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Muscle & performance

Primobolan E (Methenolone Enanthate)

The mild premium steroid - clean, dry gains with a low side effect profile.

1 min read 11 sources

To the product To the sources
Glass vial with pale yellow oil and a black TPD label on a white podium, next to it a glossy blue 3D steroid molecule with a long ester chain in a bright lab, symbolic image for methenolone enanthate
Older studies, none registered · not approvedLab tested in the shop

Summary

At a glance

Sources checked on 26 Oct 2026

Remissions in breast cancer
8 of 41

lasting more than 3 months, patients with metastatic breast cancer, study from 19753

Raised blood lipids
12 of 28

Women with breast cancer, reversed in every case after stopping4

Detectable in urine
40 days

new metabolite after one oral dose, one volunteer6

Exposed jaw bone (rat)
10 %

after zoledronic acid with methenolone enanthate, without it 75%7

On the registry
0 trials

no interventional trial on ClinicalTrials.gov, as of 26 Oct 202610

  • Methenolone enanthate is methenolone with a long enanthate ester. Methenolone is a derivative of DHT and in a comparison study bound to the androgen receptor less strongly than nandrolone but more strongly than testosterone.18
  • A 2025 structural study showed methenolone bound to GPR133, a receptor in the cell membrane through which DHT increased strength in muscle cells.2
  • Human data come mainly from older studies: in metastatic breast cancer metastases regressed in 8 of 41 patients, in anaemia 7 of 19 people responded.35
  • In 12 of 28 women blood lipids rose on methenolone enanthate and returned to normal in every case after stopping. One metabolite was detectable in urine for up to 40 days.46
  • The registry lists no trial and ChEMBL gives neither a phase nor an approval. Everything here is the state of research, not a recommendation.1011
Profile

Updated June 2026

How long does it stay in the body?

Share left after one dose, calculated with a half-life of ~6 days

Half-life ~6 days
After 12 days: 25 %
Day 6 · 50 %Day 12 · 25 %Day 18 · 12.5 %Day 30 · 3.1 %

Simplified model without an absorption phase, half-life from the TPD lexicon. The lexicon gives 5 to 7 days, we calculate with the middle.

Class
DHT derivative

long enanthate ester

Use
Intramuscular or subcutaneous

2x per week

Half-life
about 5-7 days
WADA
banned

anabolic

Sizes
2 sizes

100mg/ml, 200mg/ml

Contents 13 sections
  1. At a glance
  2. What is Primobolan?
  3. How it works
  4. Use and dosing
  5. What the research shows
  6. Research status
  7. Side effects
  8. Storage
  9. PCT / after coming off
  10. Related compounds
  11. FAQ
  12. Glossary
  13. Sources

What is Primobolan?

Primobolan E (Methenolone Enanthate) is a mild DHT derivative with a long enanthate ester. It is considered one of the "cleanest" injectable anabolics - no aromatization, low side effect profile, dry and well-retained gains. Historically methenolone was used for muscle wasting and anemia. It is expensive to source, hence priced accordingly.

This information is for research and educational purposes only. No medical advice.

Comparison

Methenolone and relatives

Another form of the same compound and related steroids at the same receptor, as described in the TPD lexicon. Tap a card to open its entry.

Methenolone, long ester Primobolan E (Methenolone Enanthate) AR
Oral methenolone Primobolan Oral (Methenolone Acetate) AR Another DHT derivative, same ester Masteron E (Drostanolone Enanthate) AR Nandrolone, long ester Deca (Nandrolone Decanoate) AR Testosterone, same ester Testosterone Enanthate AR

In a comparison study methenolone bound to the androgen receptor less strongly than nandrolone but more strongly than testosterone. 1

How it works

As a DHT derivative primobolan does not aromatize and causes no estrogen side effects. The anabolic effect is mild but very "clean" - no water retention, good definition. Primo does need a sufficient dose to be noticeable.

Where it acts

Where methenolone acted in studies

Tap a point or a card. Colour = target, grey = observed, partly in animal studies.

  1. Muscle cells

    Binds to the membrane receptor GPR133, through which DHT increased strength in muscle cells2

    GPR133
  2. Liver and blood lipids

    Blood lipids rose in 12 of 28 women, back to normal after stopping4

    Observed in trials
  3. Blood formation

    Response in 7 of 19 people with refractory anaemia5

    Observed in trials
  4. Jaw bone (rat)

    Less exposed bone after zoledronic acid (10 vs 75%)7

    Observed in trials
  5. Testes and hormone axis

    Anabolic steroids suppress own hormone production, sometimes for months9

    Observed in trials

Known targets1

Compound CHEMBL2106949: one described target, Binding, stronger than testosterone (muscle and prostate, rat and rabbit).

Androgen receptor
Gene
AR
UniProt
P10275
ChEMBL
CHEMBL1871
Action
Binding, stronger than testosterone (muscle and prostate, rat and rabbit)
Glossy blue 3D steroid molecules on light blue glassy muscle fibres, a transparent ring of spheres on the left
Methenolone binds to the androgen receptor. Symbolic image.

