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Desiccated thyroid extract, or DTE, is a natural thyroid hormone therapy made from dried animal thyroid glands. About 1.5 million Americans rely on it to treat hypothyroidism, often after synthetic options failed to meet their needs.
FDA now classifies DTE as a biologic because it contains thyroglobulin, a protein that is not the product’s active ingredient. That reverses the agency’s own longstanding policy that inactive ingredients don’t determine whether a product is a biologic. Under FDA’s position, DTE is not eligible for compounding, and manufactured products remain available only through enforcement discretion. The agency promised guidance on its compliance priorities before August 2026 but has not issued it, leaving pharmacies, prescribers and patients unsure what comes next.
Where APC stands
APC’s position is clear: continuity of care comes first. In a citizen petition and letters to FDA, APC has asked the agency to reverse the classification, regulate DTE as a drug and protect access for patients who are stable on it today.
More than a century
DTE has been used to treat hypothyroidism for more than 100 years, and for decades FDA treated it as a drug.
August 2025
After first taking that position in a 2022 letter, FDA formally notified industry that animal-derived thyroid is a biologic. Nothing about the patients or the therapy had changed.
The consequence
The biologics pathway is more expensive and restrictive than the drug pathway. Biologics also can’t be compounded for patients who need custom strengths or dosage forms, or during drug shortages.
Who benefits
With compounding off the table and few companies able to afford the biologics pathway, a small number of manufacturers pursuing biologics licenses could control the market, limiting competition and likely driving up prices.
The science
FDA’s classification rests on thyroglobulin, a protein naturally present in thyroid tissue. But the pharmacological effect comes from T3 and T4, small-molecule thyroid hormones. FDA’s own guidance says a protein present only as an inactive ingredient does not make a product a biologic, and the agency made this change without rulemaking or a public comment period.
Reverse the biologic classification and ensure any approval proceeds through the drug pathway.
Clarify that FDA’s August 2025 notice is not an across-the-board ban on compounding DTE for individual patients with valid prescriptions.
Maintain enforcement discretion until an approved product or a clear, patient-protective transition pathway is in place.
Target demonstrable safety, quality or misbranding concerns rather than imposing a categorical prohibition.
APC filed a citizen petition with FDA in February 2026 on behalf of both 503A pharmacies and 503B outsourcing facilities, asking the agency to reverse the biologic classification, confirm that any approval should proceed through the drug pathway and take a risk-based approach to DTE compounding. In August 2026, a group of compounding pharmacists filed an additional petition, arguing that thyroglobulin is a carrier, not the active ingredient. That petition asks FDA to revoke the biologic classification, classify DTE as a drug and withdraw the 2022 and 2025 letters that describe DTE as a biologic.
Rep. Michael Rulli (OH) introduced the PEAT Act, which would amend the Public Health Service Act to prohibit treating a product as a biologic based solely on the presence of a protein that is an inactive component.
FDA has said it intends to issue draft guidance on DTE, but the guidance has not yet been released.
The ask
Read APC’s position in full
Download the issue brief, letters to FDA and citizen petition for the full details behind APC’s position.
The latest from APC
APC has been tracking FDA’s DTE decision since the start. Follow the story from FDA’s first notice to the latest developments.
For compounders
Many patients won’t know about FDA’s decision until it affects them directly. A brief conversation at pickup or during a medication review can make a real difference, and patient documentation supports both continuity of care and APC’s advocacy.
Talk with your DTE patients. Help them document why synthetic options weren’t enough. Point them to compounding.com/thyroid to share their story and send a message to FDA.
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