Simultaneous Determination of LogD, LogP, and pKa of Drugs by Using a Reverse Phase HPLC Coupled with a 96-Well Plate Auto Injector

Abstract

For years, the physicochemical properties of drug candidates have been used to predict their in vivo pharmacokinetic behaviors. Several theories and empirical correlations have been established by various researchers with the overall goal of expediting the drug candidate selection process, with greater confidence and faster turnaround. This study describes a 96-well reverse phase HPLC method, simultaneously determining LogD, LogP, and pK(a) values of drugs in a throughput mode. The LogD and LogP values of each compound were determined, based on the octanol-aqueous partitioning behavior of the charged and non-charged species under different pH values. The pK(a) value was determined by using the Polynomial fit between LogP and LogD and the equation LogD (pK(a)) approximately LogP-0.301. The advantages of this method are: low sample consumption, suitability for low solubility compounds, less restriction on compound purity, potential for higher throughput, precise data, and multiple determinations in one assay.

A Novel Method for the Investigation of Liquid/Liquid Distribution Coefficients and Interface Permeabilities Applied to the Water-Octanol-Drug System

“…As expected, and considering the concentrations of the respective drug detected after reaching the equilibrium in both phases, ibuprofen and paracetamol were the substances of highest lipophilicity (logD ow (7.4) of 1 and 0.75, respectively) followed by ketoprofen (0.19) and nadolol (−0.6). All logD ow (7.4) values are in close accordance with literature (9). For each drug the distribution coefficient was approximately the same if it was estimated just from the aqueous phase by comparing concentrations in the buffer initially and after 72 h (logD e (7.4)).…”

“…Most approaches are based on the shake-flask method, which is regarded as "the golden standard" (7). There is no common understanding for the time needed to reach equilibrium, not even for the same surface area and volume relation; the literature for experiments on 96-well plates reports any time between 10 min and 18 h (8,9). 2.…”

Drug development and bioanalytical method validation for a novel anticancer molecule, 4‐(dimethylamino)‐2‐(p‐tolylamino) thiazole‐5‐carbonitrile

“…The ionic state of any molecule depends on its pKa, which affects the pharmacodynamics and pharmacokinetic properties (Lee, Yu, & Crippen, 2008). Partition coefficient (LogP) is a good arbiter to predict bioavailability, which significantly contributes toward the toxicological and pharmacokinetic behavior of a molecule (Chiang & Hu, 2009;Di & Kerns, 2003;Laube, Klein, & Sadowski, 2015;Mandi, 2012). Experimental determination of distribution coefficient (LogD) can be considered as an essential part of the drug development process.…”

Mass Spectrometry and Drug Discovery

“…The shake-flask method is the most accurate method for log P or log D estimation; however, it is the most costly and time consuming. Faster and less expensive alternatives to the shake-flask method include computer-based in silico prediction, LC-MS retention time-based estimation, and a recent 96-well plate format coupled to LC-MS [77]. In the microtiter plate method, a deep 96-well plate is loaded with aqueous and organic phases at the appropriate pH along with the compound of interest, and then vortex mixed.…”