Levothyroxine is the generic name for the thyroid hormone replacement drugs Synthroid, Levoxyl, Levothroid
, and Unithroid, for example. The majority of patients taking thyroid hormone replacement are on a levothyroxine drug.
This change is being made to help ensure that levothyroxine retains its potency over its shelf life -- a problem that levothyroxine has had in the past, and continues to have. The current requirement is that each pill must contain "not less than 90.