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Lexicon
Lexicon

ACTH 1-39

Full-length corticotropin, 39 amino acids, the pacemaker of the adrenal axis

5 min read 9 sources

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ACTH 1-39 vial with white powder and the black TPD label on a white podium, next to it a large molecule model of blue, light blue and white spheres in a bright lab
Compound approved · as corticotropin since 1950

Summary

At a glance

Sources checked on 26 Oct 2026

Length
39 amino acids

the complete hormone, cut from the precursor POMC7

Half-life in blood
~15 minutes

after intravenous dosing, according to the US label6

Cortisol response at low ACTH already
~80 %

of the maximum rise at 50 to 60 ng/l ACTH in blood, healthy men1

First approval as corticotropin
1,950

according to ChEMBL, today mainly as a depot product9

  • ACTH 1-39 is adrenocorticotropic hormone at full length, 39 amino acids from the precursor POMC. Via the receptor MC2R it controls cortisol production in the adrenal cortex.75
  • The dose-response curve is steep: in a study in healthy men ACTH levels of 50 to 60 ng/l already triggered almost 80 percent of the maximum cortisol rise.1
  • ACTH disappears quickly from the blood, the half-life is about 15 minutes. The body's own ACTH and cortisol come in pulses with a daily rhythm.62
  • Corticotropin is approved as a depot product. Its side effects are essentially those of raised cortisol, such as high blood pressure, fluid retention and more infections.69
  • There are no controlled data on repeated use as a research compound. Everything here is the state of research, not a recommendation.8
Profile

Updated June 2026

Type
Peptide hormone, 39 amino acids

POMC cleavage product

Target receptor
MC2R

adrenal cortex, melanocortin family

Axis
Hypothalamic-pituitary-adrenal

HPA

Evidence
Endocrine human data yes

research use thin

Sizes
5 mg

1 size in the shop

Contents 15 sections
  1. At a glance
  2. What is ACTH 1-39?
  3. How it works
  4. What you need
  5. Reconstitution
  6. Injection
  7. Dosing
  8. What the research shows
  9. Research status
  10. Side effects
  11. Storage
  12. Related compounds
  13. FAQ
  14. Glossary
  15. Sources

What is ACTH 1-39?

ACTH 1-39 is adrenocorticotropic hormone in its full length - 39 amino acids, cleaved from the large precursor protein POMC (proopiomelanocortin) in the pituitary. So it is not a synthetic fragment but the complete endogenous signaling molecule that drives the adrenal glands.

Clinically, ACTH exists as an approved product (Acthar Gel, repository corticotropin) - used for infantile spasms and acute MS flares. Diagnostically, the HPA axis is usually tested with short synthetic analogs instead (ACTH 1-24 / cosyntropin), not the full-length peptide. That is an important distinction to keep in mind.

Here ACTH 1-39 is framed strictly as a research substance. This information serves research and educational purposes only. No medical recommendations.

Comparison

Melanocortins in the lexicon

ACTH belongs to the melanocortin family. Which entries address which melanocortin receptors, as stated in the TPD lexicon. Tap a card to open its entry.

Full hormone, adrenal gland ACTH 1-39 MC1R MC2R MC4R 2 of 3 receptors
MC1R agonist, pigment Melanotan 1 MC1R MC2R MC4R 1 of 3 receptors Melanocortin agonist Melanotan II MC1R MC2R MC4R 2 of 3 receptors End piece of alpha-MSH KPV MC1R MC2R MC4R 0 of 3 receptors

Simplified: only ACTH addresses MC2R and so controls the adrenal gland. The melanotans act on pigment and appetite, KPV without receptor action. 95

How it works

ACTH binds the melanocortin-2 receptor (MC2R) on the cells of the adrenal cortex. MC2R is the only melanocortin receptor that responds exclusively to ACTH - and it needs an additional small accessory protein (MRAP) to function at all.

Binding activates adenylyl cyclase via the Gs protein, cAMP rises, protein kinase A fires up. This drives cortisol synthesis in the zona fasciculata - that is the main pathway. Acutely, ACTH can also nudge aldosterone production in the zona glomerulosa, though aldosterone is primarily governed by angiotensin and potassium.

Through its first amino acids, ACTH shares kinship with the melanocyte-stimulating hormones (MSH) and can also engage MC1R - hence the known pigment component. In the body the whole thing runs as a pulsatile, time-of-day-dependent signal with a short half-life of roughly 10 to 20 minutes.

Where it acts

Where ACTH acts

Tap a point or a card. Colour = receptor, grey = observed.

