Amlan Kanti Sarkar

Simultaneous determination of metoprolol succinate and amlodipine besylate in human plasma by liquid chromatography-tandem mass spectrometry method and its application in bioequivalence study

A simple, sensitive and specific liquid chromatography-tandem mass spectrometry method was developed and validated for quantification of metoprolol succinate (MPS) and amlodipine besylate (AM) using hydrochlorothiazide (HCTZ) as IS in human plasma. Both the drugs were extracted by simple liquid-liquid extraction with chloroform. The chromatographic separation was performed on a reversed-phase peerless basic C18 column with a mobile phase of methanol-water containing 0.5% formic acid (8:2, v/v). The protonated analyte was quantitated in positive ionization by multiple reaction monitoring with a mass spectrometer. The method was validated over the concentration range of 1-100 ng/ml for MPS and 1-15 ng/ml AM in human plasma. The MRM transition of m/z 268.10-103.10, m/z 409.10-334.20 and m/z 296.00-205.10 were used to measure MPS, AM and HCTZ (IS), respectively. This method was successfully applied to the pharmacokinetic study of fixed dose combination (FDC) of MPS and AM formulation product after an oral administration to Indian healthy human volunteers.

Determination of gemifloxacin in different tissues of rat after oral dosing of gemifloxacin mesylate by LC–MS/MS and its application in drug tissue distribution study

A simple, sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to evaluate the accumulation of gemifloxacin in different tissues of Wister albino rat. The analytical method consists of the homogenization of tissues followed by simple liquid-liquid extraction and determination of gemifloxacin by an LC-MS/MS. The analyte was separated on a Peerless basic C(18) column (33 mm x 4.6 mm, 3 microm) with an isocratic mobile phase of methanol-water containing formic acid (1.0%, v/v) (9:1, v/v) at a flow rate of 0.6 ml/min. The MS/MS detection was carried out by monitoring the fragmentation of m/z 390.100-->372.100 for gemifloxacin and m/z 332.100-->314.200 for ciprofloxacin (internal standard; IS) on a triple quadrupole mass spectrometer. The validated method was accurate, precise and rugged with good linearity in all tissue homogenates. The accuracy and precision value obtained from six different sets of quality control samples of all tissues and serum analyzed in separate occasions within 91.833-102.283% and 0.897-5.291%, respectively. The method has been successfully applied to tissue distribution studies of gemifloxacin. The present study demonstrates that the highest tissue concentration of gemifloxacin was obtained in lung (11.891 ng/g), followed by liver (10.110 ng/g), kidney (10.095 ng/g), heart (4.251 ng/g), testis (3.750 ng/g), stomach (3.182 ng/g), adipose tissue (1.116 ng/g) and brain (0.982 ng/ml) in 3h after multiple oral dosing of 200mg gemifloxacin mesylate for 7 days. This method may also be used for gemifloxacin tissue distribution modeling study in rat tissues and antibiotic residue analyses in other animal tissues.

Determination of ranolazine in human plasma by LC-MS/MS and its application in bioequivalence study

A simple, sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for quantification of ranolazine in human plasma. The analytical method consists in the precipitation of plasma sample with methanol, followed by the determination of ranolazine by an LC-MS/MS. The analyte was separated on a Peerless Cyano column (33 mm x 4.6 mm, 3 microm) an isocratic mobile phase of methanol-water containing formic acid (1.0%, v/v) (65:35, v/v) at a flow rate of 1.0 ml/min. Protonated ions formed by a turbo ionspray in positive mode were used to detect analyte and internal standard (IS). The MS/MS detection was made by monitoring the fragmentation of m/z 428.20-->279.50 for ranolazine and m/z 448.30-->285.20 for internal standard on a triple quadrupole mass spectrometer. The method was validated over the concentration range of 5-2000 ng/ml for ranolazine in human plasma with correlation coefficient of 0.9937 (S.D.: +/-0.00367, range: 0.9895-0.9963). The accuracy and precision values obtained from six different sets of quality control samples analyzed in separate occasions ranged from 94.53 to 117.86 and 0.14% to 4.56%, respectively. Mean extraction recovery was 82.36-94.25% for three quality control (QC) samples and 88.37% for IS. Plasma samples were stable for three freeze-thaw cycles, or 24h ambient storage, or 1 and 3 months storage at -20 degrees C. Processed samples (ready for injection) were stable up to 72 h at autosampler (4 degrees C). The developed method was successfully applied for analyzing ranolazine in plasma samples for a bioequivalence study with 12 healthy volunteers.

