FDA narrows levothyroxine potency specs

Executive Summary

Levothyroxine sodium potency specifications are tightening in response to concerns that the drug's potency may deteriorate prior to its expiration date. Currently allowed up to 10 percent potency degradation over the course of the product's shelf life, the thyroid treatment will now be required to meet a 95 percent to 105 percent potency specification until the expiration date, consistent with the recommendations of a joint FDA advisory committee. Presented with FDA's analysis of stability data supplied by manufacturers, the Endocrinologic & Metabolic Drugs and Pharmaceutical Science Advisory Committees overwhelmingly recommended that potency specifications should be narrowed (1"The Pink Sheet" Oct. 9, 2006, p. 16). Manufacturers will have two years to comply with the specifications, according to FDA...