  1. Adrenal gland (on the kidney)

    MC2R activated, cortisol and briefly aldosterone rise1

    MC2R
  2. Pituitary gland

    Releases ACTH in pulses with a daily rhythm, high cortisol brakes release2

    Observed in trials
  3. Circulation

    Rise in blood pressure, salt and water retention, potassium falls6

    Observed in trials
  4. Skin

    According to the label also binds melanocortin receptors, acne and skin changes as side effects6

    Observed in trials

Targets in the ChEMBL database9

Compound CHEMBL1201610: one recorded mechanism, agonist with direct binding to the human receptor.

ACTH receptor (melanocortin 2 receptor)
Gene
MC2R
UniProt
Q01718
ChEMBL
CHEMBL1965
Action
Agonist, direct binding
Domed layer of transparent cells with blue docking sites where blue molecule models made of many spheres dock and light up
ACTH docks onto MC2R of the adrenal cortex. Symbolic image.

What you need

Before you start, have everything ready:

Supplies

5 things, numbered as in the picture

Tick off what you already have. Vial and BAC water are our real shop photos at the same size.

ACTH 1-39 vial and bacteriostatic water at the same size with the dark TPD label and blue caps, next to them two insulin syringes, two alcohol swabs and a sharps container with a blue lid

  1. ACTH 1-39 vial

    The ACTH 1-39 vial with the freeze-dried powder

    In the shop

  2. Bacteriostatic water

    Bacteriostatic water for reconstitution

    In the shop

  3. U-100 insulin syringes

    U-100 insulin syringes for administration

    Amazon (opens a new tab)

  4. Alcohol swabs

    Alcohol swabs for the vial cap and the skin site

    Amazon (opens a new tab)

  5. Sharps container

    A sealable container for used needles

As an Amazon associate we earn from qualifying purchases. Links open Amazon - no extra cost for you.

Reconstitution

The powder is dissolved with bacteriostatic water. How much water you use determines the concentration and therefore how many units you draw on the insulin syringe.

Use the peptide calculator for exactly this: pick vial size and water volume. For ACTH 1-39 it deliberately shows no dose steps, only the concentration, because there is no protocol for repeated use. Example: a 5mg vial with 2ml water gives 2.5mg per ml, 0.25mg is then 10 units, 0.05mg 2 units on the U-100 syringe. Aqueous ACTH acts fast and short, which sets it apart from depot preparations.

Step by step

Dissolving the powder

Four steps, the same for every vial size.

  1. 1Wipe the cap

    Clean the rubber stopper with an alcohol swab.

  2. 2Add BAC water

    Just add it, it does not matter if it hits the powder directly.

  3. 3Swirl or shake

    Until everything has dissolved, both are fine.

  4. 4Draw up

    With the U-100 insulin syringe.

Less water higher concentration fewer units on the syringe Example: 5 mg + 2 ml = 2.5 mg/ml

Injection

The injection is subcutaneous, into the fat layer under the skin. Common spots are the abdomen (keep about two finger-widths clear of the navel), the front and the inner side of the thigh, or the back of the upper arm.

The short version:

Injection

Where and at what angle

Pick a spot or switch the angle. Subcutaneous means: into the fat layer, not the muscle.

Rotate the spot each time, never the same one twice in a row.

90°More fat under the skin

Rule of thumb: where there is more fat under the skin, insert straight at 90 degrees. In lean people with little fat, 45 degrees, so the needle stays in the fat layer. Simplified diagram.

  1. Clean the spot with an alcohol swab and let it dry

  2. Pinch up a small fold of skin

  3. Insert the needle: at 90 degrees where there is more fat under the skin, at 45 degrees in lean people with little fat

  4. Inject slowly, wait a moment, then withdraw

  5. Put the needle straight into the sharps container

ACTH 1-39 is only classed as a single dose here (see Dosing), so rotating sites does not apply.

Dosing

Dosing

Dosing, titration and syringe

Loading the dosing information …

  • Getting started and stepping up, drawn as a staircase
  • Units on the U-100 syringe for every step
  • How long one vial lasts

What the research shows

The physiology of ACTH has been well described for decades. Reviews of the HPA axis show that ACTH and cortisol are released in pulsatile, time-of-day-dependent waves and that this rhythm pattern matters more for the effect than a constant level (Lightman et al. 2020).

At the receptor level, MC2R as the ACTH-specific switch and its dependence on the accessory protein MRAP are well documented (Endotext, ACTH Action on the Adrenals). Diagnostically, the ACTH stimulation test with cosyntropin is established, including its known pitfalls around interpretation and thresholds (Burgos et al. 2019). For the full-length peptide itself there is a dose-response study in healthy men: subcutaneously, even 5mcg of synthetic ACTH 1-39 raised cortisol and aldosterone clearly. The curve is very steep at first (Oelkers et al. 1988).

