Found this snippet earlier today. Mulling it over, I really am not sure if it is the most interesting thing I have read in quite a while. Or an empty article with virtually no reason to exist.
What is unusual is the very specific implication that the effect is from synthetic levothyroxine.
If there are any experienced biochemists around who would like to comment, I'd certainly like to read those comments.
• Latin American Journal of Pharmacy
• vol. 31, no. 05
Levothyroxine Exhibits Inhibitory Effect towards UDP-Glucuronosyltransferase (UGT) 1A6-Mediated 4-Methylumbelliferone (4-MU) Glucuronidation
Authors: Wang, Chuan-Qiang | Song, Ming-Zhu | Zhu, Hou-Wei | YI, Jia-Jun | Luan, Ming-Chun | Shi, Ai-Yuan | Qu, Yan-Qing
Document type: Comunicacion
Levothyroxine, a synthetic form of thyroid hormone, has been clinically used to treat thyroid hormone deficiency. UDP-glucuronosyltransferases (UGTs) are important phase II drug-metabolizing enzymes, and UGTs-inhibition based drug-drug interaction has been widely reported. The aim of the present study is to investigate the inhibitory effect of levothyroxine towards UGT1A6-catalyzed 4-methylumbelliferone (4-MU) glucuronidation. The results showed that levothyroxine inhibited UGT1A6-catalyzed 4-MU glucuronidation reaction in a dose-dependent manner. Furthermore, Lineweaver-Burk and Dixon plots showed the inhibition of UGT1A6 by levothyroxine was best fit to competitive inhibition, and the inhibition kinetic parameter (Ki ) was determined to be 15.3 μM. Given that UGT1A6 is one of the most important UGT isoforms catalyzing the glucuronidation reaction of many important clinical drugs, including aspirin and serotonin, inhibition of UGT1A6 activity by levothyroxine will significantly influence the pharmacokinetic behaviour of these drugs. Therefore, clinical drug-drug interaction due to the inhibition of UGT1A6 by levothyroxine should paid much attention.
Issue date: 2012
Document language: English
Journal: Latin American Journal of Pharmacy; vol. 31, no. 5
Origin: Colegio de Farmacéuticos de la Provincia de Buenos Aires
Extent: p. 743-745
Keywords: Drug-drug interaction; Levothyroxine; UDP-glucuronosyltransferases (UGTs)