Stability-indicating assay, dissolution, and content uniformity of sodium levothyroxine in tablets

A reverse-phase high-performance liquid chromatographic (HPLC) method for determining sodium levothyroxine in tablet formulations is described. The sodium levothyroxine was extracted from tablets using a mobile phase consisting of 60% acetonitrile and 40% aqueous buffer. After centrifugation 200 microliter of the solution was chromatographed on a 10-micron C18 column. The method gave accurate results when tested against the USP method, by the standard additions method, and by the spiked-placebo method. The method can also be used to determine content uniformity and dissolution of sodium levothyroxine tablets.