What is missing: controlled data on ACTH 1-39 as a repeatedly subcutaneously applied research substance outside the approved indications. Endocrinology knows the hormone, but what is practiced in the research scene is not what was studied. Stay sober here.

Study results

What the trials measured

Interactive: switch tabs, tap points, show or hide arms. Arms are named relative to each other, no dosing advice.

How strongly cortisol rises with little ACTH1

Share of the maximum cortisol rise within the first hour, nine healthy men

ACTH in blood 50 to 60 ng/l1 compared with levels above 300 ng/l
ACTH 1-39 under the skin 80%

Almost 80 percent according to the abstract. Synthetic human ACTH 1-39 in increasing amounts under the skin, the highest study dose was 30 mcg. Even small amounts clearly raised cortisol, aldosterone and 18-hydroxycorticosterone, the curve is very steep at first.

Glass model of a kidney with vessels and a frosted adrenal gland on top, on a stainless steel cart in a bright lab
The adrenal gland sits on top of the kidney and makes cortisol. Symbolic image.

Research status

Where the research stands

Corticotropin has been approved since 1950. On ClinicalTrials.gov 223 trials name corticotropin, many of them only use it as a test of the adrenal gland. Shown are trials that test ACTH as a treatment, including a phase 3 trial with synthetic ACTH 1-39 as a gel. As of 26 Oct 2026. 8

  1. Preclinical Principle: activation of MC2R in the adrenal cortex
  2. Phase 1 no registered trial
  3. Phase 2 no registered trial
  4. Phase 3 6 trials, 3 completed, 1 stopped early
  5. Approval as corticotropin since 1950
546 participants in phase 3 Planned figures for running trials Approved: ChEMBL lists corticotropin with phase 4 as the highest phase and first approval in 1950. In the US it is available as a depot product for intramuscular or subcutaneous use. Synthetic ACTH 1-39 as a separate product is still in phase 3.9
Show all 6 phase 3 trials on a timelineHide timeline 3 completed 2 running 1 stopped early 0 with results
Phase 3

Bar: start to primary endpoint (planned for running trials). Green = completed, blue = progress until 26 Oct 2026, grey = stopped early.

Side effects

ACTH does not act directly but ramps up the body's own cortisol production - so its side effects are essentially those of elevated glucocorticoid levels. Known from the Acthar data: fluid and sodium retention, rising blood pressure, mood and sleep changes, elevated blood sugar, increased appetite.

Prolonged or high use can affect the HPA axis and dampen the immune system. Through the MSH kinship (MC1R), pigment changes are conceivable. At the injection site, the usual local reactions.

Anyone with high blood pressure, a tendency toward diabetes, or a known adrenal issue should view ACTH especially critically. When in doubt: stay low or skip it.

Tolerability

Side effects of the depot product

The only table with frequencies in the label comes from infants on a depot product. It shows how cortisol-typical side effects increase with the amount. There was no placebo group.

20 of 100 Depot, recommended regimen
46 of 100 Depot, higher regimen
Event Depot, recommended regimenDepot, higher regimen
Infections6 20%46%
Cushingoid appearance6 3%22%
High blood pressure6 11%19%
Irritability6 7%19%
Acne6 0%14%

For adults the label lists after approval among others fluid retention, insomnia, headache and raised blood glucose. Longer use can suppress the body's own hormone axis, after stopping adrenal insufficiency may follow.6

Storage

Store the undissolved powder cool and dark. Once mixed, it keeps for at least 4 to 6 months in the fridge (2 to 8 °C).

Shelf life

How long it keeps

Undissolved (powder) Cool and dark

Keep the undissolved powder cool and away from light.

Dissolved (mixed) Fridge, 2 to 8 degrees

Keeps for at least 4 to 6 months.

  • Keep it dark
  • Dissolved: 2 to 8 degrees
  • Note the mixing date on the vial
Nine vials with white powder and blue caps in the door shelf of a bright fridge
Powder cool and dark, once dissolved into the fridge (2 to 8 degrees), stable there for at least 4 to 6 months. Symbolic image.

Related

Related compounds

A different path: all in the TPD lexicon.

ACTH 1-39
Melanotan 1 Same family, acts on tanning Melanotan II Same family, tanning and appetite KPV End piece of alpha-MSH, which shares its first building blocks with ACTH

FAQ

Common questions about ACTH 1-39

Short answers, each backed by the sources below.

How does ACTH 1-39 differ from the short test peptide?

