title: Thermal stability of synthetic thyroid hormone l-thyroxine and l-thyroxine sodium salt hydrate both pure and in pharmaceutical formulations.
abstract: In this paper, the thermal stability of pure l-thyroxine (THY) and l-thyroxine sodium salt hydrate (THYSS) vs. two pharmaceutical solid formulations commercialized on both Romanian and European market (with a content of 100μg, respectively 200μg THYSS per tablet) were investigated. In order to determine whether the presence of excipients affects the thermal stability of the active pharmaceutical ingredient (API), the preliminary study of thermal stability in air atmosphere was completed with an in-depth solid-state kinetic study. By kinetic analysis, the non-isothermal degradation of the selected active pharmaceutical ingredients vs. the solid formulation with strength of 200μg THYSS per tablet was investigated. Isoconversional methods (Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa and Friedman) were employed for the estimation of activation energies values, at five different heating rates, β=5, 7, 10, 12 and 15°Cmin(-1). Also, a fourth method was applied in the processing of data, namely NPK, allowing an objective separation in the physical and chemical processes that contribute to the thermal degradation of the selected compounds. A discussion of thermal stability from the kinetic point of view is also presented.
authors.affiliation: University of Medicine and Pharmacy "Victor Babeş", Faculty of Pharmacy, Eftimie Murgu Square 2, Timişoara, RO-300041, Romania.
authors.forename: Ionuţ
authors.initials: I
authors.lastname: Ledeţi
authors.affiliation: University of Medicine and Pharmacy "Victor Babeş", Faculty of Pharmacy, Eftimie Murgu Square 2, Timişoara, RO-300041, Romania. Electronic address: afulias@umft.ro.
authors.forename: Adriana
authors.initials: A
authors.lastname: Ledeţi
authors.affiliation: West University of Timisoara, Faculty of Chemistry-Biology-Geography, Research Center for Thermal Analysis in Environmental Problems, Pestalozzi Street 16, 300115, Timisoara, Romania.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Vlase
authors.affiliation: West University of Timisoara, Faculty of Chemistry-Biology-Geography, Research Center for Thermal Analysis in Environmental Problems, Pestalozzi Street 16, 300115, Timisoara, Romania.
authors.forename: Titus
authors.initials: T
authors.lastname: Vlase
authors.affiliation: University of Medicine and Pharmacy "Victor Babeş", Faculty of Medicine, Eftimie Murgu Square 2, Timişoara, RO-300041, Romania.
authors.forename: Petru
authors.initials: P
authors.lastname: Matusz
authors.affiliation: Politehnica University Timişoara, Faculty of Industrial Chemistry and Environmental Engineering, 6 Carol Telbisz, Timişoara, RO-300001, Romania.
authors.forename: Vasile
authors.initials: V
authors.lastname: Bercean
authors.affiliation: University of Medicine and Pharmacy "Victor Babeş", Faculty of Pharmacy, Eftimie Murgu Square 2, Timişoara, RO-300041, Romania.
authors.forename: Lenuţa-Maria
authors.initials: LM
authors.lastname: Şuta
authors.affiliation: Institute of Oncology "Prof.Dr.Ion Chiricuţă" 34-36 Republicii Street, Cluj-Napoca, RO-400015, Romania.
authors.forename: Doina
authors.initials: D
authors.lastname: Piciu
mesh_terms: D002152:Calorimetry, Differential Scanning; D004355:Drug Stability; D007700:Kinetics; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry; D013974:Thyroxine / Q000737:chemistry*
chemical_list: D004364:Pharmaceutical Preparations; D013974:Thyroxine
keywords: Isoconversional methods; Kinetic study; NPK method; Pharmaceutical formulation; Thyroxine; Thyroxine sodium salt