ABSTRACT
A high-performance liquid chromatographic method is described for the determination of paroxetine in human plasma. Dibucaine was used as the internal standard. Paroxetine was isolated by solid phase extraction using a Bond-Elut C18 extraction column. Separation was obtained using a reversed-phase column under isocratic conditions with fluorescence detection. The sample volume was 500 microliters of plasma. The intra- and inter-assay accuracy and precision, determined as relative error and relative standard deviation, respectively, were less than 10%. The lower limit of quantitation, based on standards with acceptable relative error and relative standard deviation, was 10 ng ml-1. No endogenous compounds were found to interfere. The linearity was assessed in the range 5-100 ng ml-1. Stability of paroxetine during processing (autosampler) and in plasma was checked. This method proved suitable for bioequivalence studies following multiple doses in healthy volunteers.
Subject(s)
Antidepressive Agents, Second-Generation/blood , Chromatography, High Pressure Liquid/methods , Paroxetine/blood , Selective Serotonin Reuptake Inhibitors/blood , Antidepressive Agents, Second-Generation/pharmacokinetics , Humans , Paroxetine/pharmacokinetics , Reference Standards , Reproducibility of Results , Sensitivity and Specificity , Selective Serotonin Reuptake Inhibitors/pharmacokinetics , Spectrometry, Fluorescence , Therapeutic EquivalencyABSTRACT
A rapid and simple HPLC method is described for the determination of Bobel-24 (2,4,6-triiodophenol) and other iodinated derivatives in biological samples. The sample preparation was liquid-liquid extraction before injection onto the HPLC system. 2,6-Diiodo-4-methylphenol was used as internal standard. Separation was obtained using a reversed-phase column under isocratic conditions. The mobile phase consisted of water-acetonitrile (62:38). 2,4,6-Triiodophenol was detected at 277 nm. This method was used for Bobel-24 determination in plasma, urine, synovial liquid and different tissues. The assay was applied to pharmacokinetic studies in dog and horse plasma and different dog tissues for tissue distribution profiles toxicological and metabolic studies. In addition, this method for biological samples can be applied to non-biological samples such as pharmaceutical formulations in stability studies and quality control assays.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/analysis , Chromatography, High Pressure Liquid/methods , Phenols/analysis , Animals , Anti-Inflammatory Agents, Non-Steroidal/metabolism , Anti-Inflammatory Agents, Non-Steroidal/pharmacokinetics , Dogs , Horses , Phenols/metabolism , Phenols/pharmacokinetics , Rats , Tissue DistributionABSTRACT
A simple robust high-performance liquid chromatographic method is described for the determination of ranitidine in microvolumes of human serum. The drug of interest was isolated using liquid-liquid extraction with dichloromethane and back-extraction with 0.1% phosphoric acid and separation was obtained using a reversed-phase column under isocratic conditions, with ultraviolet detection at 313 nm. Intra-day and inter-day coefficients of variation ranged from 1 to 6% and 3 to 10%, respectively. Accuracy of the assay was less than 10% at all concentrations. The limit of detection and the limit of quantitation were 2 and 7 ng/ml, respectively. The linearity was assessed in the range 10-1000 ng/ml. It was shown that a group of common drugs co-administered with ranitidine did not interfere with its determination. The applicability of this method for the pharmacokinetic study of ranitidine following i.v. infusion in patients was demonstrated using only 100 microl of serum. The ruggedness of the assay was demonstrated over a three-year period.
Subject(s)
Anti-Ulcer Agents/blood , Histamine H2 Antagonists/blood , Ranitidine/blood , Anti-Ulcer Agents/pharmacokinetics , Chromatography, High Pressure Liquid , Histamine H2 Antagonists/pharmacokinetics , Humans , Ranitidine/pharmacokinetics , Reproducibility of Results , Sensitivity and Specificity , Spectrophotometry, UltravioletABSTRACT
A rapid and simple HPLC method is described for the determination of imipenem in human plasma. After blood collection, plasma was separated by centrifugation and immediately stabilized with 3-morpholinopropanesulfonic acid (MOPS) and ethylene glycol solution (1:1). The sample preparation, before injection into HPLC, was ultrafiltration. The mobile phase was boric acid buffer. The imipenem was detected at 300 nm and cilastatin sodium, coadministered, did not interfere. Calibration curves in human plasma were linear from 0.1 to 100 microg/ml. The limit of detection was 0.030 microg/ml. Inter-day precision at 0.1 microg/ml, determined as the coefficient of variation, was 6.26%. Only 250 microl of plasma was required in our assay. Due to the limited stability of imipenem [G.B. Smith et al., J. Pharm. Sci., 79 (1990) 732], stability studies in plasma were done to establish appropriate storage conditions. The assay was applied to pharmacokinetic studies in patients.
Subject(s)
Imipenem/blood , Thienamycins/blood , Chromatography, High Pressure Liquid , Drug Stability , Humans , Imipenem/pharmacokinetics , Reproducibility of Results , Sensitivity and Specificity , Thienamycins/pharmacokinetics , UltrafiltrationABSTRACT
A high-performance liquid chromatographic method is described for the determination of free captopril in human plasma N-Acetyl-L-cysteine (NAC) was used as an internal standard. Plasma samples were immediately derivatized with N-(1-pyrenyl)maleimide (NPM) and stabilized with 11 M HCl. The drug of interest was isolated using a liquid-liquid extraction with ethyl acetate and separation was obtained using a reversed-phase column under isocratic conditions with fluorescence detection. The sample volume was 150 microliters plasma. The intra- and inter-day accuracy and precision, determined as relative error and coefficient of variation respectively, were less than 10%. The lower limit of quantitation, based on standards with acceptable coefficients of variation, was 25 ng/ml. No endogenous compounds were found to interfere. The linearity was assessed in the range of 25-600 ng/ml. This method has been demonstrated to be suitable for pharmacokinetic studies in humans.
