Development and validation of novel LC MS MS methods for simultaneous estimation of drugs and their metabolites

Abstract

Modern drug development process relies heavily on drug level estimation in the physiological fluids i.e. bioanalysis. Bioanalysis has become an indispensable part of various studies like pharmacokinetic evaluation of drug, in vivo in vitro correlations (IVIVC) establishment procedures, bioequivalence studies, in therapeutic drug monitoring and various other biomedical arenas. Due to increasing cost of medications, more and more generic versions of innovator formulations are being introduced into the market. The aim of this study is to develop and validate a novel LC-MS/MS method for the drugs nitroglycerin and ursodiol and to test the BE of test formulations against their corresponding innovator versions. Based on the fact that these drugs undergo biotransformation to a great extent, assessment of net bioavailability must include quantification of drugs with their respective active metabolites. The method developed for the quantification of NTG and its metabolites is more sensitive as the LLOQ is of the order of pg/mL with shorter run-time when compared with the earlier reported methods, LLOQ and run-times. The method developed for ursodiol quantifies both free and bound metabolites simultaneously with very short run-time and less flow rate when compared with earlier reported methods in which more time was required to convert the metabolites into parent compound by enzyme hydrolysis. The developed methods were applied for testing bioequivalence of test formulations against their innovator versions in healthy human volunteers conducted under clinical set-up. Occurrences of adverse events were also recorded. With the aid of all the parameters obtained, formulations are tested for their BE and safety. Thus, each method developed and validated has its own advantages with good sensitivity and specificity and hence proves to be suitable for their determination in human plasma. newline newline newline