Tetracosactide (marketed under the brand name Synacthen) is a synthetic analogue of the naturally-occurring adrenocorticotrophic hormone (ACTH). In the normal situation, ACTH is released from the pituitary gland at the base of the brain. It acts on the adrenal glands to stimulate the production of steroid hormones (glucocorticoids. If the adrenal glands are healthy, a single injection of tetracosactide results in a rise in blood cortisol (hydrocortisone) concentrations in 30 minutes. If the adrenal glands appear not to be working then tetracosactide injection can be given to check whether the problem is due to diseased or damaged adrenals or due to lack of pituitary ACTH.
This medication is used for diagnostic purposes only (e.g. in short synacthen test. It is suitable for treatment of adrenal insufficiency of central origin.
As well as its legitimate medical applications, it has been widely reported that Synacthen has also been used as an illegal performance enhancing drug by professional cyclists. (Mentioned in Rough Ride by Paul Kimmage, p. 125 (tour 87 stage 14))