Anirbandeep Bose

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.

Microwave assisted synthesis of acrylamide grafted locust bean gum and its application in drug delivery.

Acrylamide grafted copolymer of locust bean gum was prepared by microwave irradiation using ceric ammonium nitrate as redox initiator. The grafting process was optimized in terms of irradiation time, amount of initiator and acrylamide by using constant amount of native locust bean gum. The grafted gum was characterized by Fourier transform infrared spectroscopy (FT-IR), (13)C nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), X-ray diffraction study (XRD), differential scanning calorimetry (DSC), elemental analysis, contact angle, viscosity, molecular weight, swelling and biodegradability studies. The grafted gum was found to be biodegradable and non-toxic. It was further used to prepare controlled-release matrix tablet of buflomedil hydrochloride. The in vitro release profile of the tablet showed the rate controlling property of acrylamide grafted locust bean gum was similar to that of hydroxypropyl methylcellulose (HPMC-K15M).

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.

Oral 5-fluorouracil colon-specific delivery through in vivo pellet coating for colon cancer and aberrant crypt foci treatment.

In situ coating of 5-fluorouracil pellets by ethylcellulose and pectin powder mixture (8:3 weight ratio) in capsule at simulated gastrointestinal media provides colon-specific drug release in vitro. This study probes into pharmacodynamic and pharmacokinetic profiles of intra-capsular pellets coated in vivo in rats with reference to their site-specific drug release outcomes. The pellets were prepared by extrusion-spheronization technique. In vitro drug content, drug release, in vivo pharmacokinetics, local colonic drug content, tumor, aberrant crypt foci, systemic hematology and clinical chemistry profiles of coated and uncoated pellets were examined against unprocessed drug. In vivo pellet coating led to reduced drug bioavailability and enhanced drug accumulation at colon (179.13 μg 5-FU/g rat colon content vs 4.66 μg/g of conventional in vitro film-coated pellets at 15 mg/kg dose). The in vivo coated pellets reduced tumor number and size, through reforming tubular epithelium with basement membrane and restricting expression of cancer from adenoma to adenocarcinoma. Unlike uncoated pellets and unprocessed drug, the coated pellets eliminated aberrant crypt foci which represented a putative preneoplastic lesion in colon cancer. They did not inflict additional systemic toxicity. In vivo pellet coating to orally target 5-fluorouracil delivery at cancerous colon is a feasible therapeutic treatment approach.

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.

Development and validation of an HPLC method for analysis of etoricoxib in human plasma

A simple high-performance liquid chromatographic method for the determination of etoricoxib in human plasma has been developed. An aliquot quantity of 1 ml plasma sample was taken and 10 ml internal standard was added and mixed. Saturated borate solution of 0.3 ml was added to it and mixed for 1 minute followed by liquid-liquid extraction with ethyl acetate. Organic layer was separated and evaporated to dryness under nitrogen atmosphere at low temperature (below 50°). Residue was reconstituted with 150 µl of mobile phase. During the whole procedure the samples were protected from light. The assay was performed on Hypersil BDS, C18 (150×4.6 mm, 5 m particle size) column, using 10 milimol ammonium acetate buffer:acetonitrile = 65:35 v/v as mobile phase with ultra violet detection at 235 nm. Lower limit of detection was 10 ng/ml and lower limit of quantitation was 20 ng/ml. Maximum between-run precision was 7.94%. Mean extraction recovery was found to be 79.53 to 85.70%. Stability study showed that after three freeze-thaw cycles the loss of three quality control samples were less than 10%. Samples were stable at room temperature for 12 h and at -20° for 3 months. Before injecting onto HPLC system, the processed samples were stable for at least 8 h. The method was used to perform bioequivalence study in human.

Coatless alginate pellets as sustained-release drug carrier for inflammatory bowel disease treatment

Conventional alginate pellets underwent rapid drug dissolution and failed to exert colon targeting unless subjected to complex coating. This study designed coatless delayed-release oral colon-specific alginate pellets for ulcerative colitis treatment. Alginate pellets, formulated with water-insoluble ethylcellulose and various calcium salts, were prepared using solvent-free melt pelletization technique which prevented reaction between processing materials during agglomeration and allowed reaction to initiate only in dissolution. Combination of acid-soluble calcium carbonate and highly water-soluble calcium acetate did not impart colon-specific characteristics to pellets due to pore formation in fragmented matrices. Combination of moderately water-soluble calcium phosphate and calcium acetate delayed drug release due to rapid alginate crosslinking by soluble calcium from acetate salt followed by sustaining alginate crosslinking by calcium phosphate. The use of 1:3 ethylcellulose-to-alginate enhanced the sustained drug release attribute. The ethylcellulose was able to maintain the pellet integrity without calcium acetate. Using hydrophobic prednisolone as therapeutic, hydrophilic alginate pellets formulated with hydrophobic ethylcellulose and moderately polar calcium phosphate exhibited colon-specific in vitro drug release and in vivo anti-inflammatory action. Coatless oral colon-specific alginate pellets can be designed through optimal formulation with melt pelletization as the processing technology.

Convolution and validation of in vitro–in vivo correlation of water-insoluble sustained-release drug (domperidone) by first-order pharmacokinetic one-compartmental model fitting equation

The experimental study presents a brief and comprehensive perspective on the methods of developing a Level A in vitro–in vivo correlation (IVIVC) for extended oral dosage forms of water-insoluble drug domperidone. The study also evaluates the validity and predictability of in vitro–in vivo correlation using the convolution technique by one-compartmental first-order kinetic equation. The IVIVC can be substituted as a surrogate for in vivo bioavailability study for the documentation of bioequivalence studies as mandatory from any regulatory authorities. The in vitro drug release studies for different formulations (fast, moderate, slow) were conducted in different dissolution mediums. The f (2) metric (similarity factor) was used to analyze the dissolution data for determination of the most discriminating dissolution method. The in vivo pharmacokinetics parameters of all the formulations were determined by using liquid chromatography mass spectrometry (LC/MS) methods. The absorption rate constant and percentage of absorption of drugs at different time intervals were calculated by using data convolution. In vitro drug release and in vivo absorption correlation were found to be a linear correlation model, which was developed by using percent absorbed drug release versus percent drug dissolved from the three formulations. Internal and external validation was performed to validate the IVIVC. Predicted domperidone concentrations were obtained by convolution technique using first-order one-compartmental fitting equation. Prediction errors estimated for C (max) and AUC (0–infinity) were found to be within the limit.