Bioequivalence study of two tablet formulations containing rimonabant 20 mg in healthy Indian subjects.

A randomized, two-treatment and two-way crossover study on twelve healthy Indian male subjects was conducted to assess the bioequivalence of two tablet formulations containing 20 mg of rimonabant (CAS 158681-13-1). Both of the formulations were administered orally as a single dose with a 45-day washout period between two dosing sessions. The content of rimonabant in plasma was determined by a validated HPLC method with UV detection. The formulations were compared using the parameters area under the plasma concentration-time curve (AUC(0-t)), area under the plasma concentration-time curve from zero to infinity (AUC(0-infinity)), peak plasma concentration (Cmax), and time to reach peak plasma concentration (tmax). The results of this investigation indicated that there were no statistically significant differences between the logarithmically transformed AUC(0-infinity) and Cmax values of the two preparations. The 90% confidence interval for the ratio of the logarithmically transformed AUC(0-t), AUC(0-infinity) and Cmax were within the bioequivalence limit of 0.8-1.25 and the relative bioavailability of the test formulation was 96.62% of that of the reference formulation. Thus, these findings clearly indicate that the two formulations are bioequivalent in terms of rate and extent of drug absorption.

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.

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.

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.

Pharmacokinetics and bioequivalence study of a fixed dose combination of rabeprazole and itopride in healthy Indian volunteers.

The aim of the present study was to compare the pharmacokinetics of rabeprazole (CAS 117976-89-3) and itopride (CAS 122898-67-3) after oral administration of a rabeprazole (20 mg)-itopride (150 mg) fixed dose combination (FDC) in healthy human volunteers. The bioequivalence of two formulations (test and reference) was determined in 12 healthy Indian male volunteers (age: 25.25 +/- 4.69 years; weight: 60.50 +/- 5.04 kg) in a randomized, single-dose, two-period, two-treatment crossover study. Both formulations were administered orally as a single dose, with the treatments separated by a washout period of 1 week. Rabeprazole and itopride plasma levels were determined by a validated HPLC method using UV detection. The formulations were compared using the pharmacokinetic parameters area under the plasma concentration-time curve (AUC(0-t)), area under the plasma concentration-time curve from zero to infinity (AUC(0-infinity)) and peak plasma concentration (Cmax). General linear model (GLM) procedures were used in which sources of variation were subject, treatment and period. The results indicated that there were no statistically significant differences (P > 0.05) between the logarithmically transformed AUC(0-infinity) and Cmax values between test and reference formulation. The 90% confidence interval for the ratio of the logarithmically transformed AUC(0-t), AUC(0-infinity) and Cmax were within the bioequivalence limits of 0.8-1.25 and the relative bioavailability of rabeprazole and itopride test and reference formulations was 98.24 and 93.65%, respectively.

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.

Development and validation of a high-performance liquid chromatographic method for bioanalytical application with rimonabant.

A simple and feasible high-performance liquid chromatographic method with UV detection was developed and validated for the quantification of rimonabant in human plasma. The chromatographic separation was carried out in a Hypersil BDS, C(18) column (250 mm x 4.6mm; 5 microm). The mobile phase was a mixture of 10 mM phosphate buffer and acetonitrile (30:70, v/v) at a flow rate of 1.0 ml/min. The UV detection was set at 220 nm. The extraction recovery of rimonabant in plasma at three quality control (QC) samples was ranged from 84.17% to 92.64%. The calibration curve was linear for the concentration range of 20-400 ng/ml with the correlation coefficient (r(2)) above 0.9921. The method was specific and sensitive with the limit of quantification of 20 ng/ml. The accuracy and precision values obtained from six different sets of QC samples analyzed in separate occasions ranged from 88.13% to 106.48% and 0.13% to 3.61%, respectively. In stability tests, rimonabant in human plasma was stable during storage and assay procedure. The method is very simple, sensitive and economical and the assay was applied to human plasma samples in a clinical (pharmacokinetic) study of rimonabant.

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.

Extended release dosage form of glipizide: development and validation of a level A in vitro-in vivo correlation.

