Corticotropin is a polypeptide hormone produced and secreted by the pituitary gland. Corticotropin acts through the stimulation of cell surface the adrenocorticotropic hormone (ACTH) receptors, which are primarily located on the adrenocortical cells. Corticotropin stimulates the cortex of the adrenal gland and boosts the synthesis of corticosteroids, mainly glucocorticoids but also sex steroids (androgens). Corticotropin is indicated as monotherapy for the treatment of exacerbations of multiple sclerosis in adults and infantile spasms in infants and children under 2 years of age. Controlled clinical trials have shown Corticotropin to be effective in speeding the resolution of acute exacerbations of multiple sclerosis. However, there is no evidence that it affects the ultimate outcome or natural history of the disease. The mechanism of action of Corticotropin in the treatment of infantile spasms is unknown.