Microsomal Binding Assay
Creative Animodel provides microsomal binding assay to aid accurate assessment of hepatic intrinsic clearance and drug-drug interactions, which could provide efficiency and decrease knowledge cycle times in drug discovery.
Why Microsomal Binding Assay?
Design efforts in the early drug discovery phase frequently rely on intrinsic clearance (CLint) and cytochrome P450 (CYP) inhibitory potency (IC50) estimates derived during human liver microsomal incubations. Accounting for a few assumptions, these estimates can be expected to have proportional implications for oral dose requirements and therapeutic windows against pharmacokinetic drug-drug interactions. It has been well documented in the scientific literature that nonspecific binding of compounds to microsomal phospholipids will confound the experimental estimation of enzyme kinetic parameters with initial publications appearing > 40 years ago. More recent reports continue to point out that experimental estimation of CLint and IC50 needs to consider the fraction of unbound drug (fumic) into the metabolizing enzymes with relevant incubation in human liver microsomes (Equations 1 and 2). Without such consideration, inaccuracy arises from the assumption that all of the drug added to an in vitro incubation mixture is available for metabolism or inhibition. Many drugs bind nonspecifically to the membrane of the in vitro enzyme source. Therefore, it is important to note that extensive nonspecific microsomal binding is common for the chemical libraries of the pharmaceutical industry, particularly among lipophilic chemical entities.
Our Microsomal Binding Assay
Creative Animodel provides a series of experimental methods for the determination of fumic in order to ensure effective drug design in discovery.
• Determination of fumic by equilibrium dialysis
Our equilibrium dialysis can provide high throughput fumic data by using 96-well dialysis plates. In this method, wells are split into a donor side and a receiver side with a dialysis membrane. A mixture of microsomes and compound is added to the donor side while an equivalent buffer is added to the receiver side. After incubation at 37℃ for about 4-5 h, drug levels in the donor and receiver sides are determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and fumic values are calculated according to Equation 3, where Cb and Cm denote the amount of the compound in dialysis apparatus from buffer and microsomal solutions, respectively.
• Predictive in silico models for fumic
With years of experience, our experts have also developed in silico models using ligand-based approaches for predicting fumic from physicochemical properties-based models, pharmacophore-based classification models and more complex statistical models. The in silico models of fumic are complementary to experimental measurements. Our in silico models are valuable tools to aid chemical library design and prioritize multiple chemical series, which could provide efficiency and decrease knowledge cycle times in drug discovery.
• High-throughput compound profiling
• Competitive price and fast turnaround time
• Behavior difference monitoring between species
• Meeting the customers’ special requirements
Creative Animodel uses our extensive expertise and integrated techniques to provide microsomal binding assays. If you have any additional requirements or questions, please do not hesitate to contact us.
1. Gao H,; et al. Assessment of in silico models for fraction of unbound drug in human liver microsomes. Expert Opinion on Drug Metabolism & Toxicology. 2010, 6(5):533.