Percutaneous Delivery of Thalidomide and Its N-Alkyl Analogs

Purpose . The purpose of this study was to determine the permeation parameters of thalidomide and three of its N -alkyl analogs and to establish a correlation between the physicochemical properties of these compounds and their percutaneous rates of absorption.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41491/1/11095_2004_Article_370433.pd

Physicochemical Characterization and Solubility Analysis of Thalidomide and Its N-Alkyl Analogs

Purpose . The present study was primarily aimed at exploring the feasibility of improving percutaneous delivery via chemical manipulation of the thalidomide molecule to form analogs with improved physicochemical properties. N -Alkyl analogs were synthesized with the belief that these would be suitably hydrophobic and far less crystalline than the reference compound. This article presents their physicochemical properties.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41489/1/11095_2004_Article_364706.pd

Targeted Precise Quantification of 12 Human Recombinant Uridine-Diphosphate Glucuronosyl Transferase 1A and 2B Isoforms Using Nano-Ultra-High-Performance Liquid Chromatography/Tandem Mass Spectrometry with Selected Reaction Monitoring

Quantification methods employing stable isotope-labeled peptide standards and liquid chromatography–tandem mass spectrometry are increasingly being used to measure enzyme amounts in biologic samples. Isoform concentrations, combined with catalytic information, can be used in absorption, distribution, metabolism, and excretion studies to improve accuracy of in vitro/in vivo predictions. We quantified isoforms of uridine-diphosphate glucuronosyltransferase (UGT) 1A and 2B in 12 commercially available recombinant UGTs (recUGTs) (n = 49 samples) using nano-ultra-high-performance liquid chromatography–tandem mass spectrometry with selected reaction monitoring). Samples were trypsin-digested and analyzed using our previously published method. Two MRMs were collected per peptide and averaged. Where available, at least two peptides were measured per UGT isoform. The assay could detect UGTs in all recombinant preparations: recUGTs 1A1, 1A3, 1A4, 1A6, 1A7, 1A8, 1A9, 1A10, 2B4, 2B7, 2B15, and 2B17, with limit of detection below 1.0 pmol/mg protein for all isoforms. The assay had excellent linearity in the range observed (2–15.5 pmol/mg, after dilution). Examples of concentrations determined were 1465, 537, 538, 944, 865, 698, 604, 791, 382, 1149, 307, and 740 pmol/mg protein for the respective isoforms. There was a 6.9-fold difference between the maximum and minimum recUGT concentrations. The range of concentrations determined indicates that catalytic rates per mg total protein in vitro will not accurately reflect isoform inherent specific activity for a particular drug candidate. This is the first report of a targeted precise quantification of commercially available recUGTs. The assay has potential for use in comparing UGT amounts with catalytic activity determined using probe substrates, thus allowing representation of catalysis as per pmol of UGT isoform

Targeted Quantitative Proteomics for the Analysis of 14 UGT1As and -2Bs in Human Liver Using NanoUPLC–MS/MS with Selected Reaction Monitoring

Targeted quantitative proteomics using heavy isotope dilution techniques is increasingly being utilized to quantify proteins, including UGT enzymes, in biological matrices. Here we present a multiplexed method using nanoLC–MS/MS and multiple reaction monitoring (MRM) to quantify 14 UGT1As and UGT2Bs in liver matrices. Where feasible, we employ two or more proteotypic peptides per protein, with only four proteins quantified with only one proteotypic peptide. We apply the method to analysis of a library of 60 human liver microsome (HLM) and matching S9 samples. Ten of the UGT isoforms could be detected in liver, and the expression of each was consistent with mRNA expression reported in the literature. UGT2B17 was unusual in that ∼30% of liver microsomes had no or little (<0.5 pmol/mg protein) content, consistent with a known common polymorphism. Liver S9 UGT concentrations were approximately 10–15% those of microsomes. The method was robust, precise, and reproducible and provides novel UGT expression data in human liver that will benefit rational approaches to evaluate metabolism in drug development

Special Section on Prediction of Human Pharmacokinetic Parameters from In Vitro Systems-Perspective A Perspective on the Prediction of Drug Pharmacokinetics and Disposition in Drug Research and Development

ABSTRACT Prediction of human pharmacokinetics of new drugs, as well as other disposition attributes, has become a routine practice in drug research and development. Prior to the 1990s, drug disposition science was used in a mostly descriptive manner in the drug development phase. With the advent of in vitro methods and availability of human-derived reagents for in vitro studies, drugdisposition scientists became engaged in the compound design phase of drug discovery to optimize and predict human disposition properties prior to nomination of candidate compounds into the drug development phase. This has reaped benefits in that the attrition rate of new drug candidates in drug development for reasons of unacceptable pharmacokinetics has greatly decreased. Attributes that are predicted include clearance, volume of distribution, halflife, absorption, and drug-drug interactions. In this article, we offer our experience-based perspectives on the tools and methods of predicting human drug disposition using in vitro and animal data