Cosyntropin (Cortrosyn)_Dosage, benefits & legal status
Also known as Cortrosyn, tetracosactide, tetracosactrin, Synacthen, Synacthen Depot, ACTH 1-24, ACTH fragment 1-24, tetracosactide acetate, tetracosactide hexaacetate, Vicotrope, Cosacthen
A synthetic copy of the active front section of ACTH, used for the ACTH stimulation test. Blood cortisol below about 18 mcg/dL at 30 or 60 minutes suggests adrenal insufficiency.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Cosyntropin (Cortrosyn)?
Plain language first. The technical label stays, but it never stands alone.Overview
When the adrenal glands cannot make enough cortisol (adrenal insufficiency), the diagnosis rests on a simple challenge: give the hormone signal and see whether cortisol rises. In the standard test, blood is drawn, 0.25 mg of cosyntropin is injected into a vein or muscle, and cortisol is measured again at 30 and 60 minutes; a value below 18 mcg/dL (500 nmol/L) suggests adrenal insufficiency, though newer, more specific cortisol tests use a lower cutoff of about 14 to 15 mcg/dL. The Endocrine Society prefers this 250 mcg test and finds the low-dose 1 mcg version no more accurate. Steroid medicines, spironolactone and estrogen can distort the result, so they are stopped beforehand.
Cosyntropin (INN tetracosactide) is a linear peptide identical to the first 24 of the 39 amino acids of ACTH, all natural L-residues with a free amino start and a free acid end. It activates the ACTH receptor (melanocortin 2 receptor, MC2R) on adrenal cortex cells to drive cortisol production; 0.25 mg stimulates the adrenal cortex maximally and to the same extent as 25 units of natural ACTH, with very little of natural ACTH's immunologic activity. In the US it is approved only as a diagnostic (Cortrosyn, NDA 016750, April 22, 1970); a zinc phosphate depot form, Synacthen Depot, is used as a treatment in the UK and other markets outside the US.
What it's used for
A one-time injection for the ACTH stimulation test, to check whether the adrenal glands respond by making cortisol. In the US it has no approved treatment use.
How does Cosyntropin (Cortrosyn) work?
What it does in the body, and where.Cosyntropin stands in for the pituitary's ACTH signal, so doctors can see whether the adrenal glands answer it.
- 01The normal signalThe pituitary releases ACTH to tell the adrenal cortex to make cortisol. Cosyntropin is ACTH's first 24 residues, the part that carries its activity; the label notes activity drops sharply in chains shorter than 20 residues.
- 02Switching on the adrenalIt binds the ACTH receptor (MC2R) on adrenal cortex cells and turns on steroid production: mainly cortisol, plus some aldosterone and adrenal androgens. A 0.25 mg dose drives the adrenal as hard as 25 units of natural ACTH.
- 03Reading the resultA healthy adrenal raises blood cortisol within 30 to 60 minutes. A weak rise, below about 18 mcg/dL (500 nmol/L), suggests the glands cannot respond. In the depot form, binding to zinc phosphate slows release so cortisol stays raised for about a day, the property that makes it usable as a treatment outside the US.
A schematic of the compound's mechanism, not a diagnostic image.
What else is it used for?
Each group carries its own evidence level.Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
Diagnosing adrenal insufficiency
FDA-approved- ReviewThe guideline prefers the standard 250 mcg test, with a peak cortisol below 500 nmol/L (18 mcg/dL) at 30 or 60 minutes pointing to primary adrenal insufficiency.
- ReviewThe 1 mcg test is no more accurate and is suggested only when the drug is in short supply.
Preventing headache after dural puncture
Early research- ReviewA 2013 Cochrane review of 10 trials (1,611 people) found IV cosyntropin reduced headache against placebo, with caution about small samples.
- Human trialIn one trial of 90 women after accidental dural puncture in childbirth, 1 mg IV cut headache to 33.3% against 68.9% with placebo.
Treating headache after dural puncture
tested-and-failed- Human trialESYBRECHE (NCT02813655), 46 women after childbirth: 1 mg tetracosactide IV against saline, with blood patch use as the endpoint; stopped for futility after an interim analysis.
Against an epidural blood patch
Early research- Human trial28 patients randomized: the blood patch gave better pain relief at day 1; results were similar right after treatment and at days 3 and 7.
