What is Cytochrome P450?

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Cytochromes P450 (CYP) is a superfamily of proteins involved in metabolism and inactivation of foreign substances and toxins. Each protein in this family is highly specialized with unique, dedicated pathways inside the cell. CYPs are transmembrane proteins commonly found in the plasma membrane of the endoplasmic reticulum in liver cells and interact with ligands on both sides1. Using heme as a cofactor, these proteins aid in the...  Read More

2018 Society of Toxicology Annual Meeting — Hot Topics

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The annual Society of Toxicology (SOT) meeting is the largest toxicological meeting in the world. The 57th Annual Meeting and ToxExpo was held in San Antonio, Texas, and drew more than 6,100 scientists from Europe, Africa, Asia, Canada, and almost every state of the United States. This is where scientists go to discover all the advances in toxicology from the past year and to meet with colleagues,...  Read More

Humanized Mice at the Summer Toxicology Forum

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The 43rd annual Summer Toxicology forum meeting was held on July 10-12, 2017 in Annapolis Maryland. The afternoon of July 10th was dedicated to a section titled "Use of Humanized Mice for Drug Development". The session was moderated by James Monroe, PhD, senior principle scientist at Merck Research Laboratories, and included presentations by researchers at the FDA, Merck, Yale, and Taconic Biosciences followed by a panel discussion...  Read More

Quality and Study Design Considerations for Carcinogenicity Testing with the rasH2

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75% of mouse carcinogenicity studies submitted to the FDA utilize the rasH2 mouse model (Tg.rasH2), a model accepted by the FDA as an alternative to the two-year in vivo bioassay for predicting human carcinogenic risk. In an evolving carcinogenicity testing landscape, with the utility of two-year rat bioassay under re-consideration and changes under consideration to the ICH guidelines for carcinogenic risk assessment, several key questions come to...  Read More

Improving Your ADME/Tox Processes

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Despite initiatives to improve the regulatory arena to speed up drug development and therefore reduce the cost of approval, it is still a long and expensive process to bring drugs to market. As a result, resources must be directed primarily to the drug candidates most likely to work. The key to improving that situation lies in refining early-stage drug screening through the use ADME/Tox. In the Nov...  Read More

When Is Less More In Carcinogenicity Testing?

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The rasH2 mouse model is used for carcinogenicity testing of genotoxic and non-genotoxic compounds. Over the last decade, it has become the leading alternative to the traditional 2-year rodent lifetime bioassay. In a recent opinion article, Paranjpe et al. (Paranjpe et al., 2014, Toxicologic Pathology, XX: 1-10), evaluated study design of carcinogenicity studies using the rasH2 model, particularly with respect to the dose groups of the compound...  Read More