major indications for self-medication were sore throat (29%) and flu (24%). Of the 527 respondents, only 104 (20%) were aware of AMR. Conclusions This study is the first to evaluate self-medication with antibiotics in KPK, Pakistan. In view of the high prevalence of self-medication, introduction of a public health policy through drug regulatory authorities, public awareness programmes/campaigns, patient education about AMR and appropriate use of antibiotics are critically required. The role of community pharmacists needs to be strengthened.