Determination of propylthiouracil in pharmaceutical formulation by high-performance liquid-chromatography with a post-column iodine-azide reaction as a detection system

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

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.

Thiouracil: Comprehensive profile

Thiouracil, 2-sulfanylidene-1H-pyrimidin-4-one, has been used as anti-thyroid, coronary vasodilator, and in congestive heart failure. It was found to cause agranulocytosis and it is suspected to be teratogenic and carcinogenic. Owing to its high frequency of adverse reactions, especially agranulocytosis, its use was abandoned in favor of other, less toxic drugs, such as propylthiouracil and methimazole. Thiouracil refers both to a specific molecule consisting of a sulfated uracil and a family of molecules based upon the structure. An important member of this family is propylthiouracil, which is a thiourea antithyroid drug that acts by blocking the production of thyroid hormones; it also inhibits the peripheral deiodination of thyroxine to tri-iodothyronine. This profile is prepared to discuss and explain physical and chemical properties, proprietary and nonproprietary names of thiouracil and propylthiouracil. It also includes uses and applications, methods of preparation, thermal and spectral behavior and methods of analysis. In addition, metabolism, excretion and pharmacology of propylthiouracil are also discussed.