Development and validation of an LC-ESI-MS/MS method for simultaneous quantitation of olmesartan and pioglitazone in rat plasma and its pharmacokinetic application

A simple, high-throughput and specific high-performance liquid chromatography tandem mass spectrometry method has been developed and validated according to the FDA guidelines for simultaneous quantification of olmesartan and pioglitazone in rat plasma. The bioanalytical method consists of liquid-liquid extraction and quantitation by triple quadrupole mass spectrometry using electrospray ionization technique, operating in multiple reaction monitoring and positive ion modes. The compounds were eluted isocratically on a C(18) column with a mobile phase consisting of a mixture of methanol and water (containing 0.5% formic acid) in a ratio of 9:1. The response to olmesartan and pioglitazone was linear over the range 0.01-10 µg/mL. The validation results demonstrated that the method had satisfactory precision and accuracy across the calibration range. Intra- and inter-day precisions ranged from 0.66 to 3.32 and from 0.94 to 2.93% (%CV), respectively. The accuracy determined at three quality control levels was within 91.27-107.28%. There was no evidence of instability of the analytes in rat plasma following the stability studies. The method proved highly reproducible and sensitive and was successfully applied in a pharmacokinetic study after single dose oral administration of olmesartan and pioglitazone to the rat.

Evaluation of bioequivalence of two formulations containing 100 milligrams of aceclofenac

ABSTRACT The bioequivalence of two oral formulations containing aceclofenac 100 mg was determined in 24 healthy Indian male volunteers. The study was designed as a single dose, fasting, two-period two-sequence crossover study with a washout period of 1 week. The content of aceclofenac in plasma was determined by a validated HPLC method with UV detection. The preparations were compared using the parameters area under the plasma concentration–time curve (AUC0–t), area under the plasma concentration–time curve from zero to infinity (AUC0–∞), peak plasma concentration (Cmax), and time to reach peak plasma concentration (tmax). No statistically significant difference was observed between the logarithmic transformed AUC0–∞ and Cmax values of the two preparations. The 90% confidence interval for the ratio of the logarithmic transformed AUC0–t, AUC0–∞, and Cmax were within the bioequivalence limit of 0.80–1.25.

Twenty-eight days repeated oral dose toxicity study of gemifloxacin in Wistar albino rats

The purpose of this study was to investigate the potential toxicity of gemifloxacin by 28-day repeated oral dose in Wistar albino rats. The test article, was administered daily by gavage to male and female rats at dose levels of 0, 50, 100, 200 mg/kg/day. At the end of treatment period, 12 rats/sex/group was sacrificed, while six extra rats/sex in the vehicle control and highest dose groups sacrificed after 14 days recovery period. During the treatment and recovery periods, clinical signs, mortality, body weights, food and water consumption, ophthalmoscopy, urinalysis, phototoxicity, hematology, serum biochemistry, synovial fluid biochemistry, electrocardiogram (ECG), gross findings, organ weights, microscopic examination of synovial fluid, and histopathology were examined. Hematological and serum biochemical investigations revealed a dose-dependent increase in the total white blood cell (WBC), total bilirubin (T-BIL), glucose (GLU), alanine aminotransferase (ALT) and significant decreases in total protein (TP) were observed in both sexes at the same dose, at the end of treatment period, but the levels returned toward normal during the recovery period. Histopathology of talar joint showed that erosion of the articular surface of that joint in both sexes at the end of treatment period at the dose level of 200 mg/kg/day. Degenerative changes in tendinocytes were observed in Achilles tendon of both sexes at the high dose level at the end of treatment period. In histopathological study shows partial effacement of liver architecture and focal ulceration in gastric mucosa at the high dose level at the end of treatment period. Based on these results, it was concluded that 28 days repeated oral dose of gemifloxacin caused increases in the liver weight, WBC count, T-BIL, glucose level, ALT, decreasing the TP, cause chronic hepatitis and acute gastritis, erosion of the articular surface of joint and histopathologic changes in Achilles tendon in rats at the dose level of 200 mg/kg/day.

