Shortage of Corticorelin Ovine Triflutate for Injection

The American Society of Health-System Pharmacists reports a shortage of injectable corticorelin ovine triflutate. This drug, brand name Acthrel, is used to diagnose Cushing's disease. Ferring is the only US supplier. It seems possible to me that this diagnostic reagent of ovine origin is being replaced with a human recombinant corticotropin-releasing hormone analog. Comments on this subject will be welcome.

In the normal course of events, corticotropin-releasing hormone from the paraventricular nucleus of the hypothalamus stimulates the pituitary gland to release adrenocorticotropic hormone (aka corticotropin), which in turn stimulates the release of cortisol from the adrenal glands. If a pituitary adenoma is present, it will also release ACTH, causing constant high levels of cortisol and the chronic, life-threatening form of the disease, Cushing's syndrome. The normal negative feedback mechanism that controls the blood level of cortisol doesn't affect the tumor. If a person has a pituitary adenoma, injection of corticorelin will cause additional ACTH and cortisol to be released despite the already high blood levels of cortisol. On the other hand, if the high levels of cortisol are the result of a tumor elsewhere in the body, the blood level of cortisol will not increase. Various cancers of the pancreas, ovaries, testes, etc., may then be sought out as the source of the problem.