Dracut

Researchers are evaluating the safety and effectiveness of Armour Thyroid compared to synthetic T4 in adults with primary hypothyroidism who have been stable on synthetic T4 treatment. The study will also assess how well patients tolerate switching from synthetic T4 to Armour Thyroid. This trial is a Phase 23, randomized, double-blind study sponsored by AbbVie to compare these two thyroid hormone replacement therapies. Participants will be randomly assigned to receive either Armour Thyroid or to alternate between Armour Thyroid and synthetic T4 for up to 81 weeks. The treatments are oral capsules or tablets taken daily, with doses carefully converted from their stable synthetic T4 dose. The study includes a dose-conversion period where dosage adjustments may be made to maintain appropriate thyroid hormone levels. During the study, participants will have regular blood tests to measure thyroid-stimulating hormone TSH levels, including at week 55 to see who achieves a target TSH response. Researchers will also monitor for any adverse events throughout the study, which lasts up to about 90 weeks. Dose adjustments and safety data will be tracked closely to understand treatment effects and tolerability over time.