Acid dissociation constant (also known as acid ionization constant), Ka, is the thermodynamic equilibrium constant for the dissociation in the context of acid-base reactions. The pKa is the pH at which the molecule is 50% protonated (ionized). Ionization of a compound alters its physical behavior and macro properties such as solubility and lipophilicity. Therefore the ionization of drug candidates and the distribution of the neutral and ionized species under physiological pH are important in determining the ADME properties of NCEs.

Assay Methodology

Quintara Discovery uses a spetrophotometric method to determine the pKa for test compounds. The UV-vis wavelength scans for test compound are obtained in buffers of varying pH. pKa is then determined by analyzing spectral for pH-sensitive chromophores.