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Muscle & performance

Masteron P (Drostanolone Propionate)

The cutting hardening steroid - DHT derivative with an anti-estrogenic note, short ester.

1 min read 10 sources

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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 short side chain in a bright lab, symbolic image for Drostanolone Propionate
Formerly approved · in the USA, discontinued

Summary

At a glance

Sources checked on 26 Oct 2026

Remission in breast cancer
46 %

91 patients, three androgens equally effective, after 16 weeks, chemotherapy added from week 41

Less growth of breast cancer cells
94 %

Cell culture, highest concentration tested (lowest 16%)2

Detectable in urine
24 days

Breakdown products after one intramuscular injection, one volunteer, doping research3

Trials in the registry
0 trials

no trial with drostanolone on ClinicalTrials.gov, as of 25 Oct 20269

  • Drostanolone is 2-alpha-methyl-dihydrotestosterone, a DHT derivative. As the propionate it carries a short ester, the compound itself acts on the androgen receptor.48
  • In the USA Drostanolone Propionate was approved as an injection, according to the FDA database the product is no longer marketed. It used to be given in advanced breast cancer.7
  • In a controlled trial from 1978 with 91 patients three androgens worked equally well: on average tumours regressed in 24 percent after 4 weeks and in 46 percent after 16 weeks with added chemotherapy.1
  • In breast cancer cells in the lab it inhibited growth by 16 to 94 percent depending on concentration. After one injection breakdown products were detectable in urine for up to 24 days.23
  • There are no new trials. On side effects there are only reviews of the whole drug class. Everything here is the state of research, not a recommendation.965
Profile

Updated June 2026

How long does it stay in the body?

Share left after one dose, calculated with a half-life of ~1.5 days

Half-life ~1.5 days
After 3 days: 25 %
Day 1.5 · 50 %Day 2, next dose · 40 %Day 3 · 25 %Day 4.5 · 12.5 %Day 7.5 · 3.1 %

Simplified model without an absorption phase, half-life from the TPD lexicon. The lexicon gives 1 to 2 days, we calculate with the middle.

Class
DHT derivative

short propionate ester

Use
Intramuscular

every other day

Half-life
about 1-2 days
WADA
banned

anabolic

Sizes
100mg/ml

1 size in the shop

Contents 13 sections
  1. At a glance
  2. What is Masteron P?
  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 Masteron P?

Masteron P (Drostanolone Propionate) is a DHT derivative with a short propionate ester. It is not primarily a mass-building steroid but popular for "hardening" in the cutting phase - it gives muscle a dry, defined look at low body fat. Historically drostanolone was even used for breast cancer because it acts anti-estrogenically.

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

Comparison

Drostanolone and relatives

The same compound with another ester and related DHT derivatives, as described in the TPD lexicon. Tap a card to open its entry.

Drostanolone, short ester Masteron P (Drostanolone Propionate) AR
Drostanolone, long ester Masteron E (Drostanolone Enanthate) AR Oral 1-alpha-methyl-DHT Proviron (Mesterolone) AR Testosterone, same ester Testosterone Propionate AR

How it works

As a DHT derivative masteron does not aromatize and even has a weakly anti-estrogenic effect (it competes at aromatase). That contributes to the "dry" look. The effect is mainly visible at already low body fat - at high body fat it does little visually.

Where it acts

Where drostanolone acts

Tap a point or a card. Red = androgen receptor, grey = observed or from reviews of the drug class.

  1. Skeletal muscle

    Agonist at the androgen receptor, direct binding8

    AR
  2. Pituitary

    Anabolic steroids suppress natural hormone production according to a review, sometimes for months6

    Observed in trials
  3. Blood lipids

    Anabolic steroids lower HDL cholesterol according to a review6

    Observed in trials
  4. Skin

    Acne is among the most often self-reported effects according to a review6

    Observed in trials
  5. Kidney and urine

    Breakdown products detectable in urine for up to 24 days3

    Observed in trials

Targets in the ChEMBL database8

Compound CHEMBL1201048: one recorded mechanism, agonist with direct binding to the human receptor.

