A Phase 3 Open-label Extension Study to Evaluate the Long-term Safety and Tolerability of Chronocort in the Treatment of Participants Aged 16 Years and Over with Congenital Adrenal Hyperplasia.

Congenital adrenal hyperplasia (CAH) is most commonly caused by 21-hydroxylase deficiency that results in cortisol deficiency, with or without aldosterone deficiency, and androgen excess. Patients are currently treated with glucocorticoid replacement therapy, but immediate-release formulations fail to replicate the natural cortisol circadian rhythm, resulting in patients being poorly controlled. Chronocort(RegisteredTM) is a modified-release oral formulation of hydrocortisone, and it is designed to closely mimic the normal serum levels of the endogenous cortisol circadian rhythm, offering the prospect of an improved treatment outcome. This extension study is designed to allow participants who have taken part in previous Chronocortstudies (France and US sites in study DIUR-006 and all sites apart from Turkey in study DIUR-014) to either continue Chronocort treatment (if they received Chronocort in the feeder study) or switch to Chronocort treatment (if they received standard care in the feeder study). Participants who entered the Phase 2 DIUR-003 and Phase 3 DIUR-005 studies were given the option to enter the Phase 3 DIUR-006 safety follow-on study. Participants who remain in the DIUR-006 safety follow-on study from France and US will be given the option to enter this DIUR-015 study. Participants who have completed the DIUR-014 Phase 3 study will also be given the option to enter this DIUR-015 study (excluding patients from sites in Turkey). The DIUR-014 study is blinded so it will not be known whether the participant received Chronocort or immediate-release hydrocortisone (IRHC) during this study. These participants will be given the opportunity to start Chronocort at the same daily dose as that taken during the DIUR-014 study (either as Chronocort or as IRHC), split as approximately [?] to [?] of the total daily dose in the morning on waking and [?] to [?] of the total daily dose at night just prior to bed. These participants will attend a dose titration visit at Week 6, with a second optional dose titration visit at Week 12. It is noted that participants entering this DIUR-015 study will have differing pre-Chronocort baselines.