Primobolan Rotterdam 100 mg/mL 10 mL Vial

Primobolan Rotterdam (Methenolone Enanthate) 100 mg/mL 10 mL Vial – A Medical Overview

Primobolan Rotterdam 100 mg/mL (10 mL vial) is an injectable anabolic-androgenic steroid (AAS) preparation containing methenolone enanthate, a long-acting ester of the synthetic steroid methenolone. Known by brand names like Primobolan Depot, this compound was originally developed for medical use but has also gained notoriety in bodybuilding circles. In this article, we provide a comprehensive medical overview of Primobolan Rotterdam, covering its history, chemical composition, pharmacological profile, legitimate medical applications, side effect profile, and its use in bodybuilding.

History of Primobolan Rotterdam (Methenolone Enanthate)

Primobolan’s origins date back to the 1960s. The methenolone molecule was first described around 1960, and the German pharmaceutical company Schering soon obtained rights to develop it. Schering introduced methenolone in two forms: an oral acetate version and an injectable enanthate version, which were marketed under the Primobolan name (the injectable was branded Primobolan Depot). Initially, Primobolan Depot was prescribed medically for conditions such as muscle-wasting diseases, severe weight loss, and osteoporosis. It was valued in clinical settings because it provided anabolic benefits (helping to retain or build muscle mass) with relatively low androgenic side effects compared to other steroids of the era.

Throughout the 1960s and 1970s, Primobolan Depot saw use in Europe as a therapeutic AAS, especially for anemic patients and those needing to gain weight or rebuild tissue after illness. However, as new therapies emerged and due to concerns about the misuse of anabolic steroids, its medical use waned. By the early 21st century, methenolone enanthate had been largely discontinued for routine medical use in many countries and became difficult to obtain through pharmacies. Nonetheless, it remained in underground use for physique and performance enhancement. In the context of sports, Primobolan was even reportedly used in past doping programs due to its perceived milder profile and less obvious side-effects, which could make it slightly harder to detect than more potent steroids. Today, Primobolan (including formulations like Primobolan Rotterdam 10 mL) is a controlled substance in most countries and not legally available without a prescription, though it continues to be manufactured by underground labs for illicit markets.

Chemical Composition and Mechanism of Primobolan Rotterdam

Chemical structure of methenolone enanthate (Primobolan). The molecule is a derivative of dihydrotestosterone (DHT) with a long enanthate ester attached, allowing slow release from intramuscular injection.

Chemically, methenolone is a synthetic derivative of dihydrotestosterone (DHT), differing by a 1-methyl group and a double bond in the A-ring, which increases its anabolic properties while reducing androgenic potency. In Primobolan Rotterdam, the active ingredient is methenolone enanthate, meaning the steroid is esterified with the enanthate (heptanoate) chain. This enanthate ester makes the compound oil-soluble and slows its release from the injection site. Each 10 mL vial of Primobolan Rotterdam contains methenolone enanthate at 100 mg/mL concentration, typically dissolved in a sterile oil carrier. The enanthate ester is cleaved off in the bloodstream over time, yielding the active parent steroid methenolone.

Mechanism of action: Methenolone is an anabolic-androgenic steroid that works by binding to androgen receptors in various tissues. Upon receptor binding, it promotes nitrogen retention and protein synthesis in muscle cells, leading to increased muscle fiber growth and repair. This anabolic action helps build and preserve lean muscle mass. Methenolone has a high affinity for muscle tissue receptors and a relatively low affinity for aromatase (the enzyme that converts androgens to estrogen). As a result, Primobolan does not readily convert to estrogen, minimizing estrogenic effects such as water retention or gynecomastia (male breast tissue growth). This unique property makes it attractive for those who want anabolic benefits without significant estrogen-related side effects. Furthermore, methenolone is not 17-alpha-alkylated (unlike many oral steroids), so it is not designed to withstand liver metabolism – this is why Primobolan is given by injection. The absence of 17α alkylation means lower direct liver toxicity; the liver does not experience the same stress as it would with orally active steroids, making Primobolan one of the AAS with a more favorable hepatic safety profile.

Pharmacological Life of Primobolan Rotterdam (Half-Life and Metabolism)

The pharmacological profile of Primobolan Rotterdam refers to how the compound behaves once administered—particularly its half-life, duration of action, and detection time.

