NADPH is a critical cofactor supporting numerous biochemical reactions. In ADME-Tox studies, NAD(P)H regeneration is strongly recommended when using drug metabolizing enzymes (ex. Cytochrome P450 (CYP), Flavin-containing MonoOxygenases (FMO)), Recombinant CYPs (incl. bactosomes) or cellular fractions (Microsomes, S9). Currently, the most simple and cost-effective way to regenerate the NAD(P)H in situ and enzymatically is to use the commercially-available RapidStart™ NADPH Regenerating System (Xenotech-Sekisui). [Read more…]
Rat liver tritosomes are hepatic lysosomes that have been loaded with Tyloxapol (Triton WR 1339), a non-ionic surfactant. Tyloxapol is taken up by hepatocytes through endocytosis and is trafficked to lysosomal compartments. Tyloxapol containing lysosomes exhibit decreased density and can be more efficiently isolated away from contaminating cellular organelles that have overlapping densities with native lysosomes (1-3). [Read more…]
In 2008, the FDA released guidance for drug metabolite safety testing (MIST), emphasizing the importance of metabolite toxicity testing in the drug development process. Indeed, drug toxicity, which accounts for roughly 40% of clinical drug failures, is a leading cause of the high drug attrition rates that have contributed to the skyrocketing drug development costs witnessed over the past few decades.
Traditionally, drug metabolites have been both difficult and hugely expensive to synthesize. Conventional methods of metabolite synthesis, such as those that employ the use of microsomes (while they have proven valuable as a predictive tool, their productive capabilities could be limited by NCE stability) or synthetic chemistry, can be extremely costly and time consuming. Consequently, drugmakers often choose to forego metabolite synthesis (and subsequent metabolite toxicity testing ) early on in the drug development process, opting instead to wait until lead compounds are further along in development before carrying out these essential functions. This decision, perceived to be a calculated risk, ultimately comes at huge price, as drug makers lose millions each year on investments in lead drug candidates that eventually turn out to be failures due to toxicity.
Biomimetic Chemistry, on the other hand, possesses the advantages of both chemistry and biology and is thus a much more efficient tool for metabolite synthesis. In fact, with biomimetic chemistry, large scale metabolite generation is enabled in one step, by mimicking and optimizing the same biotransformation reactions that occur in the liver. [Read more…]
Meet Jean-François Têtu, our “Cells & related Services and Reagents” sales manager at MDO2014. This meeting will take place in Stuttgart at the MDO, an international symposium series for the science of drug metabolism, drug metabolizing enzymes & related areas.
An interesting poster has recently been published by XenoTech: “Selection of Human Liver S9 and Cytosol Fractions for Evaluating Clearance by Aldehyde Oxidase (AO): The Impact of Low Versus High AO Activity Lots” by Phyllis Yerino, Clayton Otwell, Zell Woodworth and David B Buckley (XenoTech, LLC, Lenexa, KS, USA). [Read more…]