Bone & endocrine

Cosyntropin (tetracosactide)

The active first 24 amino acids of ACTH, licensed mainly as the standard test for adrenal function.

Strong evidenceApproved drugAdd to compare

What it is

Cosyntropin, also called tetracosactide, is the first 24 amino acids of human adrenocorticotropic hormone - the entire biologically active portion. It is a diagnostic peptide: injected to see whether the adrenal glands respond by producing cortisol. A depot form is used as a short-term anti-inflammatory treatment in some countries.

How it works

1
Binds the melanocortin-2 (ACTH) receptor on cells of the adrenal cortex.
2
Stimulates cortisol synthesis and release within 30 to 60 minutes.
3
The size of the cortisol rise is the test result: a flat response indicates adrenal insufficiency.
4
Has no meaningful effect on mineralocorticoid pathways at diagnostic doses.
5
Depot formulations extend adrenal stimulation over days.

What it's studied for

Short ACTH stimulation (Synacthen) test for primary adrenal insufficiency

Assessment after long-term steroid therapy

Diagnostic work-up of suspected secondary adrenal insufficiency

Adrenal response in critical illness research

Short-term inflammatory conditions with the depot form

Reported and studied effects

A cortisol rise above the locally defined threshold in people with normal adrenal function
Detection of adrenal suppression after prolonged steroid use
No therapeutic effect beyond stimulating the adrenal cortex at diagnostic doses

Research protocol notes

Research context only

Research context only - diagnostic use. The standard short test uses 250 micrograms intramuscularly or intravenously with cortisol sampled at baseline, 30 and 60 minutes; low-dose variants use 1 microgram with more sensitive assays. Interpretation thresholds differ between assays and are set locally.

These figures are described so you can understand what researchers did. They are not a dose, a schedule, or a suggestion — and they are not a substitute for a doctor.

Possible side effects and contraindications

Safety profile

Possible side effects

Transient flushing
Nausea
Injection-site reactions
Hypersensitivity, including rare anaphylaxis
Fluid retention and electrolyte shifts with repeated depot use
Worsening of allergic or asthmatic symptoms rarely reported with depot use

Contraindications and cautions

Prior hypersensitivity to tetracosactide
Suspected adrenal crisis - treated immediately with steroid, not tested first
Active infection with depot use
Pregnancy only when clearly needed

A side-effect list is never complete, and these are not the only situations that warrant caution. Anything unexpected, or anything you are unsure about, should be discussed with a doctor before use.

Evidence assessment

Strong evidenceReplicated, large human trials

Replicated, large human trials

The reference standard for adrenal insufficiency diagnosis, with decades of comparative data against insulin tolerance and metyrapone testing.

References

References link to published literature, regulator pages or literature indexes. Where a link points to a search, it collects the peer-reviewed work on that molecule rather than a single study.

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