Robert Shi

High Performance Liquid Chromatographic Determination of Pentamidine in Plasma

Abstract A high performance liquid chromatographic method for quantitating pentamidine in plasma has been developed. Sample clean-up involved precipitating plasma with acetonitrile containing the internal standard, hexamidine. The supernatant was passed through a C8 Bond Elut column and eluted with a methanolic solution of sodium 1-heptanesulfonate. The eluate was then analyzed on an Altex C8 column with a mobile phase consisting of 45% CH8CN, 0.02% detramethylammonium chloride and 0.1% H3PO4. Using fluorescence detection (EX: 275 nm and EM: 340 nm), the detection limit was 1.25 ng/ml for 0.5 ml of plasma. The coefficients of variation for interday and intraday were around 10%.

High Performance Liquid Chromatographic Assay for Basic Amine Drugs in Plasma and Urine Using a Silica Gel Column and an Aqueous Mobile Phase. II. Chlorpheniramine

Abstract A high performance liquid chromatographic [HPLC] method that involves the use of a silica gel column and an aqueous mobile phase for quantitation of chlorpheniramine in plasma and urine is presented. Alkalinized samples are cleaned by extraction with pentane [containing 1% CH3CN], and the extraction is followed by evaporating the solvent and reconstituting the residue in a small amount of mobile phase. An aliquot of this solution is analyzed by an HPLC system with an Ultrasphere Si Column, an aqueous mobile phase at pH 7 containing 60% CH3CN and 7.5 mM [NH4]2HPO4, and UV detection at 200 nm. Although the average recovery of extraction is 58% ± SD 10%, the detection limit for the method is 0.7 ng/ml in plasma and 100 ng/ml in urine [s/n = 3] for 0.5 ml samples. The coefficients of variation [CV] on the results of samples run to measure interday and intraday precision and the bias on control samples were all 10% or less. We have used the method in a bioavailability study of a controlled release for...

High-performance liquid chromatographic assay of basic amine drugs in plasma and urine using a silica gel column and an aqueous mobile phase : I. Amiloride

A high performance liquid chromatographic [HPLC] method that involves the use of a silica gel column and an aqueous mobile phase for quantitation of chlorpheniramine in plasma and urine is presente...

Regulated drug bioanalysis for human pharmacokinetic studies and therapeutic drug management

Regulated drug bioanalysis (i.e., determination of drug concentrations in biological matrices for regulated studies) usually refers to animal toxicokinetics, bioavailability/bioequivalence and clinical pharmacokinetic studies. However, there is another important regulated drug bioanalysis - therapeutic drug management (TDM). In the USA, TDM is regulated by Clinical Laboratory Improvement Amendments. In this article, we review and compare human pharmacokinetic sample analysis and TDM sample analysis. The US FDA/Bioanalytical Method Validation Guidance and the American Association for Clinical Chemistry/TDM Roundtable Recommended Generic Assay Validation Guidance are also compared. Some regulated drug bioanalysis issues, such as terminology, validation concepts and acceptance criteria, are discussed. Fostering interaction between bioanalysts from pharmaceutical science and clinical chemistry and reducing the regulatory gaps between different agencies for drug bioanalysis is our objective.

High-performance liquid chromatographic assay for basic amine drugs in human plasma with a silica gel column and an aqueous mobile phase. IV, Albuterol

Abstract A high performance liquid chromatographic (HPLC) assay is presented for the determination of albuterol in human plasma. Sample analysis is performed with a silica gel column and an aqueous mobile phase. Plasma samples are extracted with chloroform containing di(2-ethylhexyl) phosphate. Samples are back extracted into a hydrochloric acid solution. A fluorescence detector is used for this assay. the detection limit of the assay is 0.2 ng/ml for 0.5 ml plasma samples. This method has been used in a bioavailability study of albuterol sulfate tablets (4.8 mg) given to healthy volunteers.

Ion-pair liquid chromatographic analysis of phenylpropanolamine in plasma and urine by post-column derivatization with O-phthalaldehyde

Abstract A high pressure Liquid chromatographic analysis of phenylpropano Lamine in plasma and urine by post-column derivatzaition with o-phthalaldehyde is described. Plasma samples are extracted with methylene chloride under alkaline conditions. Urine is diluted with mobile phase without extraction. Using fluorescence detection, the method is sufficiently sensitive (2 ng/ml in 0.5 ml of plasma and 0.5 mcg/ml in 0.2 ml of urine) so that phenylpropano lamine concentrations in plasma or urine may be measured for up to 24 hours following a 75 mg oral dose. Coefficients of variation for inter-day and intra-day precision are less than 10%.

High-Performance Liquid Chromatographic Assay for Meptazinol and Metabolite in Plasma and Urine Using a Silica Gel Column and an Aqueous Mobile Phase

Abstract An HPLC method for quantitating meptazinol, a synthetic narcotic analgesic, and its glucuronide in plasma and urine is presented. the method involves extraction from plasma with methylene chloride under alkaline conditions (pH = 9.7). Urine samples are injected without further preparation following addition of internal standard. the conjugate metabolite of meptazinol was hydrolyzed with β-glucuronidase. Samples are analyzed using an Ultrasphere Si column with an aqueous mobile phase of 65% acetonitrile and 5 mM dibasic ammonium phosphate at pH = 7.0. the flow rate is 1.0 ml/min. Fluorescent detector settings were 275 nm and 315 nm for excitation and emission wavelengths, respectively. Detection limits were 2 and 5 ng/ml in plasma and 50 and 70 ng/ml in urine for meptazinol and the hydrolyzed glucuronide, respectively. the coefficients of variation for interday and intraday precision were less than 10%. This method has been used in pharmacokinetic studies of i.v. and i.m. formulations involving 13...

Erratum to: A Simple and Sensitive LC–MS/MS Method for Simultaneous Determination of Temsirolimus and Its Major Metabolite in Human Whole Blood

A simple, fast and sensitive LC–MS/MS method was developed and validated for the simultaneous determination of the concentrations of temsirolimus and its major metabolite, sirolimus, in human whole blood. The blood sample (100 μL) after adding temsirolimus-d7 and sirolimus-d3 internal standards was precipitated with 0.200 mL of methanol/0.300 M zinc sulfate (70/30, v/v), then analyzed by a Shimatzu LC system coupled to a Sciex API-5000 mass spectrometer. The chromatographic separation was carried out on a BDS Hypersil C8 column (50 × 3.0 mm, 5 μm) at 50 °C with a mobile phase composed of methanol/water/formic acid (72/28/0.1) (v/v/v) containing 2.50 mM ammonium acetate. Mass spectrometric detection was performed using electrospray positive ionization with multiple reaction monitoring mode. This method was validated from 0.250 to 100 ng mL−1 for temsirolimus and 0.100 to 40.0 ng mL−1 for sirolimus. The lower limits of quantitation were 0.25 ng mL−1 for temsirolimus and 0.1 ng mL−1 for sirolimus. The intra-day and inter-day precisions (CV %) of spiked quality control (QC) samples were less than 10.4 and 9.6 %, respectively. The accuracies as determined by the relative error for QC samples were less than 12.1 % for intra-day and 7.3 % for inter-day. No significant matrix effect was observed. This method has been successfully applied to analyze clinical pharmacokinetic study samples. The assay reproducibility was also demonstrated by using incurred samples.