ACTH 1-39 is the complete hormone with 39 amino acids. To test the adrenal gland, clinics mostly use a shorter synthetic piece with the first 24 amino acids. With this test the results depend on time of day, assay and sample type.73

Is ACTH approved?

Yes, as corticotropin. ChEMBL lists its first approval in 1950. In the US it is approved as a depot product, among other uses for infantile spasms and acute relapses of multiple sclerosis. Synthetic ACTH 1-39 as a gel is in a phase 3 trial.968

How strongly does even a little ACTH act?

Very strongly. In a study in nine healthy men participants received increasing amounts of synthetic ACTH 1-39 under the skin, up to the highest study dose of 30 mcg. ACTH levels of just 50 to 60 ng/l in blood triggered almost 80 percent of the maximum cortisol rise.1

Why does the rhythm matter?

ACTH and cortisol come in pulses of varying height over the day. According to a review the body needs exactly this pattern. If it is overridden by steady dosing, metabolism, mood and thinking can be affected.2

Which side effects are known?

Essentially those of raised cortisol: high blood pressure, salt and water retention, falling potassium, raised blood glucose, more infections and mood changes. Longer use can cause Cushing's syndrome and suppress the body's own hormone axis, after stopping adrenal insufficiency may follow.6

How long does ACTH act?

Dissolved ACTH disappears quickly from the blood, according to the label the half-life is about 15 minutes. According to the label the pharmacokinetics of the depot product have not been adequately characterised.6

Glossary

Terms explained briefly

Dotted words in the text open these explanations directly.

Aldosterone
Hormone of the adrenal cortex that regulates salt and water balance.
Cortisol
Stress hormone of the adrenal cortex. It raises blood glucose and dampens inflammation.
Cosyntropin
Synthetic ACTH piece with the first 24 amino acids, used to test the adrenal gland.
HPA axis
Hormone axis of hypothalamus, pituitary and adrenal gland. It controls cortisol release.
Lyophilisate
Freeze-dried powder. Without water a peptide keeps much longer.
MC2R
Melanocortin 2 receptor on cells of the adrenal cortex. It responds only to ACTH.
MRAP
Small helper protein without which MC2R does not reach the cell surface and does not work.
POMC
Proopiomelanocortin: a large precursor protein in the pituitary from which ACTH and the MSH hormones are cut.
Pulsatile
Released in bursts rather than evenly. ACTH and cortisol come in pulses whose height varies over the day.
Zona fasciculata
Middle layer of the adrenal cortex where mainly cortisol is made.

Evidence

Sources

Show all 9 sourcesHide sources 3 Studies1 Trial registry5 Database checked 26 Oct 2026

Studies

  1. Dose-response of synthetic ACTH 1-39 in healthy men

    Oelkers et al., Journal of Clinical Endocrinology & Metabolism, 1988

    DOI 10.1210/jcem-66-1-181 PMID 2826525
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  2. Review: pulses and rhythm of ACTH and cortisol

    Lightman et al., Endocrine Reviews, 2020

    DOI 10.1210/endrev/bnaa002 PMID 32060528
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  3. Pitfalls of the ACTH test of the adrenal gland

    Burgos et al., Current Opinion in Endocrinology, Diabetes and Obesity, 2019

    DOI 10.1097/MED.0000000000000473 PMID 30855285
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed

Trial registry

  1. Trials on corticotropin on ClinicalTrials.gov

    ClinicalTrials.gov, U.S. National Library of Medicine

    Checked 26 Oct 2026 via ClinicalTrials.gov API v2

Database

  1. Physiology of ACTH (textbook chapter)

    Yamamoto und Kaur, StatPearls, NCBI Bookshelf

    PMID 29763207
    Checked 26 Oct 2026 via PubMed
  2. ACTH action on the adrenal glands (textbook chapter)

    Angelousi et al., Endotext, NCBI Bookshelf

    PMID 25905342
    Checked 26 Oct 2026 via PubMed
  3. US prescribing information for depot corticotropin

    DailyMed, U.S. National Library of Medicine (Stand 10/2026)

    Checked 26 Oct 2026 via DailyMed
  4. Precursor POMC with the ACTH section in UniProt

    UniProt (P01189, Corticotropin Position 138 bis 176)

    Checked 26 Oct 2026 via UniProt
  5. Corticotropin in ChEMBL (mechanism, approval)

    ChEMBL, EMBL-EBI (CHEMBL1201610)

    Checked 26 Oct 2026 via ChEMBL

In the shop

ACTH 1-39 in the catalog

Sizes, prices and shipping times are on the product page.

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