Tetracosactide

How it works

It is a synthetic polypeptide corresponding to the first part of the ACTH molecule that stimulates the adrenal cortex, via melanocortin receptors, to synthesise and release corticosteroids, principally cortisol.

Prescribing in practice

• It is contraindicated in patients with a history of allergic disorders or previous hypersensitivity to ACTH preparations, as it can cause serious anaphylactic reactions, and facilities to treat anaphylaxis should be available.
• A normal cortisol response to the test does not exclude all forms of adrenal insufficiency, and results must be interpreted in clinical context.
• When used therapeutically it produces the same adverse effects as systemic corticosteroids and does not allow the precise control of an oral steroid dose.

Monitoring

For the diagnostic test, monitor plasma cortisol before and after administration and observe the patient for any hypersensitivity reaction.

Counselling the patient

• This is usually given as a one-off injection as part of a hormone test, with a blood sample taken before and after.
• Tell the clinician beforehand if you have any history of allergy or asthma.
• Report any rash, wheeze, swelling, or faintness after the injection.

Evidence & guidelines

Its use in assessing adrenocortical reserve is well established and forms the basis of the standard short synacthen test.