Page 8 - Shimadzu Journal vol.3 Issue3

Drug Discovery

Metabolic Studies of Drug Candidates for Neurological
Disorders and Asthma Based on GABA A Receptor Subtype
Selective Ligands using Mass Spectrometry

1
1
Revathi Kodali , Margaret L. Guthrie , Michael M. Poe , Michael R. Stephen , Rajwana Jahan , Charles W. Emala , James M. Cook , Douglas
1
2
1
1
1
1
Stafford , and Leggy A. Arnold 1
1: Department of Chemistry and Biochemistry and Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
2: Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA.

Abstract Introduction
Development of pre-clinical experimental models to understand the in Drug metabolism is process of converting hydrophobic xenobiotic to
vivo metabolic performance of a drug is important in the field of drug highly water soluble species by biochemical modification, facilitating
discovery. GABA-ergic drugs are historically used for the treatment of the elimination of drugs from the body. Metabolic stability refers to
neurological disorders such as neuropathic pain, schizophrenia and susceptibility of drugs to bio-transformational enzymes such as
anxiety but recently have shown potential to treat asthma. In the cytochrome P450, which are abundant in the liver. Microsomes and
present study, an in vitro microsomal assay was designed to evaluate S9 fractions are subcellular fractions of liver tissue. Microsomes are
the metabolic stability of GABA A receptor subtype selective ligands vesicles derived from the endoplasmic reticulum containing CYP 450
using microsomes and S9 fractions of human and mouse liver extracts. enzymes responsible for phase I biotransformation reactions. The S9
A LC-MS/MS method was developed to quantify the amount of drug fraction is a mixture of microsomes and cytosol containing both phase
degrading over a period of time using verapamil as internal standard. I and Phase II metabolic enzymes.
Herein, we will report the development, analysis and standardization
of a liver microsome stability assay using the Shimadzu LCMS-8040
triple quadrupole instrument at the MIDD.

Preg
NADP +
O2
Heme
NADPH
H2O
FAD

FMN

P450
Cytosol
Cytosol
17OHP

Endoplasmic Reticulum

CYP 450 system

64