Depot form (UK)
Clinical use- RegulatoryAfter 1 mg into muscle, blood levels of 200 to 300 pg/mL last 12 hours; cortisol peaks at 8 to 12 hours, stays raised to 24 hours and returns to baseline by about 36 to 48 hours.
Cosyntropin is often quoted as first approved in 2008, because both modern US labels print 'Initial U.S. Approval: 2008'; that date belongs to Sandoz's discontinued solution (NDA 022028), and Cortrosyn itself was approved on April 22, 1970. A June 2025 date has been reported for the current Cortrosyn label; Amphastar's label was updated on January 30, 2025. Synacthen Depot is not available in the US: it has never been FDA-approved, and no depot form is sold there. The US label gives no half-life at all; the UK label gives three phases of about 7 minutes, 37 minutes and 3 hours. The 1 mcg low-dose test is off-label, not the standard. Sampling times differ by label (30 and 60 minutes in the US, 30 minutes in the UK), and so do children's doses. Semax is often listed as 'ACTH 4-10', but its sequence is ACTH 4-7 (Met-Glu-His-Phe, cosyntropin's residues 4 to 7) followed by an added Pro-Gly-Pro; true ACTH 4-10 is MEHFRWG. Semax shares only those four residues and lacks the rest of the chain the adrenal response needs, so it has no adrenal-stimulating action. Molecular weights of 2934 and 2933.44 differ only by rounding.
The published record
Papers and trials about Cosyntropin (Cortrosyn)
379 papers tagged human · 292 not reviews or lab · 32 clinical trial publications
56 registered trials · 8 with posted results
Furthest stage reached: Approved in the US
Counted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count. 499 papers and 56 trials indexed in detail.
At a glance
Four things to know about Cosyntropin (Cortrosyn)
Evidence
FDA-approved
Category
Sexual and hormonal
Common vial
Varies
Half-life
About 7 minutes, 37 minutes and 3 hours across three phases (UK label)
How much, and do you cycle it?
The range, and whether you take breaks.0.25 mg (250 mcg) once, for the test (label), once per test. Single test dose FDA label
Given once for the test; in the US it is not used as a course of treatment.
How long does it stay in the body?
The half-life, and where the figure comes from.About 7 minutes, 37 minutes and 3 hours across three phases (UK label)clinical-guideline
From the UK label. After an injection into a vein, levels fall in three phases: about 7 minutes over the first hour, 37 minutes over the second, and 3 hours after that. It concentrates in the adrenals and kidneys (volume of distribution about 0.4 L/kg); serum enzymes break it into inactive fragments and then amino acids, and 95 to 100% of a labeled dose appears in urine within 24 hours. The depot form keeps blood levels at 200 to 300 pg/mL for 12 hours.
Source: Synacthen UK summary of product characteristics, section 5.2 (the US label gives no half-life)
You can compare this against the whole library to see where it sits.
How is it given?
Dosing context and source notes.Given in hospital from a prepared product, so there is nothing to mix.
Label dose: 0.25 mg per dose. Cortrosyn US prescribing information (2023), section 2
A single 0.25 mg (250 mcg) test dose into a vein or muscle for adults and children aged 2 to 17; 0.125 mg for children under 2. Blood cortisol is measured before the injection and exactly 30 and 60 minutes after; a value below 18 mcg/dL at either time suggests adrenal insufficiency, though cutoffs vary by assay. Glucocorticoids and spironolactone are stopped on the test day (longer for long-acting steroids), and estrogen-containing drugs 4 to 6 weeks before. Supplied as a 0.25 mg powder vial mixed with 1 mL of 0.9% saline to give 0.25 mg/mL, used once and the rest discarded. It is given by clinic or hospital staff as a single test, so there is no ongoing dose to calculate. The 1 mcg low-dose test is off-label. Outside the US, Synacthen Depot (1 mg/mL) is given into muscle only, never into a vein, at treatment doses such as 1 mg daily at first.
How do you store it?
Before mixing, and after.Follow the storage on the product label.
Cosyntropin (Cortrosyn) is supplied as a finished product, so its label sets the storage. Pens, prefilled syringes, implants, tablets and ready-made solutions are used as supplied. Kits that include a powder are mixed just before the dose and usually used straight away, not kept for weeks. Many injectable products go in the fridge and must not be frozen, while others are kept at room temperature, so check the pack or ask the pharmacist.
