Comparative bioequivalence studies of tramadol hydrochloride sustained-release 200 mg tablets.

BACKGROUND: Tramadol hydrochloride is available as 50 mg immediate-release (IR) and 100 mg, 200 mg, and 300 mg sustained-release (SR) tablets. The recommended dose of tramadol is 50-100 mg IR tablets every 4-6 hours. The tramadol SR 200 mg tablet is a better therapeutic option, with a reduced frequency of dosing, and improved patient compliance and quality of life. The present study evaluated the bioequivalence of a generic tramadol SR 200 mg tablet. METHODS: A comparative in vitro dissolution study was performed on the test and reference products, followed by two separate single-dose bioequivalence studies under fasting and fed conditions and one multiple-dose bioequivalence study under fasting conditions. These bioequivalence studies were conducted in healthy human subjects using an open-label, randomized, two-treatment, two-period, two-sequence, crossover design. The oral administration of the test and reference products was done on day 1 for both the single-dose studies and on days 1-5 for the multiple-dose study in each study period as per the randomization code. Serial blood samples were collected at predefined time points in all the studies. Analysis of plasma concentrations of tramadol and O-desmethyltramadol (the M1 metabolite) was done by a validated liquid chromatography-mass spectrometry analytical method. The standard acceptance criterion of bioequivalence was applied on log-transformed pharmacokinetic parameters for tramadol and its M1 metabolite. RESULTS: The ratios for geometric least-square means and 90% confidence intervals were within the acceptance range of 80%-125% for log-transformed primary pharmacokinetic parameters for tramadol and its M1 metabolite in all the three studies. CONCLUSION: The test product is bioequivalent to the reference product in terms of rate and extent of absorption, as evident from the single-dose and multiple-dose studies. Both the treatments were well tolerated.

A simple, selective and rapid validated method for estimation of anastrazole in human plasma by liquid chromatography-tandem mass spectrometry and its application to bioequivalence study.

A rapid, simple and specific method for estimation of anastrazole in human plasma was validated using letrozole as internal standard. The analyte and internal standard were extracted from plasma using simple solid-phase extraction. The compound were separated on a reverse-phase column with an isocratic mobile phase consisting of 0.1% formic acid in water and acetonitrile (12 : 88, v/v) and detected by tandem mass spectrometry in positive ion mode. The ion transitions recorded in multiple reaction monitoring mode were m/z 294.1 --> 225.1 for anastrazole and m/z 286.1 --> 217.1 for internal standard. Linearity in plasma was observed over the concentration range 0.3-30 ng/mL for anastrazole. The mean recovery for anastrazole was 83.7% with a lower limit of quantification of 0.3 ng/mL. The coefficient of variation of the assay was less than 6.8% and the accuracy was 96.1-102.2%. The validated method was applied to a bioequivalence study of 1 mg anastrazole tablet in healthy human volunteers.

Validated LC-MS/MS method for determination of Alverine and one of its hydroxy metabolites in human plasma along with its application to a bioequivalence study.

The present research work involves a first of its kind rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method developed and validated for simultaneous analysis of Alverine (ALV) and one of its hydroxy metabolites, para hydroxy Alverine (PHA) in human plasma. The analytes were extracted from the matrix using a simple solid-phase extraction procedure. Mebeverine was used as the internal standard for both analytes. A Kromasil C8 column provided chromatographic separation of analytes followed by detection with mass spectrometry. The method involves simple isocratic chromatography conditions and mass spectrometric detection in the positive ionization mode using an API 5000 MS/MS system. The proposed method has been validated with a linear range of 100-10,000 pg/mL for both ALV and PHA. The interrun and intrarun precision values are within 6.3%, 3.7% for ALV and 6.3%, 3.2% for PHA at LOQ levels. The intrarun accuracy in terms of % RE was within the range of -7.0% to -0.1% and -8.1% to -1.7% for ALV and PHA, respectively whereas the interrun accuracy was within the range of -5.1% to -0.5% for ALV and -8.6% to 0.4% for PHA, respectively. The overall recoveries for ALV and PHA were 83.5% and 86.2% respectively. Total elution time was about 4 min which allowed quantitation of more than 150 plasma samples per day. This validated method was used successfully for analysis of real samples from a bioequivalence study.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous determination of tenofovir and emtricitabine in human plasma and its application to a bioequivalence study.

A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for simultaneous quantification of Tenofovir (TEN) and Emtricitabine (EMT) in human plasma using Chromolith Speed Rod RP18. The mass transition ion-pair has been followed as m/z 288.10-->176.10 for TEN, m/z 248.20-->130.20 for EMT and m/z 230.10-->112.10 for Lamivudine (LAM). The method involves solid phase extraction from plasma, simple isocratic chromatographic conditions and mass spectrometric detection using an API 5000 instrument that enables detection at nanogram levels. Lamivudine was used as the internal standard. The proposed method has been validated with a linear range of 10-600 ng/ml for TEN and 25-2,500 ng/ml for EMT. The intrarun and interrun precision values are within 12.0% for TEN and 15.6% for EMT at their respective LOQ levels. The overall recoveries for TEN and EMT were 84.3% and 68.5%, respectively. Total elution time was as low as 2 min.

Simultaneous determination of hydrochlorothiazide, quinapril and quinaprilat in human plasma by liquid chromatography-tandem mass spectrometry.

A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the simultaneous estimation of hydrochlorothiazide, quinapril and its metabolite quinaprilat in human plasma. After solid phase extraction (SPE), the analytes and IS were chromatographed on a hypurity C8 (100 mm x 2.1 mm i.d., 5 microm particle size) column using 2 microL injection volume with a run time of 2.8 min. An isocratic mobile phase consisting of 0.5% (v/v) formic acid:acetonitrile (25:75, v/v) was used to separate all these drugs. The precursor and product ions of these drugs were monitored on a triple quadrupole mass spectrometer, operating in the multiple reaction monitoring mode (MRM) without polarity switch. The proposed method was validated over the range of 5-500 ng/mL for hydrochlorothiazide method and 5-1500 ng/mL for quinapril and quinaprilat. Inter-batch and intra-batch precision (coefficient of variation - % CV) across five validation runs lower limit of quantitation (LLOQ), lower quality control (LQC), middle quality control (MQC), higher quality control (HQC) and upper limit of quantitation (ULOQ) was less than 15. The accuracy determined at these levels was within +/-13% in terms of relative percentage error.

Rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of clonidine in human plasma.

A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the estimation of clonidine in human plasma. Clonidine was extracted from human plasma by using solid-phase extraction technique. Nizatidine was used as the internal standard. A Hypurity C18 (50 mm x 4.6 mm i.d., 5 microm particle size) column provided chromatographic separation of analyte followed by detection with mass spectrometry. The method involves a rapid solid-phase extraction from plasma, simple isocratic chromatography conditions and mass spectrometric detection that enables detection up to picogram levels with a total run time of 3.0 min only. The method was validated over the range of 50-2500 pg/mL. The absolute recoveries for clonidine (71.86%) and IS (69.44%) achieved from spiked plasma samples were consistent and reproducible.