CalcMyPeptide
Clinical / PharmaceuticalAlso known as: Cosyntropin, Synacthen, ACTH 1-24, Tetracosactrin

Tetracosactide

Tetracosactide (Cosyntropin) is the pure, synthetic recreation of the first 24 amino acids of the human Adrenocorticotropic Hormone (ACTH)—the exact sequence holding 100% of the molecule's biological firepower. It is the absolute clinical standard for aggressive diagnostic interrogation of the adrenal glands, utilized instantly in emergency and endocrine settings to forcefully test the maximum acute cortisol-producing capacity of a failing adrenal cortex.

Reviewed by CalcMyPeptide Editorial Team
Last updated: April 2026Evidence: High1 peer-reviewed citation

Quick Stats

Half-Life~15-20 minutes
Dose Range250 mcg IV/IM (diagnostic)
FrequencySingle dose (ACTH stimulation test)
Vial SizesN/A (oral)
BioavailabilityIntravenous or intramuscular injection
Year Developed1960s

Scientific Data

Molecular Formula
C136H210N40O31S
Molecular Weight
2933.5 g/mol
CAS Number
PubChem ID

Mechanism of Action

Tetracosactide (also known as cosyntropin or Synacthen) is a synthetic peptide consisting of the first 24 amino acids of adrenocorticotropic hormone (ACTH). The full human ACTH has 39 amino acids, but biological activity resides entirely in the N-terminal 24 sequence.

Tetracosactide stimulates the adrenal cortex to rapidly produce cortisol and other corticosteroids. It is primarily used clinically as a rapid diagnostic test (the Synacthen Test) for adrenal insufficiency. Unlike long-term corticosteroid therapy, it relies on the body's own adrenal steroidogenic pathways.

Source: PMID: 6765449

Background & History

Tetracosactide (cosyntropin/Synacthen) is an essential diagnostic tool in endocrinology. The ACTH stimulation test has been the gold standard for diagnosing adrenal insufficiency for over 50 years. The short Synacthen test takes only 1 hour and can be performed in outpatient settings. Depot formulations (Synacthen Depot) have also been used therapeutically for infantile spasms and inflammatory conditions in various countries.

Research Use Cases

  • Adrenal insufficiency diagnosis
  • ACTH stimulation test
  • Infantile spasms (depot form)
  • Therapeutic use in inflammatory conditions

Dosing Protocol

Typical Dose250 mcg IV/IM (diagnostic)
FrequencySingle dose (ACTH stimulation test)
Half-Life0.25 hours

Dosing Protocols

Diagnostic (Synacthen Test)

Dose
250 mcg
Frequency
Single IV or IM dose
Note: FDA-approved diagnostic standard for adrenal insufficiency.

Therapeutic (Rare)

Dose
1 mg Depot
Frequency
Varies
Note: Used rarely in cases like infantile spasms or MS exacerbations where endogenous cortisoid release is preferred over oral steroids.

Body-Weight Dosing Reference

Estimated doses extrapolated from the published research range of 250250 mcg/day (referenced to 70 kg / 154 lb). These are approximations — consult a qualified healthcare provider for personalised guidance.

WeightLowTargetHigh
120 lb(54 kg)193 mcg193 mcg193 mcg
140 lb(63 kg)225 mcg225 mcg225 mcg
160 lb(73 kg)261 mcg261 mcg261 mcg
180 lb(82 kg)293 mcg293 mcg293 mcg
200 lb(91 kg)325 mcg325 mcg325 mcg
220 lb(100 kg)357 mcg357 mcg357 mcg
250 lb(113 kg)404 mcg404 mcg404 mcg

💉 For exact syringe units based on your vial concentration, use the Tetracosactide Reconstitution Calculator →

Administration

Route
IV or IM injection
Timing
Morning (diagnostic test).
Fasting Required?
No — food timing not critical

Expected Timeline

30-60 minutes
Diagnostic blood draw for peak cortisol response. Cortisol should rise above 18-20 μg/dL.

Who Is It For?

Adrenal Function Testing

High

The gold-standard diagnostic tool for Addison's disease and HPA axis evaluation.

Safety & Considerations

FDA-approved. Mostly used in supervised clinical settings for single-dose diagnosis. Therapeutic use carries risks similar to chronic corticosteroid exposure.

Regulatory & Legal Status

FDA Status (US)
Research Only
WADA Status (2026)
Not Listed

Not currently on the WADA 2026 Prohibited List. Policies may change — verify before competition.

Classification

Research Chemical

US Compounding: Not eligible / not available

⚠️ This information is for educational purposes only and may not reflect the most current regulatory updates. Always verify with official FDA, WADA, and jurisdiction-specific sources before use.

Interactions & Contraindications

Exogenous corticosteroids will blunt the cortisol response and should be withheld before testing. Dexamethasone does not cross-react with cortisol assays.

Dosing Quick Reference

Tetracosactide— Dosing Guide
Dose Range
250 mcg IV/IM (diagnostic)
Half-Life
0.25 hours
Frequency
Single dose (ACTH stimulation test)
Route
Oral
Clinical / Pharmaceuticalcalcmypeptide.com

Frequently Asked Questions

What is the Synacthen test?
It is a diagnostic test where tetracosactide (synthetic ACTH) is injected, and your cortisol is measured 30-60 minutes later. If cortisol does not rise adequately, it indicates primary adrenal insufficiency (Addison's disease).

References

  1. Dorin RI et al. "The standard short Synacthen test in adrenal insufficiency".” Annals of Internal Medicine (2003). PMID: 12860585

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