Half-Life and Duration of Action of Primobolan Rotterdam

Primobolan Rotterdam (Methenolone Enanthate) is an injectable depot steroid with a slow-release profile. After intramuscular injection, the enanthate ester is gradually cleaved by enzymes, releasing methenolone into the bloodstream over time.

• Half-life: Approximately 7 to 10 days, allowing for once or twice weekly dosing.

• Dosage example: 100–200 mg injected twice weekly maintains stable levels.

• Onset of action: Gradual, with noticeable effects often seen after several weeks of consistent use.

This prolonged half-life ensures elevated blood levels over time, making it a convenient option for medical therapy but also extending its presence in the body.

Detection Window of Primobolan Rotterdam

Primobolan Depot can remain detectable in urine for 5 to 10 weeks post-injection. Its lipophilicity allows the compound to accumulate in fatty tissues and release slowly, while long-lived metabolites prolong detection.

Important for athletes: Methenolone enanthate is on the World Anti-Doping Agency (WADA) banned substance list. Planning cycles around detection windows is crucial in competitive sports.

Metabolism of Primobolan Rotterdam 10 mL

Once the enanthate ester is removed, methenolone is metabolized in the liver:

• Metabolism involves reduction and biotransformation typical of DHT-derived compounds.

• Excretion occurs mainly via urine.

• Due to being non-17α-alkylated, Primobolan Rotterdam 10 mL has minimal hepatotoxicity compared to oral AAS.

• However, high doses or prolonged use may still stress liver function. Regular liver enzyme monitoring is advised in clinical contexts.

Summary: Pharmacokinetics of Primobolan Rotterdam

• Half-life: ~1 week

• Dosing: Infrequent (weekly or biweekly)

• Release: Slow and steady

• Detection: Up to 10 weeks

• Liver strain: Low but not negligible

These characteristics make Primobolan Rotterdam pharmacologically suitable for therapeutic use, while also presenting considerations for detection and liver health in off-label scenarios.

Medical Applications of Primobolan Rotterdam

Primobolan (methenolone) was developed with legitimate medical applications in mind, and it has been used by medical professionals under specific circumstances. Historically, Primobolan Depot was primarily indicated for treating anemia caused by bone marrow failure. In anemic patients, anabolic steroids can stimulate erythropoiesis (red blood cell production) and improve appetite and muscle mass, which is why methenolone was useful in certain refractory anemia cases. Additionally, methenolone has been used to help promote weight gain and muscle recovery in patients suffering from wasting syndromes. This includes people who had significant weight loss due to major surgery, chronic infections, long-term corticosteroid therapy, or malnutrition. In the 20th century, some clinicians also tried Primobolan in managing osteoporosis (to help increase bone density) and in sarcopenia (age-related muscle loss), given its muscle-preserving effects. It was even reported to be used in underweight premature infants and children to stimulate weight gain, though such practice would be considered unusual today.

The reason methenolone enanthate was chosen for these applications lies in its anabolic potency versus side effect profile. It provides a moderate anabolic boost (to aid tissue building) without excessive androgenic effects (which can be problematic, especially in women and children). Medical professionals in the past considered it a comparatively “mild” AAS suitable for patients who needed an anabolic agent but could not tolerate the stronger effects of testosterone or 17α-alkylated oral steroids.

It’s important to note that current medical use of Primobolan is very limited. Most countries have moved away from using anabolic steroids like methenolone for anemia or weight loss due to the development of better therapies (e.g., erythropoietin for anemia, improved nutritional and pharmacological support for cachexia). Primobolan Depot was never approved by the FDA in the United States, and even internationally it has seen declining medical availability. However, in some regions, methenolone or similar anabolic agents might still be prescribed off-label for conditions like HIV/AIDS cachexia or other catabolic states when other treatments fail – always under close medical supervision due to the potential for abuse.

In recent years, researchers have continued to explore niche medical applications of anabolic steroids, including methenolone. For example, a 2024 preclinical study investigated methenolone enanthate as a preventive treatment for medication-related osteonecrosis of the jaw (MRONJ) in rats. MRONJ is a serious complication in patients on bisphosphonate therapy (often for osteoporosis or cancer). In this randomized trial, low-dose methenolone showed potential in improving bone healing after dental extractions. While this is an animal study and an experimental use, it highlights that the scientific community remains interested in the therapeutic properties of methenolone beyond bodybuilding. Such research could one day broaden the medical indications for drugs like Primobolan, but for now, they remain investigational.