Defining a quantitative and reliable relationship between in vitro drug release and in vivo absorption is highly desired for rational development, optimization, and evaluation of controlled-release dosage forms and manufacturing process. During the development of once daily extended-release (ER) tablet of glipizide, a predictive in vitro drug release method was designed and statistically evaluated using three formulations with varying release rates. In order to establish internally and externally validated level A in vitro-in vivo correlation (IVIVC), a total of three different ER formulations of glipizide were used to evaluate a linear IVIVC model based on the in vitro test method. For internal validation, a single-dose four-way cross over study (n=6) was performed using fast-, moderate-, and slow-releasing ER formulations and an immediate-release (IR) of glipizide as reference. In vitro release rate data were obtained for each formulation using the United States Pharmacopeia (USP) apparatus II, paddle stirrer at 50 and 100 rev. min(-1) in 0.1 M hydrochloric acid (HCl) and pH 6.8 phosphate buffer. The f(2) metric (similarity factor) was used to analyze the dissolution data. The formulations were compared using area under the plasma concentration-time curve, AUC(0-infinity), time to reach peak plasma concentration, T(max), and peak plasma concentration, C(max), while correlation was determined between in vitro release and in vivo absorption. A linear correlation model was developed using percent absorbed data versus percent dissolved from the three formulations. Predicted glipizide concentrations were obtained by convolution of the in vivo absorption rates. Prediction errors were estimated for C(max) and AUC(0-infinity) to determine the validity of the correlation. Apparatus II, pH 6.8 at 100 rev. min(-1) was found to be the most discriminating dissolution method. Linear regression analysis of the mean percentage of dose absorbed versus the mean percentage of in vitro release resulted in a significant correlation (r(2)>or=0.9) for the three formulations.

Bioequivalence study of two capsule formulations containing diacerein 50 mg in healthy human subjects.

This study presents the results of a two-way, two-period, two-treatment crossover investigation in 12 healthy Indian male subjects to assess the bioequivalence of two oral formulations containing 50 mg of diacerein (CAS 13739-02-1). Both formulations were administered orally as a single dose separated by a one-week washout period. The content of diacerein in plasma was determined by a validated HPLC method with UV detection. The formulations were compared using the parameters area under the plasma concentration-time curve (AUC(0-t)), area under the plasma concentration-time curve from zero to infinity (AUC(0-infinity)), peak plasma concentration (Cmax), and time to reach peak plasma concentration (tmax). The results of this study indicated that there were no statistically significant differences between the logarithmically transformed AUC(0-infinity) and Cmax, values of the two preparations. The 90% confidence interval for the ratio of the logarithmically transformed AUC(0-t), AUC(0-infinity) and Cmax were within the bioequivalence limit of 0.8-1.25 and the relative bioavailability of the test formulation was 96.63% of that of the reference formulation. Thus, these findings clearly indicate that the two formulations are bioequivalent in terms of rate and extent of drug absorption.

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.

Optimization of metformin HCl 500 mg sustained release matrix tablets using Artificial Neural Network (ANN) based on Multilayer Perceptrons (MLP) model.

The aim of the present study was to apply the simultaneous optimization method incorporating Artificial Neural Network (ANN) using Multi-layer Perceptron (MLP) model to the development of a metformin HCl 500 mg sustained release matrix tablets with an optimized in vitro release profile. The amounts of HPMC K15M and PVP K30 at three levels (-1, 0, +1) for each were selected as casual factors. In vitro dissolution time profiles at four different sampling times (1 h, 2 h, 4 h and 8 h) were chosen as output variables. 13 kinds of metformin matrix tablets were prepared according to a 2(3) factorial design (central composite) with five extra center points, and their dissolution tests were performed. Commercially available STATISTICA Neural Network software (Stat Soft, Inc., Tulsa, OK, U.S.A.) was used throughout the study. The training process of MLP was completed until a satisfactory value of root square mean (RSM) for the test data was obtained using feed forward back propagation method. The root mean square value for the trained network was 0.000097, which indicated that the optimal MLP model was reached. The optimal tablet formulation based on some predetermined release criteria predicted by MLP was 336 mg of HPMC K15M and 130 mg of PVP K30. Calculated difference (f(1) 2.19) and similarity (f(2) 89.79) factors indicated that there was no difference between predicted and experimentally observed drug release profiles for the optimal formulation. This work illustrates the potential for an artificial neural network with MLP, to assist in development of sustained release dosage forms.

Evaluation of the bioequivalence of two faropenem formulations in healthy Indian subjects.

This paper presents the results of a two-period, two-treatment, crossover study conducted in 12 Indian male volunteers under fasting conditions to assess the bioequivalence of two oral formulations (Reference and Test) containing 200 mg of faropenem (CAS 106560-14-9). Both of the formulations were administered orally as a single dose separated by a washout period of 1 week. The content of faropenem in plasma was determined by a validated HPLC method with UV detection. The formulations 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-infinity), peak plasma concentration (Cmax) and time to reach peak plasma concentration (tmax). The results Indicated that there were no statistically significant differences between the logarithmically transformed AUC0-infinity and Cmax values between the test and reference formulation. The 90% confidence interval for the ratio of the logarithmically transformed AUC0-t, AUC0-infinity and Cmax were within the bioequivalence limit of 0.8-1.25 and the relative bioavailability of the test formulation was 97.74% of that of the reference formulation.