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Abstract

The kinetics of the deiodination of levothyroxine in aqueous solution were studied over the pH range 1 to 12. Temperature dependence of the reaction was also studied. The log k - pH profile indicated that the kinetics of deiodination include proton attack on the anion and dianion in acidic solution and water attack on the anion and dianion in alkaline solution. A possible mechanism of the deiodination was discussed. The solid-state stability of levothyroxine sodium was studied at elevated temperatures; and the compound was found to undergo deamination on heating. The decomposition follows biphasic first-order kinetics, with the most rapid decomposition occurring at the beginning of heating.

Oral liquid levothyroxine treatment at breakfast: a mistake?

“…coffee temperature) do not alter the molecular properties or stability of L-T 4 . Studies on stability, carried out with tablet formulations, have shown that sodium L-T 4 gets rapidly degraded at 60 8C (15,16). Indeed, an Italian coffee 'espresso' is served at 80-90 8C (17).…”

Analysis of thyroid hormones in raw and treated waste water

“…At the pH of the aqueous part of the eluent (∼2.5) T 4 is quite hydrophobic [18], which enables good retention to the stationary phase upon introduction into the analytical column. In addition, the presence of an acidic buffer facilitated the formation of positive ions during ESI.…”

Design of Radioiodinated Pharmaceuticals: Structural Features Affecting Metabolic Stability towards in Vivo Deiodination

“…In fact, organic iodides can often undergo physical/chemical decomposition. Thyroxine, for instance, is already known to deiodinate in vitro in aqueous solution, upon UV irradiation, or in a pH‐ and temperature‐dependent manner . Thus, when assessing the metabolic stability of an iodinated pharmaceutical, it is crucial not only to analyze the carbon–iodine BDE, but also to understand how the whole molecule might interact with any metabolic pathway in vivo.…”