Masteron P | PED Test New Zealand

Executive Summary & Compound Identity

Drostanolone propionate (Masteron P) represents a fascinating clinical dichotomy: originally developed in 1959 and FDA-approved in 1961 as a breakthrough oncological agent for estrogen-receptor-positive (ER+) recurrent breast cancer, it has evolved into an obsolete clinical drug but a ubiquitous illicit performance-enhancing steroid in body-building and athletics. This interactive dashboard allows researchers, clinicians, toxicologists, and legal analysts to systematically explore its molecular modifications, metabolic stability, systemic toxicities, WADA detection profiles, and legal status under New Zealand law.

Biological Target

Androgen Receptor

Full Agonist (NR3C4)

Estrogenic Conversion

0% (Zero)

Impervious to Aromatase

Elimination Half-Life

2.5 Days

Short C17β Propionate Ester

Clinical Status

Discontinued / Lapsed

Replaced by SERMs & AIs

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Clinical Heritage (1960s – 1980s)

• Target Indication: Palliation of ER+ recurrent postmenopausal mammary carcinoma.
• Key Efficacy: Yielded a 44% objective tumor regression rate in clinical trials, doubling surgical oophorectomy (22%).
• Obsoletion: Obsoleted by non-virilizing alternatives like Tamoxifen (SERM) and Letrozole/Anastrozole (Aromatase Inhibitors).

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Contemporary Clandestine Misuse

• Primary Demographic: Bodybuilders and strength athletes during pre-contest "cutting" phases.
• Efficacy Drivers: Preserves muscle protein synthesis under severe caloric deficits while acting as a cosmetic "drying agent" via anti-estrogenic receptor competition.
• Severe Hazards: Induces pathological left ventricular hypertrophy (LVH), severe HDL cholesterol crashes, and irreversible HPGA suppression.

Chemical Architecture & Molecular Modifications

Drostanolone is a synthetic derivative of 5α-dihydrotestosterone (DHT). Two specific synthetic modifications fundamentally alter its biological fate compared to parent DHT: a 2α-methyl substitution on the A-ring, and a 17β-propionate ester modification on the D-ring.

Physicochemical Profile

Parameter	Value / Specification	Biological / Pharmacological Significance
IUPAC Name	(2R,5S,8R,9S,10S,13S,14S,17S)-17-hydroxy-2,10,13-trimethyl-1,2,4,5,6,7,8,9,11,12,14,15,16,17-tetradecahydrocyclopenta[a]phenanthren-3-one propanoate	Formal systematic chemical nomenclature.
Molecular Formula	C23H36O3	Esterified parent structure.
Monoisotopic Mass	360.266445 g/mol	Exact mass utilized in high-resolution LC-MS anti-doping screening.
CAS Numbers	521-12-0 (Ester) 58-19-5 (Base)	Unique chemical abstracts registry identifiers.
Partition Coefficient (LogP)	5.3	Extreme lipophilicity; enables sustained release from intramuscular oil vehicle.
Melting Point	114–120 °C	Physical crystalline property (up to 128 °C in pure samples).
Optical Rotation [α]	+24° (D line)	Specific stereochemical light-rotation index.

The Two Structural Masterkeys

🛡️ 1. The 2α-Methyl Substitution

Endogenous DHT is rapidly inactivated in skeletal muscle by 3α-hydroxysteroid dehydrogenase (3α-HSD) into weak 3α-androstanediol. The 2α-methyl addition creates a massive steric barrier around the 3-ketone, neutralizing 3α-HSD binding and granting potent, sustained skeletal muscle anabolism.

💉 2. The C17β Propionate Ester

Attaches a 3-carbon fatty acid chain via covalent ester bond at C17β. Increases lipophilicity (LogP 5.3), requiring deep intramuscular injection in oil depot, from which systemic esterases gradually hydrolyze free active drostanolone.

Microbiological Biotransformation Note: Whole-cell fungal biocatalysis (*Cephalosporium aphidicola*, *Fusarium lini*) hydroxylates the hydrocarbon core, producing cytotoxic metabolites like 2α-methyl-3α,14α,17β-trihydroxy-5α-androstane.

Pharmacodynamics & Receptor Mechanics

Drostanolone functions as a non-selective full agonist of the intracellular Androgen Receptor (NR3C4). Because it is already 5α-reduced, it bypasses 5α-reductase enzymatic amplification. Furthermore, its 5α-reduced, 2α-methylated steroid core physically precludes binding to the active site of the aromatase enzyme, guaranteeing 0% conversion to estrogen.

Intracellular Genomic Signaling Cascade

Step 1

Passive Diffusion

Free lipophilic drostanolone diffuses across the phospholipid bilayer into target cell cytoplasm.

Membrane Crossing

Step 2

AR LBD Binding

Binds with high affinity to Ligand-Binding Domain of AR-A or AR-B, prompting HSP90 dissociation.

HSP90 Dissociation

Step 3

Nuclear Translocation

Dimerized AR-drostanolone complex translocates through nuclear pores into cell nucleus.

Dimerization

Step 4

ARE Transcription

Binds Androgen Response Elements (AREs) to upregulate nitrogen retention & satellite cell proliferation.

Anabolism

Enzymatic & Receptor Profile Comparison

Comparing Drostanolone against Testosterone and SARMs

Direct Anti-Estrogenic & Receptor Dynamics

Competitive Estrogen Receptor (ER) Blockade:

Clinical studies demonstrate that drostanolone competes directly with estradiol for ER binding in target mammary tissues, physically antagonizing estrogenic signaling without undergoing conversion itself.

