Bridging Pharmaceutical Analysis with Computational Chemistry to Ascertain the Pharmacokinetic and Toxicological Profiling of Febuxostat and its Diacid Impurity

Abstract

Drug degradation may change the pharmacological action and results in altered therapeutic and toxicological profile of drug. Identification of degradation product is good opportunity in the drug discovery, as non-toxic impurities can be considered for the new pharmacological potentials. Additionally, development of computer based in-silico model and methods further assist in prediction of pharmacokinetic, dynamic as well as biological activities which make drug discovery process more unfailing. In present work, Febuxotat (FEB) was subjected to forced degradation experiments and the formed degradation products were separated and resolved using optimized HPLC method. Further the study was extended to enrich its alkali degradation product and was ascertained using 1H NMR spectroscopy and mass spectrometry. The ADME/Toxicological properties of alkali degradation product were determined by using Admet SAR 2.0. The method was validated as per ICH guidelines Q2 (R1). In forced degradation experiments, substantial degradation of FEB was observed under acid, alkali, wet heat, dry heat and oxidative conditions, however, FEB was found stable to photolytic conditions. The drug and its formed degradation products separated and resolved from each other on Waters SunFire C8 (250 × 4.6 mm, 5 µm) column using blend of methanol: 20 mM potassium phosphate buffer (pH 3.0) (80: 20 % v/v). From the 1H NMR spectroscopy and mass spectrometry the enriched alkali degradation product was confirmed as 2-[3-carboxy-4-(2-methylpropoxy) phenyl]-4-methyl-1,3-thiazole-5-carboxylic acid (diacid FEB). Febuxostat and diacid Febuxostat was found non-toxic for carcinogenicity (binary), eye corrosion, eye irritation and Ames mutagenesis during ADME/Tox studies. However, both were found hepatotoxic. A simple, accurate, precise, and robust stability indicating HPLC method was developed and validated for the estimation of FEB in bulk and tablet dosage form. Based on ADME/Tox both were found to hepatotoxic. Henceforth, based on our evidences, one should use FEB with precaution in patient suffering from liver disease.