RPR manufacture of Forest's Levothroid lacked adequate stability data -- FDA warning letter.

Executive Summary

RPR LEVOTHROID STABILITY TESTING PROCEDURES CITED IN WARNING LETTER sent to the company by FDA's San Juan, P.R. district office. Rhone-Poulenc Rorer has "failed to generate adequate stability data to support the 24-month expiration date assigned to...lots of Levothroid 88 mcg, 112 mcg and 137 mcg tablets manufactured and distributed [by Forest Labs] during 1993 and 1994," FDA said in its Nov. 4 warning letter. "The expiration date was not based on data from an adequate number of batches, it was based on accelerated data from a single batch of each strength," FDA charged.