Use and 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
Glass vial with pale yellow oil and a black TPD label, next to it a disposable syringe with a blue needle cap on a white table
Symbolic image.

What the research shows

Methenolone has historical clinical use in anemia and muscle wasting. The general AAS pharmacology (Kicman 2008, Hartgens & Kuipers 2004) classes it as a mild, non-aromatizing DHT derivative.

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.

Response in older clinical studies35

Share of evaluable people, one group each without placebo

Remission in metastatic breast cancer3 8 of 41, lasting more than 3 months (1975)
All participants (no comparison group) 19.5%
Response in refractory anaemia5 7 of 19 (1979)
All participants (no comparison group) 36.8%

Percentages calculated from the numbers in the abstract. In breast cancer soft tissue metastases responded best, liver and brain metastases did not. In anaemia survival of responders was not visibly prolonged. The 1979 study does not state the form of methenolone.

Jaw bone after tooth extraction in rats7

Share with exposed bone, pretreatment with zoledronic acid

Exposed bone7 5 weeks after extraction
No medication (rat) 0%
Zoledronic acid alone (rat) 75%
Zoledronic acid plus methenolone enanthate (rat) 10%
Empty bone lacunae7 Share in the tissue section
No medication (rat) 1%
Zoledronic acid alone (rat) 8%
Zoledronic acid plus methenolone enanthate (rat) 3%

36 rats in three groups, six died during the experiment. An animal model of jaw necrosis after bone medication, not tested in humans.

Glass hourglass with white sand on a marble base, surrounded by glowing light arcs in a bright room
Most human data are decades old. Symbolic image.

Research status

Where the research stands

ClinicalTrials.gov lists no interventional trial for methenolone enanthate. As of 26 Oct 2026. 10

  1. Preclinical Jaw bone in rats
  2. Phase 1 no registered trial
  3. Phase 2 no registered trial
  4. Phase 3 no registered trial
  5. Approval not yet
No approval data: ChEMBL lists methenolone enanthate without a known phase. Older studies from the 1970s and 1980s used it in breast cancer.10

So far there is no registered trial in humans. 10

Side effects

  • Very mild: one of the lowest-side-effect anabolics.
  • Androgenic (DHT derivative) - hair loss possible in predisposed individuals.
  • HPTA suppression - even mild anabolics suppress, PCT topic.
  • No estrogen side effects.

Tolerability

Raised blood lipids in an older study

Out of 100 participants, how many developed raised blood lipids. One group of 28 women, no placebo.

43 of 100 All participants (no comparison group)
Event All participants (no comparison group)
Raised blood lipids overall4 43%
Type IIa (mainly cholesterol)4 36%
Type IIb (cholesterol and triglycerides)4 7%

Percentages calculated from 12, 10 and 2 of 28. One patient with type IIb had a heart attack during the study. The values did not depend on the amount and returned to normal in every case after stopping.4

Storage

Store the oil solution at room temperature, protected from light - no fridge needed. Out of reach of children.

Four glass vials with golden oil on a white shelf, next to them a folded light blue cloth
Oil solution at room temperature and protected from light, no fridge needed. Symbolic image.

Related

Related compounds

Same receptors or blends with Primobolan E (Methenolone Enanthate): all in the TPD lexicon.

Primobolan E (Methenolone Enanthate)
Primobolan Oral (Methenolone Acetate) The same compound taken orally Masteron E (Drostanolone Enanthate) Another DHT derivative with enanthate ester Masteron P (Drostanolone Propionate) Another DHT derivative, short ester Anavar (Oxandrolone) Oral DHT derivative Testosterone Enanthate Testosterone with the same ester Deca (Nandrolone Decanoate) Bound more strongly to the receptor in experiments

FAQ

Common questions about Primobolan E (Methenolone Enanthate)

Short answers, each backed by the sources below.

What is methenolone enanthate?

Methenolone is a steroid derived from DHT with a methyl group on the first carbon. The enanthate ester makes it oil-soluble and releases it slowly from the depot. In a comparison study methenolone bound to the androgen receptor in muscle and prostate more strongly than testosterone but less strongly than nandrolone.18

Is methenolone enanthate approved or studied?

ClinicalTrials.gov lists no interventional trial with methenolone enanthate (as of 26 October 2026) and ChEMBL gives neither a phase nor an approval year. It was studied in humans mainly in the 1970s and 1980s, for example in breast cancer. Everything here is the state of research, not a recommendation.10113

What do the older human studies show?

In 43 patients with metastatic breast cancer metastases regressed for more than 3 months in 8 of 41 evaluable patients, best in soft tissue. According to the authors it worked similarly to testosterone propionate but was less virilising. In a study of 19 people with refractory anaemia 7 responded to methenolone, survival was not visibly prolonged.35

What does GPR133 have to do with methenolone?

GPR133 is a receptor in the cell membrane. A 2025 paper found that DHT activates it in muscle cells, the messenger cAMP rises and muscle strength increases. Using cryo-electron microscopy the authors also showed methenolone bound to this receptor. This is basic research, consequences for use have not been studied.2

How long is methenolone detectable?