Androgen receptor
Gene
AR
UniProt
P10275
ChEMBL
CHEMBL1871
Action
Agonist, direct binding
Glossy blue 3D steroid molecules gather around a transparent ring-shaped structure at the end of light blue fibre bundles
Drostanolone binds to the androgen receptor as an agonist. 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 on a white surface
Symbolic image.

What the research shows

Drostanolone has historical clinical use as an anti-estrogenic agent in breast cancer. The general AAS pharmacology (Kicman 2008, Hartgens & Kuipers 2004) describes the DHT-derivative properties.

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.

Regression in advanced breast cancer1

Share of the 91 patients with remission, average of three equally effective androgens

After 4 weeks1 androgen only
Three androgens on average (one of them drostanolone) 24%
After 16 weeks1 with cyclophosphamide from week 4
Three androgens on average (one of them drostanolone) 46%

Testolactone, drostanolone and nandrolone were compared, with no difference in effect. Values for the single drugs are not in the abstract. Historical treatment, no longer standard today.

Growth inhibition of breast cancer cells2

Inhibition in percent, MCF-7 cell line, two days of exposure

Drostanolone propionate2
Lowest concentration tested 16%
Highest concentration tested 94%

The range spans three orders of magnitude in concentration. Combined with the chemotherapy drug 5-fluorouracil the effects added up. Lab experiment, not tested in humans.

Glass fibre bundle with hexagonal crystal ends, surrounded by bright arcs of light
The clinical data are old and come from cancer treatment. Symbolic image.

Research status

Where the research stands

Drostanolone Propionate predates today's trial registries, the clinical papers date from the 1960s and 1970s. As of 25 Oct 2026. 9

  1. Preclinical Breast cancer cells in the lab
  2. Phase 1 no registered trial
  3. Phase 2 no registered trial
  4. Phase 3 no registered trial
  5. Approval in the USA, discontinued
Formerly approved in the USA as an injection, according to the FDA database discontinued. ChEMBL lists Drostanolone Propionate with phase 4 as the highest phase.7

The approval predates today's trial registries, so the register shows no current trial for this form. 9

Side effects

  • Androgenic: as a DHT derivative - hair loss in predisposed individuals, acne.
  • Lipids: can lower HDL.
  • HPTA suppression: PCT topic.
  • Barely any estrogen side effects, since no aromatization.

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.
Level · Masteron P (Drostanolone Propionate)

How the level builds up

One dose every other day: each dose adds to what is left of the previous one.

Lexicon: Intramuscular, every other day
Peak 1.66×Trough 0.66×
Day 6 · 4. dose
1.62× of the first dose
Plateau
from Day 6

98 % of the plateau after dose 4

Peak
1.66×

of the first dose

Trough
0.66×

before the next dose

Simplified model, values relative to the first dose, no dosing information. Dashed: the first dose alone, green: the plateau.

Related

Related compounds

Same receptors or blends with Masteron P (Drostanolone Propionate): all in the TPD lexicon.

Masteron P (Drostanolone Propionate)
Masteron E (Drostanolone Enanthate) Same compound, long ester RIPEX 225 Contains Drostanolone Propionate plus testosterone propionate and trenbolone acetate Tren/Test/Mast Short 150 Contains Drostanolone Propionate among three short esters Blend 300 (TMT 100/100/100) Contains drostanolone plus trenbolone and testosterone Proviron (Mesterolone) Related methyl-DHT, oral Testosterone Propionate Testosterone with the same ester

FAQ

Common questions about Masteron P (Drostanolone Propionate)

Short answers, each backed by the sources below.

Is Drostanolone Propionate approved?

No longer marketed. In the USA it was approved as an injection, the FDA database lists the product as discontinued. ChEMBL gives phase 4 as the highest phase. ClinicalTrials.gov lists no trial (as of 25 October 2026).789

What is drostanolone chemically?