Receptor Downregulation:

Sustained AR activation by drostanolone downregulates estrogen and prolactin receptor expression levels in target breast tissue, halting cell cycle progression in ER+ carcinomas.

Contrast with SARMs (Selective AR Modulators):

Unlike tissue-selective SARMs (e.g. MK-2866, LGD-4033) which attempt to isolate muscle anabolism from prostatic androgenicity, drostanolone is a full, non-selective systemic androgen. (Note: SARMs metabolites like LGD-4033 M8 can paradoxically act as AR antagonists).

Pharmacokinetics & Ester Release Simulator

Because drostanolone is inactive orally due to complete first-pass hepatic degradation, it requires parenteral administration in an oily depot. The propionate ester (3 carbons) dictates a short elimination half-life (~2.5 days). Use the interactive simulator below to model systemic blood concentration curves across different ester derivatives and injection frequencies over a 30-day window.

Simulator Controls

Select Steroid Ester

Injection Frequency

Dose per Injection (mg)

Ester Clearance Insights:

Shorter esters (Propionate) require frequent injections (Q2D/Q3D) to prevent rapid blood troughs, whereas long esters (Enanthate) take 3-4 weeks to reach steady state.

30-Day Plasma Level Simulation

Peak: -- | Trough: --

Ester Hydrophobic & Duration Comparison

Ester Name	Position	Fatty Acid Moiety	Carbon Chain Length	Estimated Half-Life	Partitioning Profile
Drostanolone Propionate	C17β	Propanoic acid	3 Carbons	~2.5 Days	Rapid depot leaching; requires frequent dosing
Metenolone Acetate	C17β	Ethanoic acid	2 Carbons	~1.5 Days	Ultra-short duration
Drostanolone Enanthate	C17β	Heptanoic acid	7 Carbons	~5–7 Days	Sustained lipophilic depot; weekly dosing
Nandrolone Decanoate	C17β	Decanoic acid	10 Carbons	~7–12 Days	Very high lipophilicity; long release tail

Historical Oncology vs. Contemporary Doping

In the late 1960s, clinical trials conducted by groups like the Cooperative Breast Cancer Group proved that drostanolone propionate offered an effective non-surgical endocrine ablation alternative for advanced breast cancer. Today, that clinical application is extinct, replaced entirely by clandestine bodybuilding preparation protocols.

Historical Clinical Efficacy (1968–1972 Trials)

Objective Tumor Regression Rates in ER+ Postmenopausal Breast Cancer

Drostanolone (200 mg IM 2x/week) achieved a 44% regression rate, doubling bilateral surgical oophorectomy (22%). However, off-target virilization (hirsutism, voice deepening, clitoromegaly) led to its phase-out.

Contemporary Pre-Contest "Cutting Stack" Mechanics

Typical Illicit Dosing Paradigm 200–600 mg/week

Administered deep IM every 2 days (Q2D) due to short propionate half-life. Extreme users exceed 1,000 mg weekly.

Synergistic Stacking Partners

Frequently stacked with Testosterone Propionate (base androgen) and Trenbolone Acetate (19-nor derivative) during the final 8–12 weeks before contest.

Cosmetic Hardening & "Drying" Effect

Converts zero percent to estrogen while antagonizing peripheral estrogen receptors. This mitigates subcutaneous fluid retention (edema) caused by aromatizable stacked steroids, creating a dense, highly vascular physique required by judges.

Toxicological Sequelae & Multi-System Pathology

While non-17α-alkylated steroids like drostanolone spare the liver from acute sub-massive necrosis seen with oral steroids, chronic supra-physiological administration drives severe multi-system pathology. Select an organ system below to explore specific molecular toxicity mechanisms.

Target Organ Systems

Relative Toxicity Impact Profile

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Forensic Autopsy Case Study Highlight (34yo Athlete)

Post-mortem morphological examination of a 34-year-old bodybuilder who collapsed post-workout revealed drastic concentric Left Ventricular Hypertrophy (LVH) with replacement myocardial fibrosis and a severely narrowed right coronary artery lumen. Toxicological MS analysis confirmed high serum levels of drostanolone propionate stacked with stanozolol (56 µg/L), metandienone (8 µg/L), and clenbuterol (1 µg/L), culminating in fatal myocardial hypoxia.

Global Anti-Doping Detection & New Zealand Legal Framework

Under WADA's Prohibited List (Section S1 Anabolic Agents), drostanolone is banned at all times. WADA accredited laboratories utilize Liquid Chromatography-Ion Mobility-Mass Spectrometry (LC-IM-MS) to separate isobaric urine interferences by Collision Cross Section (CCS). Legally, New Zealand controls drostanolone as a Class C Controlled Drug and a Prescription Medicine.

LC-IM-MS Ion Mobility CCS Explorer

Adduct Mass-to-Charge (m/z) vs. Collision Cross Section (Å²)

Ion mobility separates ions in a gas drift tube by three-dimensional shape (CCS in Å²). Coupled with MS/MS, this guarantees unambiguous detection of intact phase II metabolites like 3α-hydroxy-2α-methyl-5α-androstan-17-one.

New Zealand Statutory Penalty Lookup

Select Offense Category

Medsafe Border Control & Regulatory Status:

Drostanolone propionate status is "Approval Lapsed / Unapproved" in NZ. Interceptions by NZ Customs Service result in immediate seizure under Section 26 of the Medicines Act 1981 alongside Misuse of Drugs Act smuggling prosecutions.

Trenbolone

Testosterone

Masterton

Primobolan

Clenbuterol

Cialis

Masteron P (Drostanolone Propionate)