Stability of an extemporaneously formulated levothyroxine sodium syrup compounded from commercial tablets.

The stability of 40 micrograms/mL extemporaneously formulated syrup from commercially available levothyroxine sodium tablets, using sorbitol 70% as the diluting vehicle, was studied. The concentration of levothyroxine sodium in the formulation was 40 micrograms/mL. The protocol included accelerated stability testing at temperatures of 40 deg, 50 deg, 60 deg, and 70 deg C and a high-performance liquid chromatography assay procedure using testosterone propionate as the internal standard. The data were analyzed using an Arrhenius plot to determine the shelf-life of formulation. The shelf-life was found to be approximately 15 days at 25 deg C and 47 days at 5 deg C.