What are the side effects and cautions?
Known cautions and warnings for this compound.Solubility, computed: 42% charged residues, 38% hydrophobic. Water usually sufficient.
A first-pass rule from peptide manufacturers' guidance. It does not account for disulfide bridges, salt form or how the powder was dried, and it predicts what should be easy rather than what will happen in your vial.
Who should avoid it
- A past allergic reaction to cosyntropin or any ingredient, including anaphylaxis
- Asthma or other allergic disorders (UK label)
- Acute psychosis, infectious disease, peptic ulcer or refractory heart failure (UK label)
- Cushing's syndrome or adrenogenital syndrome, and use as a treatment for primary adrenal insufficiency (UK label)
Stop and get help
- Hives, swelling, wheezing or collapse after the injection: possible anaphylaxis
- A very slow or racing heartbeat
Common effects
- No adverse event rates are published: the US label lists post-approval reports only, with no trial table
- Reported: anaphylaxis, slow heart rate, fast heart rate, high blood pressure, swelling of the legs (peripheral edema) and rash
- ACTH 1-24 has very little of the immunologic activity of natural ACTH (US label)
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Cosyntropin (Cortrosyn) approved?
And where the numbers on this page come from.Yes. Cosyntropin (Cortrosyn) is FDA approved and available on prescription in the United States. It is also approved in the United Kingdom and Japan.
- Approval statusFDA-approved
- RouteInto a vein or muscle (single test dose)
- Checked16 October 2026
- Approved outside the USUnited Kingdom, Japan: In the UK, Synacthen 250 micrograms and Synacthen Depot 1 mg/mL are licensed to Atnahs Pharma UK (current license numbers dated June 25, 1998); the depot is used there as a treatment and for a 5-hour test. Japan lists tetracosactide under the trade name Cortrosyn. Synacthen also has national authorizations in EU countries (dates not established). Also FDA-approved in the US as a diagnostic since April 22, 1970.This does not change the United States position above.
- DoseFrom the drug label. The manufacturer tested this range and a regulator reviewed it.
- Vial sizeFrom what vendors typically list; not a recommendation.
- SourcesDrugs@FDA, NDA 016750 (Cortrosyn)Drugs@FDA, NDA 022028 (Sandoz cosyntropin solution)Cortrosyn US prescribing information (2023)openFDA drugsfda, cosyntropinFDA GSRS substance record, cosyntropin (UNII 72YY86EA29)Synacthen 250 micrograms UK summary of product characteristics (emc)Synacthen Depot 1 mg/mL UK summary of product characteristics (emc)Bornstein SR et al., Journal of Clinical Endocrinology and Metabolism 2016;101:364-389Mallinckrodt, Synacthen Depot IND (June 13, 2016)AdisInsight, tetracosactideClinicalTrials.gov, ESYBRECHE (NCT02813655)Basurto Ona X et al., Cochrane review CD001792 (2013)Riveros Perez E et al., Cureus 2020;12:e7052German Sport University Cologne, doping glossary: Synacthen
What has happened recently
The FDA approved Cortrosyn on April 22, 1970 (NDA 016750, a new molecular entity) as a diagnostic agent for screening adrenocortical insufficiency in adults and children; Amphastar now holds it. Sandoz's ready-made solution (NDA 022028) was approved on February 21, 2008 and is discontinued, and its 2008 date appears to be the source of the 'Initial U.S. Approval: 2008' line printed on both modern US labels. Sandoz also sells a generic powder (ANDA 202147, June 29, 2012), and the FDA has approved a veterinary version, Cosacthen, for testing dogs (NADA 141-576). Synacthen Depot, a zinc phosphate suspension used as a treatment in the UK, has never been approved in the US, and no depot form is FDA-approved or sold there in 2026; Mallinckrodt filed a US IND for it in Duchenne muscular dystrophy in 2016, and that program was later discontinued. It has received two FDA orphan designations for infantile spasms (outside the US the depot form is used for infantile spasms, as in the UK Infantile Spasms Study), one for Duchenne muscular dystrophy that was later withdrawn, and an EU orphan designation for Duchenne muscular dystrophy (dates not established). Tetracosactide is prohibited in sport at all times under WADA class S2.