2-alpha-methyl-dihydrotestosterone, i.e. DHT with a methyl group on carbon atom 2. In the body it is mainly broken down to 2-alpha-methyl-androsterone and excreted bound to glucuronic acid. As the propionate it carries a short ester, as the enanthate a long one.410

What was it used for in the past?

In advanced breast cancer. In a controlled trial from 1978 with 91 patients testolactone, drostanolone and nandrolone worked equally well: on average tumours regressed in 24 percent after 4 weeks and in 46 percent after another 12 weeks with cyclophosphamide. In breast cancer cells in the lab Drostanolone Propionate inhibited growth by 16 to 94 percent depending on concentration.12

How long is drostanolone detectable?

In a doping research study one volunteer received an intramuscular injection. Two new breakdown products were detectable in urine for up to 24 days, with a simpler method for up to 7 days. Eleven breakdown products were found in total.3

Which side effects have been described?

There are no studies with frequencies for drostanolone. Reviews of anabolic steroids list increased sexual drive, acne, more body hair and more aggression as the most often self-reported effects. HDL cholesterol also falls, blood pressure can rise and natural hormone production can stay disturbed for months after stopping.65

What is the difference between propionate and enanthate?

The compound is the same, only the attached acid chain differs: propionate is short, enanthate long. A long ester is released more slowly from the oil depot. There are no measured human half-lives for the two drostanolone esters.10

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.
Aromatase
Enzyme that converts certain androgens into estrogen.
Cutting
Diet phase aiming to lose fat while keeping muscle.
DHT
Dihydrotestosterone, a strong androgen made from testosterone in the body. It cannot be converted to estrogen.
Ester
Attached acid chain. It sets how fast the compound leaves the oil depot. It is split off in the body.
HDL cholesterol
Cholesterol carrier that takes fat from the vessels to the liver. Low levels are considered unfavourable for the heart and vessels.
Hormone axis (HPTA)
Hypothalamus, pituitary and testes together control the body's own testosterone production. Anabolic steroids from outside suppress this axis.
PCT
Post cycle therapy, the phase after stopping in which natural hormone production is meant to restart.
Propionate ester
Short acid chain on the compound. It makes it oil-soluble but is released faster than long esters.
Remission
Regression of a disease, in cancer a shrinking or disappearance of tumours.

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 10 sourcesHide sources 6 Studies1 Trial registry3 Database checked 26 Oct 2026

Studies

  1. Controlled trial: three androgens in advanced breast cancer

    Wolff und Rieche, Onkologie, 1978

    DOI 10.1159/000213943 PMID 362297
    Checked 26 Oct 2026 via doi.org, Crossref (Online-Jahr 2009), PubMed
  2. MCF-7 breast cancer cells with drostanolone propionate and 5-fluorouracil

    Fujita et al., European Journal of Cancer and Clinical Oncology, 1983

    DOI 10.1016/0277-5379(83)90200-6 PMID 6688585
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  3. Breakdown products of drostanolone in urine

    Liu et al., Steroids, 2016

    DOI 10.1016/j.steroids.2016.01.013 PMID 26826321
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  4. Structure and breakdown of mesterolone and drostanolone

    de Boer et al., Journal of Steroid Biochemistry and Molecular Biology, 1992

    DOI 10.1016/0960-0760(92)90146-a PMID 1606052
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  5. 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
  6. 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. US approval (NDA 012936), discontinued

    Drugs@FDA, U.S. Food and Drug Administration

    Checked 26 Oct 2026 via openFDA-API
  2. Mechanism in ChEMBL

    ChEMBL, EMBL-EBI (CHEMBL1201048)

    Checked 26 Oct 2026 via ChEMBL
  3. Structure of Drostanolone Propionate in PubChem

    PubChem, U.S. National Library of Medicine (CID 224004)

    Checked 26 Oct 2026 via PubChem

In the shop

Masteron P (Drostanolone Propionate) in the catalog

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