Panelist Arthur Kibbe, Ph.D., of the Nesbit School of Pharmacy, Wilkes University, Wilkes-Barre, Pa., said that if the potency levels of all these products on the market were tightened, the possibility of differences between products would also be lessened and would reduce the chance of adverse effects of switching from one product to another.
Dr. Jurgen Venitz, of the Virginia Commonwealth University School of Pharmacy, Richmond, said that as much as he supported the panel's recommendations, he felt that bioequivalence between products was really the bigger issue. One panelist referred to bioequivalence as “the 800-pound gorilla in the room.”
Speaking for AACE during the open public hearing, Dr. Jeffrey Garber, treasurer and chief of endocrinology at Harvard Vanguard Medical Associates, Boston, said that it has become “increasingly unlikely” that a patient will be given a therapeutically equivalent preparation, and that while the meeting was “a step in the right direction,” it did not address the broader issue of bioequivalence.
Speaking for the Endocrine Society, Dr. Leonard Wartofsky, president of the society, said that current FDA bioequivalence standards are not sensitive enough to detect small but meaningful differences between products, and that the FDA erred in allowing manufacturers to drop the warning that when a product is switched, patients need to call their physician and have their thyroid-stimulating hormone levels measured to retitrate their dose. He referred to a May 2005 meeting cosponsored by the FDA, American Thyroid Association, Endocrine Society, and AACE to review concerns about substitution and bioequivalence, and concerns that one product may be substituted for another—often unbeknownst to the physician—despite differences in potency.