In a study from a doping laboratory one healthy volunteer took methenolone orally. The researchers found 16 metabolites, one of which was detectable in urine for up to 40 days. There are no such data for the injection with the long ester.6

Which side effects have been described?

In 28 women with breast cancer who additionally received methenolone enanthate blood lipids rose in 12, one had a heart attack. After stopping the values returned to normal in every case. Reviews of anabolic steroids also describe suppressed own hormone production, falling HDL cholesterol, rising blood pressure and acne.49

Are there animal studies?

Yes, for example on the jaw bone. Rats received a bone medication (zoledronic acid), then a tooth was extracted. Without methenolone enanthate bone was exposed afterwards in 75 percent, with it in 10 percent. The authors see potential for prevention, this has not been tested in humans.7

Glossary

Terms explained briefly

Dotted words in the text open these explanations directly.

Androgen receptor
Protein inside the cell that androgens bind to. Genes are then read, for example for muscle building.
Aromatisation
Conversion of certain androgens into oestrogen by the enzyme aromatase.
Blood lipids
Cholesterol and triglycerides in the blood. If they stay raised, the risk for the heart and vessels rises.
Depot
The oil solution stays in the tissue after the injection and releases the compound over days.
DHT
Dihydrotestosterone, a potent androgen. It is made from testosterone in the body and is not converted to oestrogen.
Enanthate ester
Long fatty acid chain on the compound. It makes it oil-soluble and releases it slowly from the depot.
GPR133
Receptor in the cell membrane (gene ADGRD1). DHT activated it in muscle cells.
Hormone axis (HPTA)
Hypothalamus, pituitary and testes together control the body's own testosterone production. Androgens from outside suppress this axis.
Remission
A tumour or disease measurably recedes for a certain time.

Practice

PCT / after coming off

Anabolic substances suppress the body's own testosterone production in the research context. Anyone who comes off a cycle (rather than running it continuously) typically uses a post-cycle therapy (PCT) to restart the natural axis (HPTA).

The standard scheme in the research/literature context combines a SERM (tamoxifen and/or clomifene, alternatively enclomiphene) over roughly four weeks, optionally preceded by HCG to re-sensitise the testes before the SERM block. An aromatase inhibitor (anastrozole/exemestane) belongs more to on-cycle estrogen control than to the PCT itself.

Tip: order the PCT items together with the cycle so they are already on hand when you come off.

This information serves research and educational purposes only. Not medical advice.

Tamoxifen (Nolvadex) SERM, core of PCT View Clomid (Clomifen) SERM, core of PCT View Enclomiphene (Androxal) SERM alternative View HCG testicular restart before PCT View Arimidex (Anastrozole) aromatase inhibitor, on-cycle View Aromasin (Exemestane) aromatase inhibitor, on-cycle View

Evidence

Sources

Show all 11 sourcesHide sources 9 Studies1 Trial registry1 Database checked 26 Oct 2026

Studies

  1. Binding of anabolic steroids to the androgen receptor in muscle and prostate

    Saartok et al., Endocrinology, 1984

    DOI 10.1210/endo-114-6-2100 PMID 6539197
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  2. GPR133 as a membrane androgen receptor, structure with methenolone

    Yang et al., Cell, 2025

    DOI 10.1016/j.cell.2025.01.006 PMID 39884271
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  3. Methenolone enanthate in metastatic breast cancer

    Notter, Acta Radiologica: Therapy, Physics, Biology, 1975

    DOI 10.3109/02841867509132696 PMID 1224996
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  4. Blood lipids on methenolone enanthate in breast cancer

    Garbrecht et al., Deutsche Medizinische Wochenschrift, 1981

    DOI 10.1055/s-2008-1070325 PMID 7215163
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  5. Methenolone in refractory anaemia

    Lockner, Acta Medica Scandinavica, 1979

    DOI 10.1111/j.0954-6820.1979.tb06010.x PMID 367090
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  6. New long-term urinary metabolite of methenolone

    He et al., Steroids, 2016

    DOI 10.1016/j.steroids.2015.10.015 PMID 26519767
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  7. Methenolone enanthate and jaw bone in rats

    Gürses et al., Journal of Oral Pathology and Medicine, 2024

    DOI 10.1111/jop.13574 PMID 39113433
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  8. Review of the pharmacology of anabolic steroids

    Kicman, British Journal of Pharmacology, 2008

    DOI 10.1038/bjp.2008.165 PMID 18500378
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  9. Review: effects and side effects of anabolic steroids in athletes

    Hartgens und Kuipers, Sports Medicine, 2004

    DOI 10.2165/00007256-200434080-00003 PMID 15248788
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed

Trial registry

  1. Search on ClinicalTrials.gov

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

    Checked 26 Oct 2026 via ClinicalTrials.gov API v2

Database

  1. Methenolone enanthate in ChEMBL

    ChEMBL, EMBL-EBI (CHEMBL2106949)

    Checked 26 Oct 2026 via ChEMBL

In the shop

Primobolan E (Methenolone Enanthate) in the catalog

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