The U.S. Food and Drug Administration (FDA) approved the popular thyroid medication Synthroid yesterday after 50 years of being marketed without the administration's official endorsement. Synthroid has been sold for decades, but the FDA never required the drug to go through its formal approval process. However, in 1997 the administration discovered potency problems among medications in Synthroid's class of drugs that placed patients at risk of developing an overactive thyroid. At that time, the government ruled that all medications in the levothyroxine sodium class submit applications for official FDA approval.

Abbott Laboratories, Synthroid's maker, only recently applied for authorization after the FDA set a deadline that would have required the pharmaceutical giant to gradually reduce distribution of the drug. Current research on Synthroid indicates that the drug can increase the risk of coronary problems in patients with cardiovascular disorders such as angina, coronary artery disease and hypertension.