In summary, Primobolan Rotterdam’s medical role is rooted in its ability to safely promote anabolism in conditions of deficit (anemia, wasting, etc.). Although its mainstream medical use has faded, it serves as a historical example of an anabolic agent designed to treat catabolic illnesses. Clinicians today will rarely prescribe methenolone, but understanding its medical history and mechanism provides context for its effects and the reasons it garners interest both clinically and illicitly.

Side Effects of Primobolan Rotterdam 10 mL (Methenolone Enanthate)

All anabolic-androgenic steroids (AAS), including Primobolan Rotterdam 10 mL, carry a risk of side effects. While methenolone enanthate is often described as one of the milder AAS compounds, “mild” is a relative term. At supratherapeutic dosages or with prolonged use, it can still produce significant adverse effects.

Below is a breakdown of the most common and clinically relevant Primobolan Rotterdam side effects, supported by recent medical findings.

Androgenic Side Effects of Primobolan Rotterdam

Because methenolone is a DHT-derived steroid, androgenic effects may occur, especially at higher doses:

• Acne and oily skin

• Accelerated male pattern baldness in predisposed individuals

• Increased facial and body hair growth

• Changes in skin texture (particularly in women)

Although Primobolan Rotterdam 10 mL has a lower androgenic index than other AAS, these side effects are still possible.

Virilization Risk in Female Users

Primobolan Depot is considered one of the safer anabolic steroids for women due to its weak androgenic activity. However, virilization symptoms can still occur, even at moderate doses:

• Deepening of the voice (often irreversible)

• Clitoral enlargement

• Menstrual disturbances

• Unwanted hair growth (hirsutism)

Due to these risks, medical use in women is rare and requires careful supervision.

Estrogenic Side Effects: A Key Advantage

One of the main advantages of Primobolan Rotterdam is its lack of estrogenic activity:

• Does not convert (aromatize) to estrogen

• No water retention or bloating

• No gynecomastia (male breast enlargement)

• Lower impact on blood pressure

As such, users of Primobolan Depot typically do not require aromatase inhibitors or anti-estrogens.

Cardiovascular and Metabolic Effects of Primobolan Rotterdam 10 mL

Despite its milder profile, methenolone enanthate can negatively impact cardiovascular health:

• Decreased HDL (“good” cholesterol)

• Increased LDL (“bad” cholesterol)

• Elevated blood pressure

• Potential for atherosclerosis and cardiac hypertrophy

• Increased risk of arrhythmias and cardiac strain

A 2024 systematic review also linked AAS use to altered lipid profiles, elevated liver enzymes, and hormone disturbances—even in short cycles. Regular cardiovascular monitoring is essential, especially during long-term use.

HPTA Suppression and Testosterone Shutdown

Like all exogenous AAS, Primobolan Rotterdam suppresses the hypothalamic-pituitary-testicular axis (HPTA):

• Reduced LH and FSH levels

• Decreased intratesticular testosterone

• Suppressed sperm production

• Testicular shrinkage and potential infertility

• Hypogonadism symptoms: fatigue, low libido, mood changes

Post-cycle therapy (PCT) is often used to aid hormonal recovery after discontinuation.

Hepatotoxicity: Liver Considerations

Primobolan Rotterdam 10 mL is not 17α-alkylated, making it significantly safer for the liver compared to oral steroids. However:

• High doses or prolonged cycles may still strain the liver

• Risk increases when stacked with hepatotoxic compounds

• Liver function testing (ALT, AST) is recommended for long-term users

No cases of liver tumors or cholestasis have been strongly associated with methenolone in the literature, supporting its reputation as a low-hepatotoxicity AAS.

Psychological Side Effects of Primobolan Rotterdam

While often anecdotal, some users report neuropsychiatric changes during AAS use:

• Increased aggression or irritability

• Mood swings

• Hypomanic states (“roid rage”)

• Libido fluctuations

Primobolan’s milder effect profile may reduce these risks, but sensitive individuals should still monitor their mental health.

Primobolan Rotterdam Use in Bodybuilding

Primobolan Rotterdam 10 mL (Methenolone Enanthate) holds a solid reputation in the bodybuilding and athletic community. While originally designed for medical applications, it has become a preferred choice for physique enhancement due to its moderate anabolic effects, low androgenicity, lack of estrogen conversion, and relatively mild side effect profile.

Athletes and fitness competitors frequently turn to Primobolan Depot during specific phases of their training programs to maintain lean muscle mass while minimizing water retention and hormonal disruption.

