Uday S Chakrabarty

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.

Bioequivalence study of a fixed dose combination tablet containing rabeprazole and diclofenac sodium in healthy Indian subjects

The pharmacokinetics of rabeprazole (CAS 117976-89-3) and diclofenac sodium (CAS 15307-79-6) has been extensively evaluated in adult human volunteers individually after oral administration of tablet formulation. However, no published data is available regarding the combined pharmacokinetics and bioavailability of this particular fixed dose combination. In light of the above, a clinical study was designed to evaluate the bioequivalence of two fixed dose combination (FDC) products (reference and test) of two manufacturers containing rabeprazole 20 mg and diclofenac sodium 100 mg slow release (SR) tablet in healthy Indian male volunteers. Each subject received a test FDC and a reference FDC in a randomized, single dose, fasting state, two period, and crossover study design with a one-week washout period between the doses. Extraction of the drugs from the plasma was carried out by the precipitation method. Analysis of rabeprazole and diclofenac sodium from plasma samples was done by a simple and sensitive HPLC method using a UV detector. An analysis of variance was performed on the pharmacokinetic parameters of Cmax, tmax, AUC(0-t), and AUC(0-infinity), using general linear model (GLM) procedures in which sources of variation were subject, formulation and period. 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 logarithmically transformed AUC(0-t), AUC(0-infinity) and Cmax were within the bioequivalence limit of 0.80-1.25 and the relative bioavailability of rabeprazole and diclofenac sodium were found to be 98.6% and 98.9% respectively in the test product. Thus, these findings clearly indicated that the two products are bioequivalent in terms of rate and extent of drug absorption.

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.

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.

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.

Bioequivalence study of levofloxacin tablets in healthy Indian volunteers using HPLC.

An improved HPLC method was developed and validated for the determination of concentration of levofloxacin (CAS 100986-85-4) in human plasma. This paper is an attempt to compare the bioavailability of two levofloxacin tablet formulations (reference and test) containing 500 mg of levofloxacin. Both the formulations were administered orally as a single dose, separated by a washout period of 1 week. The HPLC method was validated by examining the precision and accuracy for the inter-day and intra-day runs in a linear concentration range of 0.10-10.00 microg/ml. Bioequivalence of two formulations were determined in 12 healthy, Indian, male volunteers in a single-dose, two-period, two-sequence, two-treatment crossover study. The content of levofloxacin in plasma was determined using HPLC with UV detection. The formulations were compared using the following pharmacokinetic parameters: area under the plasma concentration-time curve (AUC(o-t)), area under the plasma concentration-time curve from zero to infinity (AUC(o-infinity)), peak plasma concentration (C(max)), and time to reach peak plasma concentration (t(max)). The results indicated that there were no statistically significant differences (P > 0.05) between the logarithmically transformed AUC(o-infinity), and C(max) values of the test and reference formulations. The 90% confidence interval for the ratio of the logarithmically transformed AUC(o-t), AUC(o-infinity) and C(max) were within the bioequivalence limit of 0.8-1.25 and the relative bioavailability of the test formulation was 99.98% of that of the reference formulation.

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.