Corticorelin

Corticorelin (Acthrel) was a real, FDA-approved diagnostic peptide hormone used to help pinpoint the cause of Cushing's syndrome — discontinued in 2020 over a manufacturing supply issue, with a documented real-world diagnostic-accuracy cost since it left the market.

What it was for

Corticorelin ovine triflutate is a synthetic corticotropin-releasing hormone (CRH) analog based on the ovine (sheep), not human, CRH sequence. It stimulates the pituitary to release ACTH, and was used purely diagnostically — in the "CRH stimulation test," and in petrosal sinus sampling protocols — to help distinguish whether excess ACTH driving a patient's Cushing's syndrome originates from a pituitary tumor or from an ectopic (non-pituitary) source, a genuinely important distinction for treatment planning.

Discontinued in 2020, and what that actually cost

The FDA approved corticorelin (as Acthrel, a biologic, BLA 020162) on 23 May 1996, manufactured solely by Ferring Pharmaceuticals. Ferring discontinued it in late September 2020, citing manufacturing sourcing issues rather than any safety or efficacy concern — FDA's biologics database now lists it as discontinued. This wasn't just a paperwork loss: a study examining petrosal sinus sampling during the resulting ovine-CRH shortage found that the procedure performed without CRH stimulation had meaningfully reduced sensitivity (85% vs. 97%) and specificity (57% vs. 71%) compared to the CRH-stimulated version — real, measurable diagnostic accuracy lost when the drug left the market.

A different molecule is now being developed

A company called Curatis has since begun redeveloping corticorelin — but for a different clinical use entirely, peritumoral brain edema from brain metastases (a steroid-sparing application), not the original CRH-stimulation-test diagnostic use. This is better understood as repositioning the same molecule for a new purpose than as "Acthrel coming back" — worth keeping those two things distinct if you encounter news about it.