Banned in drug-tested sport. Most research peptides are prohibited under WADA's S0 category, which covers any substance with no approval from any regulatory authority for human use. That means a compound can be banned without ever being named on the prohibited list. Check with your own anti-doping authority rather than assuming absence from the list means permitted.
You can compare this against the whole library, or read how to check a seller.
What else is like Cosyntropin (Cortrosyn)?
Others in Sexual and hormonal, side by side.If you're weighing Cosyntropin (Cortrosyn), it's worth reading PT-141 (Bremelanotide), Kisspeptin, and Gonadorelin (GnRH) in the same class.
A synthetic copy of the active front section of ACTH, used for the ACTH stimulation test. Blood cortisol below about 18 mcg/dL at 30 or 60 minutes suggests adrenal insufficiency.
- Dose
- 0.25 mg (250 mcg) once, for the test (label)
- How often
- Once per test
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- Dose
- 1.75 mg per dose
- How often
- As needed, before activity
A peptide that switches on natural sex-hormone signaling for libido and fertility.
- Dose
- 0.1 up to 0.2 mg per dose
- How often
- Daily in vendor protocols
A shot that keeps your own testosterone and fertility hormones going.
- Dose
- 0.1 up to 0.2 mg per dose (start low, increase slowly)
- How often
- 2-3x per week or more
Guides for this compound
- How to Reconstitute a Peptide
Mix peptide powder with bacteriostatic water, step by step.
- How to Read an Insulin Syringe
Read the units, convert to millilitres, and draw the exact dose.
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
Sources
- Drugs@FDA, NDA 016750 (Cortrosyn)(2023)Approved April 22, 1970 as a new molecular entity; held by Amphastar.
- Drugs@FDA, NDA 022028 (Sandoz cosyntropin solution)(2024)Approved February 21, 2008 as a Type 5 application (new formulation or manufacturer), now discontinued; the likely source of the 2008 date on the labels.
- Cortrosyn US prescribing information (2023)(2023)Indication, adult and pediatric doses, 18 mcg/dL cutoff; the first 24 of ACTH's 39 amino acids; 0.25 mg equals 25 units of natural ACTH; MW 2934; post-approval adverse reactions only.
- openFDA drugsfda, cosyntropin(2026)Four US applications, none for a depot or zinc form.
- FDA GSRS substance record, cosyntropin (UNII 72YY86EA29)(2026)Sequence SYSMEHFRWGKPVGKKRRPVKVYP, 24 residues, no modifications; CAS 16960-16-0; INN tetracosactide.
- Synacthen 250 micrograms UK summary of product characteristics (emc)(2026)Three-phase half-life of about 7 minutes, 37 minutes and 3 hours; 30-minute test criteria; UK contraindications and 30-minute observation.
- Synacthen Depot 1 mg/mL UK summary of product characteristics (emc)(2026)Zinc phosphate suspension, into muscle only; treatment doses; cortisol peaks at 8 to 12 hours and stays raised to 24 hours.
- Bornstein SR et al., Journal of Clinical Endocrinology and Metabolism 2016;101:364-389(2016)Endocrine Society guideline: standard 250 mcg test preferred; 1 mcg test only when supply is short; cutoff 500 nmol/L (18 mcg/dL).
- Mallinckrodt, Synacthen Depot IND (June 13, 2016)(2016)IND for Duchenne muscular dystrophy; Synacthen Depot has never been approved for use in patients in the US.
- AdisInsight, tetracosactide(2026)Duchenne muscular dystrophy development discontinued at phase 2.
- ClinicalTrials.gov, ESYBRECHE (NCT02813655)(2025)46 women with post-dural puncture headache after childbirth, 1 mg tetracosactide against saline: terminated for futility; published in Br J Anaesth 2025.
- Basurto Ona X et al., Cochrane review CD001792 (2013)(2013)10 trials, 1,611 people, 7 drugs: IV cosyntropin reduced headache after lumbar puncture against placebo, with caution about small samples.
- Riveros Perez E et al., Cureus 2020;12:e7052(2020)Cites Hakim 2010: 90 women after accidental dural puncture, headache 33.3% with 1 mg IV cosyntropin against 68.9% with placebo.
- German Sport University Cologne, doping glossary: Synacthen(2026)Corticotropins, including Synacthen, are prohibited at all times under WADA class S2.
Beyond these, 555 records are indexed. Browse the records