Biotransformation of a Novel Antimitotic Agent, I-387, by Mouse, Rat, Dog, Monkey, and Human Liver Microsomes and In Vivo Pharmacokinetics in Mice

Abstract

ABSTRACT:3-(1H-Indol-2-yl)phenyl)(3,4,5-trimethoxyphenyl)methanone (I-387) is a novel indole compound with antitubulin action and potent antitumor activity in various preclinical models. I-387 avoids drug resistance mediated by P-glycoprotein and showed less neurotoxicity than vinca alkaloids during in vivo studies. We examined the pharmacokinetics and metabolism of I-387 in mice as a component of our preclinical development of this compound and continued interest in structure-activity relationships for antitubulin agents. After a 1 mg/kg intravenous dose, noncompartmental pharmacokinetic analysis in plasma showed that clearance (CL), volume of distribution at steady state (Vd ss ), and terminal half-life (t 1/2 ) of I-387 were 27 ml per min/kg, 5.3 l/kg, and 7 h, respectively. In the in vitro metabolic stability study, half-lives of I-387 were between 10 and 54 min by mouse, rat, dog, monkey, and human liver microsomes in the presence of NADPH, demonstrating interspecies variability. I-387 was most stable in rat liver microsomes and degraded quickly in monkey liver microsomes. Liquid chromatography-tandem mass spectrometry was used to identify phase I metabolites. Hydroxylation, reduction of a ketone group, and O-demethylation were the major metabolites formed by the liver microsomes of the five species. The carbonyl group of I-387 was reduced and identified as the most labile site in human liver microsomes. The results of these drug metabolism and pharmacokinetic studies provide the foundation for future structural modification of this pharmacophore to improve stability of drugs with potent anticancer effects in cancer patients.

Metabolic stability and its role in the discovery of new chemical entities

“…-During in vitro metabolic stability testing, systems based on different preclinical species are employed (i.e., human, mouse, rat, dog and monkey). As different model organisms are used in the experiments, interspecies variations in metabolic stability are typically observed (9,30,38,(94)(95)(96)(97)(98).…”

“…In another study Ahn et al (95) conducted in vitro biotransformation of a novel antimitotic agent, I-387, in HLM, MLM, RLM, DLM and MnLM. They demonstrated that the test compound was most stable in RLM with the longest t 1/2 and degraded rapidly in MnLM with the shortest t 1/2 .…”

Comparative Metabolism Study of Five Protoberberine Alkaloids in Liver Microsomes from Rat, Rhesus Monkey, and Human

“…However, the metabolic profile of PBAs in vitro has not aroused enough attention. As we all know, there were significant interspecies differences in the metabolism of some compounds [13,14]. The interspecies differences of PBAs have been rarely published.…”

In Vitro Biotransformation, Safety, and Chemopreventive Action of Novel 8-Methoxy-Purine-2,6-Dione Derivatives

“…A second alternative to in vivo metabolism assays of chemical compounds are in vitro screening assays with liver microsomes: they can predict the metabolic routes of tested compounds, as well as kinetics of these transformations [ 10 ]. Cytochrome P450 enzymes are involved in phase I reactions, whereas phase II reactions are commonly carried out by different transferase enzymes such as glutathione transferase and N -acetyltransferase [ 11 ]. As microsomal assays have a good reproducibility and performing them is straightforward, they are becoming a standard in vitro screening in drug discovery processes [ 12 – 14 ].…”

“…As microsomal assays have a good reproducibility and performing them is straightforward, they are becoming a standard in vitro screening in drug discovery processes [ 12 – 14 ]. Finally, liver microsomes from different species (such as rat, mouse, dog, monkey, and human) can be used to provide more accurate data [ 11 ].…”