Tetracosactide is a synthetic analogue of the naturally occurring adrenocorticotrophic hormone (ACTH).

Pharmacology

In the normal situation, ACTH is released from the pituitary gland

Pituitary gland

In vertebrate anatomy the pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 g , in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity covered by a dural fold...

 at the base of the brain. It acts on the adrenal glands to stimulate the production of steroid hormones (glucocorticoid

Glucocorticoid

Glucocorticoids are a class of steroid hormones that bind to the glucocorticoid receptor , which is present in almost every vertebrate animal cell...

s). If the adrenal glands are healthy, a single injection of tetracosactide results in a rise in blood cortisol

Cortisol

Cortisol is a steroid hormone, more specifically a glucocorticoid, produced by the adrenal gland. It is released in response to stress and a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis; suppress the immune system; and aid in fat,...

 (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.

Uses

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.

It has been used in the treatment of spasm.