Current Approaches for Investigating and Predicting Cytochrome P450 3A4-Ligand Interactions

Abstract

Cytochrome P450 3A4 (CYP3A4) is the major and most important drug-metabolizing enzyme in humans that oxidizes and clears over a half of all administered pharmaceuticals. This is possible because CYP3A4 is promiscuous with respect to substrate binding and has the ability to catalyze diverse oxidative chemistries in addition to traditional hydroxylation reactions. Furthermore, CYP3A4 binds and oxidizes a number of substrates in a cooperative manner and can be both induced and inactivated by drugs. In vivo, CYP3A4 inhibition could lead to undesired drug-drug interactions and drug toxicity, a major reason for late-stage clinical failures and withdrawal of marketed pharmaceuticals. Owing to its central role in drug metabolism, many aspects of CYP3A4 catalysis have been extensively studied by various techniques. Here, we give an overview of experimental and theoretical methods currently used for investigation and prediction of CYP3A4-ligand interactions, a defining factor in drug metabolism, with an emphasis on the problems addressed and conclusions derived from the studies.

Effect of an anxiolytic botanical containing Souroubea sympetala and Platanus occidentalis on in-vitro diazepam human cytochrome P450-mediated metabolism

“…This may due to the allosteric behaviour or selectivity of CYP3A4. Although still under debate, it is well accepted that multiple substrates can simultaneously bind to CYP3A4 inside or near the active site, affecting catalytic activity . As a result, potency may vary when different substrates are used in the assay …”

“…Although still under debate, it is well accepted that multiple substrates can simultaneously bind to CYP3A4 inside or near the active site, affecting catalytic activity. [32] As a result, potency may vary when different substrates are used in the assay. [33] The findings in this in-vitro study suggest that the extracts of S. sympetala and P. occidentalis, alone or in combination, have the potential to affect the efficacy and safety of co-administered DA products, as well as other benzodiazepines, in certain conditions.…”

Identifying the reactive metabolites of tyrosine kinase inhibitors in a comprehensive approach: Implications for drug‐drug interactions and hepatotoxicity

“…The various types of MBI have been thoroughly reviewed, and are illustrated in Figure 24 using some typical structural alerts (acetylene derivatives, aliphatic or aromatic amines, and 1,3-benzodioxoles). 14,[79][80][81] In vitro, MBI is concentration-, NADPH-, and time-dependent, and different assay procedures make it possible to distinguish among the different above-mentioned inactivation mechanisms. In any case, MBI is irreversible in vivo, so that the loss of catalytic activity can only be restored by de novo synthesis of the enzyme.…”

“…82 F I G U R E 2 4 Potential pathways leading to cytochromes P450 inactivation The potential of TKI to cause DDI has been explored using in vitro expriments with different CYP probe substrates to identify which enzyme is inactivated. Attempts to clarify the type of CYP inactivation (quasiirreversible and irreversible) have been performed using different approaches 14,79 : UV/visible spectroscopy (absorbance in Soret region), dialysis experiments and LC-MS detection of adducts in RM trapping experiments.…”

An in vitro system for measuring genotoxicity mediated by human CYP3A4 in Saccharomyces cerevisiae

“…CYP3A4 constitutes 50% of the P450 activity in the human liver [Yang et al, 2010] and is expressed in other tissues exposed to food carcinogens, such as the small intestine [Ding and Kaminsky, 2003;Thummel, 2007;Gundert-Remy et al, 2014]. While CYP3A4 metabolizes many pharmaceuticals, its substrate binding site is wider [Sevrioukova and Poulos, 2015;Guengerich et al, 2016], rendering a lower affinity for particular compounds. Epidemiological studies are unclear whether CYP3A4 polymorphisms are linked to higher rates of xenobiotic-associated cancer [Klein and Zanger, 2013;Zanger and Schwab, 2013].…”