Abstract
The influence of excipients on the stability of sodium levothyroxine pentahydrate (LTSS) under ambient conditions and thermal stress was evaluated. Since LTSS is a synthetic hormone with a narrow therapeutic index, the interactions of LTSS with excipients can lead to a drastic diminution of therapeutic activity. Ten commonly used pharmaceutical excipients with different roles in solid formulations were chosen as components for binary mixtures containing LTSS, namely, starch, anhydrous lactose, D-mannitol, D-sorbitol, gelatin, calcium lactate pentahydrate, magnesium stearate, methyl 2-hydroxyethyl cellulose (Tylose), colloidal SiO2 (Aerosil) and talc. As investigational tools, universal attenuated total reflectance- Fourier transform infrared spectroscopy UATR-FTIR spectroscopy and thermal analysis were chosen and used as follows: UATR-FTIR spectra were drawn up for samples kept under ambient conditions, while thermoanalytical tools (TG/DTG/HF data) were chosen to evaluate the inducing of interactions during thermal stress. The corroboration of instrumental results led to the conclusion that LTSS is incompatible with lactose, mannitol and sorbitol, and these excipients should not be considered in the development of new generic solid formulations.
Highlights
Levothyroxine sodium pentahydrate (LTSS) is the sodium salt of the levo-isomer of thyroxine, an active physiological substance found in the thyroid gland [1,2]
As current practice in preformulation studies of solid or semisolid dosage forms, the analysis of binary mixtures consisting of equal masses of active pharmaceutical ingredients (APIs) and pharmaceutical excipients were reported for antiviral drug penciclovir [33], ketoconazole [34], atorvastatin calcium [35], rivaroxaban [36], roflumilast [37] or diazepam [38]
The binary mixtures were subjected to UATR-FTIR analysis in order to evaluate the interactions that may occur under ambient conditions, and later to thermal stress, in order to get an in-depth view for the thermal-induced interactions
Summary
Levothyroxine sodium pentahydrate (LTSS) is the sodium salt of the levo-isomer of thyroxine, an active physiological substance found in the thyroid gland [1,2]. Pharmaceutics 2020, 12, x FOR PEER REVIEW an active physiological substance found in the thyroid gland [1,2]. Endogenous production of triiodothyronine) is the primary 3,5,3′ triiodothyronine) is the function function of the human These[3]. Hormones are crucialare in crucial the regulation of many metabolic primary of thethyroid human[3]. Hormones are crucialare in crucial the regulation of many metabolic primary of thethyroid human[3]. thyroid
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