Some of the pharmaceutical properties of thyroxine have important implications for the quality use of medicines. The stability of thyroxine tablets is limited and they may reach the expiry date before the bottle is finished. Administration should preferably be on an empty stomach and be consistent with respect to food and other drugs. The long half-life of thyroxine enables longer dosing intervals of up to a week if required. The two Australian brands of thyroxine are identical and patients can swap brands safely, but this should not be assumed for overseas brands.