Tetracosactide

Tetracosactide is a synthetic peptide identical to cosyntropin (the first 24 amino acids of ACTH), but formulated as a depot preparation with zinc phosphate to provide sustained release and prolonged therapeutic effect. While cosyntropin is used primarily for short-duration diagnostic testing, tetracosactide depot is used therapeutically to stimulate the adrenal cortex to produce endogenous corticosteroids over an extended period.

The therapeutic rationale for tetracosactide depot differs from exogenous corticosteroid administration. By stimulating endogenous cortisol production, tetracosactide results in the secretion of multiple adrenal hormones including cortisol, corticosterone, aldosterone, and adrenal androgens. This broader hormonal profile may provide therapeutic effects not fully replicated by synthetic glucocorticoids alone. Additionally, some researchers have proposed that ACTH peptides may have direct anti-inflammatory and immunomodulatory effects independent of their action on the adrenal cortex, through melanocortin receptors expressed on immune cells.

The most important therapeutic application of tetracosactide depot is in the treatment of infantile spasms (West syndrome), a severe epileptic disorder of infancy. Multiple clinical trials have demonstrated that hormonal therapy (ACTH or tetracosactide depot) is more effective than vigabatrin for most causes of infantile spasms and is associated with better developmental outcomes. The UK Infantile Spasms Study (UKISS) showed tetracosactide depot was superior to vigabatrin in achieving spasm cessation and improving long-term neurodevelopmental outcomes.

Tetracosactide depot is also used for various inflammatory and autoimmune conditions in countries where it is available, including multiple sclerosis relapses, rheumatic disorders, and inflammatory bowel disease. Its use in these conditions is based on the same anti-inflammatory rationale as corticosteroid therapy, with some evidence suggesting additional benefits from the broader adrenal stimulation and direct melanocortin receptor effects.