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.It has been used in the treatment of spasm. There is anecdotal evidence that athletes use the banned substance Synacthen because of its perceived benefit with its associated rise in cortisol.
In 2008, a study was released in the European Journal of Applied Physiology on the performance enhancing effects of synacthen. To test the performance-enhancing effects of Synacthen, eight trained cyclists completed two, 2-day exercise sessions separated by 7-10 days. On the first day of each 2-day exercise session, subjects received either Synacthen (0.25 mg, TX) or placebo (PLA) injection.
Performance was assessed by a 20-km time trial (TT) after a 90-min fatigue period on day 1 and without the fatiguing protocol on day 2. Plasma androgens and ACTH concentrations were measured during the exercise bouts as well as the rate of perceived exertion (RPE). Spot urines were analyzed for androgens and glucocorticoids quantification.
Basal plasma hormones did not differ significantly between PLA and TX groups before and 24 h after the IM injection (P > 0.05). After TX injection, ACTH peaked at 30 min and hormone profiles were significantly different compared to the PLA trial (P < 0.001). RPE increased significantly in both groups as the exercise sessions progressed (P < 0.001) but was not influenced by treatment. The time to completion of the TT was not affected on both days by Synacthen treatment.
In the present study, a single IM injection of synthetic ACTH did not improve either acute or subsequent cycling performance and did not influence perceived exertion. The investigated urinary hormones did not vary after treatment, reinforcing the difficulty for ACTH abuse detection.