Comparison of Chronocort® With Standard Glucocorticoid Therapy in Patients With Congenital Adrenal Hyperplasia

This study is a parallel arm, randomised, open-label study, including dose titration and admissions for four overnight stays for 24-hour endocrine profiles. It will compare the efficacy, safety and tolerability of Chronocort® with standard glucocorticoid replacement therapy in the treatment of congenital adrenal hyperplasia (CAH) over a treatment period of 6 months. Dose titration decisions in both treatment groups will be made by a central independent physician, blinded to the treatment arm, using information generated from the 24-hour endocrine profiles. Each treatment arm will be subject to the same titration rules throughout the study, ensuring that opportunities for optimisation and control of androgens are the same in both groups.

At baseline, subjects will be admitted overnight for a 24-hour endocrine profile whilst on their standard therapy. Subjects will attend the study site in the morning and have 17-hydroxyprogesterone (17-OHP) and androstenedione (A4) levels assessed at 15:00, 17:00, 19:00, 21:00, 23:00, 01:00, 03:00, 05:00, 07:00, 09:00, 11:00, 13:00 and 15:00. Safety laboratory tests, a DEXA scan for body composition, and height, weight and waist circumference will be recorded. Subjects will then be randomised to Chronocort® or to continue on their standard care. Randomisation will be stratified by baseline treatment:

1. hydrocortisone only or
2. prednisone or prednisolone, alone or in combination with hydrocortisone
3. dexamethasone only or in combination with any other glucorticoid

The initial dose setting at the start of the Chronocort® treatment will be based on hydrocortisone dose equivalent of baseline therapy in accordance with standard clinical practice. Further dose refinement/titration will be conducted in both treatment groups as necessary after 4 weeks and 12 weeks using a standardised titration algorithm after the subject has been re-admitted for further 24-hour endocrine profiles. Safety endpoints will also be measured at the 07:00 morning sample of each 24-hour profile assessment day. The decision to change doses in both treatment groups will be made by a central independent blinded physician, with the actual change in dose then being made by the local investigator looking after the subject. At 6 months, all the baseline tests will be repeated (including the 24-hour profile). All subjects may then continue on Chronocort®, whatever their randomised treatment, as part of an open-label extension study (to be conducted under a separate protocol). Stress doses of hydrocortisone will be given throughout the study for intercurrent illnesses as medically indicated according to "sick day rules".

Eligibility Criteria:
Inclusion Criteria:

1. Known CAH due to 21-hydroxylase deficiency (classic CAH) diagnosed in childhood with documented (at any time) elevated 17-OHP and/or A4 and currently treated with hydrocortisone, prednisone, prednisolone or dexamethasone (or a combination of the aforementioned glucocorticoids) on a stable glucocorticoid therapy for a minimum of 6 months.
2. Provision of signed written informed consent.
3. Non-pregnant, non-lactating females who are post menopausal, naturally or surgically sterile, or of childbearing potential with a negative urinary pregnancy test and using a medically acceptable method of contraception.
4. Plasma renin activity (PRA) less than 1.5 times the upper limit of normal (ULN) at screening or within 3 months prior to screening, except in subjects who have been diagnosed with hypertension where the renin is not being used to monitor fludrocortisone replacement.
5. Plasma renin activity (PRA) less than 1.5 times the upper limit of normal (ULN) at screening or within 3 months prior to screening, except in subjects who have been diagnosed with hypertension where the renin is not being used to monitor fludrocortisone replacement.

Exclusion Criteria:

1. Co-morbid condition requiring daily administration of a medication (or consumption of any material) that interferes with the metabolism of glucocorticoids.
2. Clinical or biochemical evidence of hepatic or renal disease. Creatinine over twice the ULN or elevated liver function tests (ALT or AST \>2 times the ULN).
3. Subjects on regular daily inhaled, topical, nasal or oral steroids for any indication other than CAH.
4. Subjects with any other significant medical or psychiatric conditions that in the opinion of the investigator would preclude participation in the trial.
5. History of malignancy (other than basal cell carcinoma successfully treated \>6 months prior to entry into the study).
6. Participation in another clinical trial of an investigational or licensed drug or device within the 3 months prior to inclusion in this study.
7. Subjects with a history of bilateral adrenalectomy.
8. Subjects having previously been exposed to Chronocort®.
9. Subjects unable to comply with the requirements of the protocol.