Retracted: Convulsant activity and pharmacokinetic–pharmacodynamic modeling of the electroencephalogram effect of gemifloxacin in rats

A pharmacokinetic-pharmacodynamic (PK-PD) modeling approach was used to investigate the epileptogenic activity of gemifloxacin as a representative antibiotic with concentration-dependent antimicrobial activity. Rats received an intravenous infusion of gemifloxacin at a rate of 4 mg kg of body weight(-1) min(-1) over 50 min. Blood samples were collected for drug assay, and an electroencephalogram (EEG) was recorded during infusion and postinfusion. An important delay was observed between concentrations of gemifloxacin in plasma and the EEG effect; this effect was accompanied by tremors and partial seizures. Indirect effect models failed to describe these data, which were successfully fitted by using an effect compartment model with a spline function to describe the relationship between effect and concentration at the effect site. The robustness of the PK-PD model was then assessed by keeping the dose constant but increasing the duration of infusion to 100 and 200 min. Although this was accompanied by PK modifications, PD parameters did not vary significantly, and the PK-PD model still applied. In conclusion, the successful PK-PD modeling of the gemifloxacin EEG effect in rats should be considered to predict and reduce the epileptogenic risk associated with this antibiotic as a representative fluoroquinolone.

Development of RP-HPLC for analysis of human insulin

The objective of the present work is to develop a simple and sensitive method for analysis of human insulin injection by using reverse-phase high performance liquid chromatography technique. A reverse-phase high performance liquid chromatography method with UV-detection at room temperature has been developed for the analysis of insulin from formulation. Hypersil BDS C-18 was used as stationary phase, and mobile phase consisted of 60 volume of 1 mmol sodium sulphate and 0.2% triethylamine in water, pH 3.2 adjusted by phosphoric acid, and 40 volume of acetonitrile. The eluent was monitored with a UV detector set at 214 nm with a flow rate of 1 ml/min, and sample size of 20 µl were carried out at room temperature all over the study. The method produced linear response over the concentration range of 10-100 µg/ml, with a mean recovery of 97 ± 0.31% as well as average intra- and inter-day variations of 1.35 and 5.13% respectively. The limits of detection and quantitation of the method were 0.25 and 0.75 µg/ml respectively. Considering the analysis specifications, the system is suitable for direct analysis of routine formulations and stability studies.

A rapid LC-ESI-MS/MS method for the quantitation of choline, an active metabolite of citicoline: Application to in vivo pharmacokinetic and bioequivalence study in Indian healthy male volunteers.

A rapid, simple, and sensitive high performance liquid chromatography-tandem mass spectrometry method (LC-ESI-MS/MS) was developed and validated for the determination and pharmacokinetic investigation of choline (CL), active metabolite of citicoline in human plasma using metformin (MF) as IS. The chromatographic separation was performed on a reversed-phase Phenomenx Gemini C18 column with a mobile phase of methanol:water (containing 10mM ammonium formate) (9:1, v/v). The calibration curves were linear over the range of 0.05-5μg/ml. The validated LC-ESI-MS/MS method was successfully applied for the evaluation of pharmacokinetic parameters and bioequivalence study of test and reference control release (CR) tablet preparation of citicoline 1000mg after a single oral administration to all 12 healthy male volunteers.

Comparative Bioavailability Study of Amisulpride Tablets in Healthy Indian Volunteers

An improved HPLC method was developed and validated for the determination of concentration of amisulpride (CAS 71675-85-9) in human plasma, an attempt to compare the bioavailability of two amisulpride tablet formulations (reference and test) containing 200 mg of amisulpride. Both the formulations were administered orally as a single dose, separated by washout period of 1 week. This HPLC method validated by examining the precision and accuracy for the inter-day and intra-day runs in a linear concentration range of 50-1200 ng/ml. Bioequivalence of two formulation were determined on 12 healthy Indian male volunteer in a single-dose, two-period, two-sequence, two-treatment crossover study. The content of amisulpride in plasma was determined by a validated HPLC method with UV detection. The formulations were compared using the parameters like area under the plasma concentration-time curve (AUC0-t), area under the plasma concentration-time curve from zero to infinity (AUC0-infinity), peak plasma concentration (Cmax), and time to reach peak plasma concentration (tmax). The results indicated that there were no statistically significant differences (P > 0.05) between the logarithmic transformed AUC0-infinity and Cmax, values, between test and reference formulation. The 90% confidence interval for the ratio of the logarithmic transformed AUC0-t, AUC0-infinity, and Cmax were within the bioequivalence limit of 0.8-1.25 and the relative bioavailability of test formulation was 96.82% to that of reference formulation.