We describe a molecular modelling method for calculating the binding affinity of ligands for DNA. Though theoretically applicable to any form of noncovalent interaction, we concentrate on the case of predicting the sequence selectivity of a minor-groove binding ligand. The method is ba ...

The mouse lymphoma assay (MLA) using the thymidine kinase (Tk1) gene is widely used to detect the potential genotoxicity of a wide variety of chemical agents. The assay is recommended as a part of the core battery of genetic toxicology tests. Although the assay was developed more than 30 yr ago, there have ...

The use of the human S9 fraction in mutagenicity testing systems may be valuable for evaluating the mutagenicity of chemicals in humans. When using a crude human liver S9 fraction, which is obtained following the centrifugation of the tissue homogenate for 20 min at 9000g, in the Ames test, we may somet ...

The human homologue of the ether-a-go-go-related-gene (HERG) has been implicated in the “iatrogenic” long QT syndrome, with several products withdrawn from the market because of their interaction with this K + channel. The resultant impact on the pharmaceutical industry has been profou ...

From a pharmaceutical research point of view, it seems reasonable in the early phase of discovery to eliminate those drug candidates that are subject to bioactivation to electrophilic intermediates. Although rarely detectable per se, the structures of these intermediates often can be ...

Acyl glucuronides are unstable at physiologic pH and thus can result in free aglycone by hydrolysis and lead to positional isomers by acyl migration. Acylmigrated glucuronide isomers were shown to bind covalently to proteins in vitro and in vivo, causing potential toxicity, but the toxico ...

The Caco-2 cell culture model is used to determine the absorption potentials of drug candidates and the transport and metabolism mechanisms of drugs and dietary chemicals. The Food and Drug Administration (FDA) recognized the model system as useful in classifying a compound’s absorption ...

The parallel artificial membrane permeability assay (PAMPA), as a passive-permeability screen, is an excellent alternative to cellular models for the earliest absorption, distribution, metabolism, and excretion (ADME) primary screening of research compounds. PAMPA’s popu ...

The single-pass perfused rat intestinal model is an in situ perfusion method that can be used to determine regional disposition of drugs. It is useful for selecting a development candidate from a series of active compounds and for studying mechanisms of absorption and excretion. It is also usef ...

Drug permeability through cell monolayer is known to correlate well with in situ intestinal permeability and/or oral bioavailability. Several mammalian cell lines such as Caco-2, MDCK, MDCKII, and LLC-PK have been used to predict in vivo intestinal absorption of drugs. However, there are no ...

Drug transporters have been isolated from many tissues, including the intestines, liver, kidney, blood-brain barrier, and placenta, in animals and humans. There is increasing evidence that they play a very important role in drug absorption and disposition. By gaining a better understan ...

P-Glycoprotein (P-gp) is a multidrug transporter responsible for resistance to anticancer chemotherapy and physiologically involved in absorption, distribution, and excretion of a large number of hydrophobic xenobiotics. P-gp exhibits both an adenosine triphosphatase ( ...

This chapter focuses on the three most widely used in vitro protein binding techniques in pharmaceutical research, which each reflect a diversity of speed, data quality, and complexity. Chromatographic separation using a human serum albumin-immobilized column to allow relative ra ...

Techniques such as calorimetry, spectroscopy, and hydrodynamic methods can be used to investigate the binding energetics of drugs bound to macromolecules. In this chapter, the authors describe the use of isothermal titration calorimetry (ITC) to measure the binding energetics of dr ...

A brief summary of the pioneering work of Brodie, Gillette, and coworkers on the discovery and development of the concept of chemically reactive intermediates serves as the backdrop for this chapter on approaches to studying how chemicals modify thiols and other cellular nucleophiles. As ...

Transporters that use ATP are called ATP-binding cassette (ABC) transporters. One family of ABC transporters that plays a major role in the ability of the liver to eliminate various drugs is the multidrug resistance proteins (MRPs). There are nine cloned genes in the MRP (ABCC) subfamily. Gener ...

Besides its important role in folate homeostasis, membrane transport is a critical determinant of the antitumor activities of antifolate therapeutics used in cancer chemotherapy, such as methotrexate (MTX) and an exciting new generation of antifolates typified by Tomudex and Pem ...

Although investigators have often focused on the role of glutathione (GSH) in drug metabolism and protection from reactive oxygen species and toxic electrophiles, membrane transport processes also play a critical role in the overall homeostasis of GSH in the body. Although the liver is the ...

Sulfation is a major reaction in phase II drug and xenobiotic metabolism. It is catalyzed by a family of enzymes, the sulfotransferases (SULTs), and involves the enzymatic transfer of a sulfonate group from a donor molecule (known as 3′-phosphoadenosine 5′-phosphosulfate ) to either an hydro ...

It is widely recognized that the kidneys contain several enzymes capable of catalyzing the metabolism of drugs and toxicants to yield chemically reactive metabolites that can cause nephrotoxicity. Reactive metabolites generated in the kidneys, and metabolites translocated to t ...