Study to Determine if BHV-1300 is Effective and Safe in Adults With Graves' Disease

History of hyperthyroidism not caused by Graves' Disease (e.g., toxic adenoma or toxic multinodular goiter)

History of treatment with radioactive iodine or thyroid surgery.

Have received levothyroxine, desiccated thyroid extract, or T3 at any dose within six weeks of the Baseline/Day 1 Visit.

Thyroid storm, i.e. severe thyrotoxicosis with evidence of systemic decompensation (e.g., Burch-Wartkofsky Point Scale of ≥ 45 or Japanese Thyroid Association category 1 or 2, with accompanying manifestations including hyperpyrexia, tachycardia, arrhythmias, congestive heart failure, agitation, delirium, psychosis, stupor, and coma, as well as nausea, vomiting, diarrhea, or hepatic failure) within 6 weeks of Screening.