Simultaneous Quantification of Propylthiouracil and Its N-β-d Glucuronide by HPLC-MS/MS: Application to a Metabolic Study

Abstract

Propylthiouracil (PTU) is commonly prescribed for the management of hyperthyroidism and thyrotoxicosis. Although the exact mechanism of action is not fully understood, PTU is associated with hepatoxicity in pediatric population. Glucuronidation mediated by uridine 5′-diphospho-glucuronosyltransferases (UGTs), which possess age-dependent expression, has been proposed as an important metabolic pathway of PTU. To further examine the metabolism of PTU, a reliable HPLC-MS/MS method for the simultaneous quantification of PTU and its N-β-D glucuronide (PTU-GLU) was developed and validated. The chromatographic separation was achieved on a ZORBAX Extend-C18 column (2.1 × 50 mm, 1.8 μm) through gradient delivery of a mixture of formic acid, methanol and acetonitrile. The electrospray ionization (ESI) was operated in its negative ion mode while PTU and PTU-GLU were detected by multiple reaction monitoring (MRM). This analytical method displayed excellent linearity, sensitivity, accuracy, precision, recovery and stability while its matrix effect and carry-over were insignificant. Subsequently, the in vitro metabolism of PTU was assessed and UGT1A9 was identified as an important UGT isoform responsible for the glucuronidation of PTU. The information obtained from this study will facilitate future mechanistic investigation on the hepatoxicity of PTU and may optimize its clinical application.

Lead Optimization of Butyrolactone I as an Orally Bioavailable Antiallergic Agent Targeting FcγRIIB

“…The poor metabolic stability of BTL-I is a significant limitation in terms of its pharmacokinetic properties. It was observed that the methyl ester group of BTL-I is crucial for its rapid metabolism, which was confirmed through in vitro metabolic profiles and similar metabolic half-lives in human liver microsomes (HLM) with different enzymatic cofactors (Figure A). − The t 1/2 of BTL-I in HLM with nicotinamide adenine dinucleotide phosphate (NADPH) and uridine diphosphate glucuronic acid (UDPGA) were 19.58 and 17.54 min, respectively, similar to that in HLM without cofactors ( t 1/2 = 16.99 min). These findings suggest that the methyl ester moiety of BTL-1 serves as the primary metabolic site for carboxylesterases, with BTL-1 primarily cleared through esterase metabolism, while metabolism by cytopigments (CYPs) and UGTs is minimal.…”

Predictive performance and verification of physiologically based pharmacokinetic model of propylthiouracil

“…Related studies have reported that glucuronidation mediated by uridine 50-diphospho-glucuronosyltransferases (UGTs) has been proposed as a potential metabolic pathway of PTU. In vitro experiments showed that the UGT1A9 inhibitor (magnolol) significant inhibition of PTU metabolism when the concentrations of various subtypes of UGTs enzyme inhibitors were 10 μM and 50 μM ( Li et al, 2021 ). Therefore, we tried to simulate the disposition process using UGT1A9 as the main metabolic enzyme.…”