This is a non-randomized, open-label, single arm, self-controlled study of XP-8121 (levothyroxine sodium) to determine a target dose conversion factor from stably dosed oral levothyroxine to XP-8121 (levothyroxine sodium) in patients with hypothyroidism and to assess the safety and tolerability of XP-8121 (levothyroxine sodium) after once weekly subcutaneous injections. This study includes the following periods: Screening, Titration Period (2 to 8 weeks), and Maintenance Period (4 weeks). A pharmacokinetic substudy will be conducted for a subset of patients during the Maintenance Period. The study will conclude with an End of Maintenance Visit or Early Termination (ET) Visit.
This is a non-randomized, open-label, single arm, self-controlled study of XP-8121 (levothyroxine sodium) to determine a target dose conversion factor from stably dosed oral levothyroxine to XP-8121 (levothyroxine sodium) in patients with hypothyroidism and to assess the safety and tolerability of XP-8121(levothyroxine sodium) after once weekly subcutaneous injections. This study includes the following periods: Screening, Titration Period, and Maintenance Period. The study will conclude with an End of Maintenance Visit or Early Termination (ET) Visit.