The Food & Drug Administration (FDA) is requiring Abbott Laboratories to slow production of its popular thyroid medication Synthroid. Synthroid has been on the market for nearly 50 years but the FDA never required the drug to go through its formal approval process. Recently, the FDA discovered potency problems with Synthroid and other medications in the levothyroxine sodium class of drugs. However, two other drugs similar to Synthroid (Unithroid and Levoxyl) have applied for and received approval.

Patients currently taking Synthroid may have to change to another medication as the approval process is expected to take at least ten months. However, healthcare professionals stress the importance of consulting with a doctor before altering any medical treatment.

In addition to Synthroid, there are five other unapproved medications in the levothyroxine sodium family. However, Synthroid is the most popular with sales of nearly $425 million in 2000.