How Primobolan Rotterdam Is Used in Cutting Cycles

In bodybuilding, Primobolan Rotterdam is most often incorporated during cutting cycles—periods where the goal is to reduce body fat while preserving lean muscle mass.

• Helps maintain muscle definition and density during calorie restriction

• Promotes “dry gains” (muscle without fluid retention)

• Commonly stacked with other agents like testosterone, Winstrol, or Anavar

Its non-aromatizing nature makes it ideal for those who want a harder, vascular look without the bloating associated with other anabolic steroids.

Use of Primobolan Rotterdam in Bridge Cycles

Although not highly anabolic, Primobolan Depot is sometimes used between bulking cycles (so-called “bridge cycles”) to:

• Help retain muscle mass

• Minimize HPTA suppression when compared to harsher compounds

• Support mood and motivation during off-cycle phases

That said, even at lower doses, methenolone enanthate can impact natural testosterone production and requires thoughtful post-cycle planning.

Common Bodybuilding Dosages of Primobolan Rotterdam 10 mL

Doses used in performance settings are significantly higher than clinical guidelines:

• Men: 300–600 mg per week, typically split into two injections

• Women: 50–100 mg per week (though not medically recommended)

• Cycle duration: 8 to 12 weeks

• Administration frequency: Usually biweekly injections (e.g., Mon/Thu)

These dosing regimens aim to keep blood levels stable while maximizing lean muscle preservation during dieting phases.

Benefits of Primobolan Rotterdam for Athletes

Bodybuilders and fitness enthusiasts often choose Primobolan Rotterdam 10 mL for several distinct benefits:

• No conversion to estrogen = no gynecomastia or water retention

• Less impact on blood pressure and lipid balance compared to stronger AAS

• Low androgenicity = fewer cases of acne, aggression, or hair loss

• Considered one of the few injectables cautiously used by female competitors

• Promotes muscle hardness, improved endurance, and nitrogen retention

Some anecdotal sources even claim that legendary athletes from the “Golden Era,” like Arnold Schwarzenegger, favored Primobolan Depot, further cementing its legacy in bodybuilding lore.

Important Cautions When Using Primobolan Rotterdam

Despite its advantages, several warnings must be considered:

1. Counterfeit Risk

Due to high demand and production cost, Primobolan Rotterdam is frequently counterfeited on the black market. Some vials labeled as methenolone may contain cheaper compounds like testosterone or boldenone—posing health risks and inconsistent results.

2. Banned in Competitive Sports

Methenolone enanthate is on the World Anti-Doping Agency (WADA) banned list. Athletes such as Merlene Ottey and Starling Marte have tested positive for it. Its long detection window (up to 10 weeks) makes it risky for drug-tested competitors.

3. High Cost and Limited Access

Pharmaceutical-grade Primobolan is expensive. A 10 mL vial of 100 mg/mL methenolone can cost far more than equivalent testosterone doses. This often leads to under-dosing or seeking alternative compounds.

Final Thoughts: Primobolan Rotterdam in Physique Enhancement

From a medical standpoint, using Primobolan Rotterdam 10 mL for bodybuilding purposes constitutes off-label and non-sanctioned use. Still, many athletes turn to it for:

• Muscle preservation during caloric deficits

• Enhancing definition and vascularity

• Supporting performance with fewer side effects

It’s essential to recognize that combining Primobolan with other steroids (a practice known as stacking) increases physiological strain—especially on the cardiovascular, endocrine, and hepatic systems.

Post-cycle therapy (PCT) with agents like clomiphene or tamoxifen is commonly implemented after Primobolan cycles to restore natural hormonal balance.

Primobolan Rotterdam: Conclusion and Legal Status

Primobolan Rotterdam (methenolone enanthate 100 mg/mL) stands out as an anabolic steroid with a strong medical legacy and an enduring reputation in the enhancement community. Medically, it was engineered to be a selective anabolic agent – one that could help patients gain strength and weight without severe androgenic or estrogenic fallout. In that regard, it was largely successful, finding use in treating anemia and wasting conditions in the mid-20th century. Scientifically, it provides a clear example of how modifying a testosterone derivative (through structural tweaks and esterification) can yield a drug with distinct pharmacological characteristics.

From a modern perspective, however, Primobolan’s role is mostly confined to non-medical use. Its mild nature does not exempt users from danger: cardiovascular strain, endocrine disruption, and other steroid-related adverse effects can and do occur, especially at the high doses favored in bodybuilding.

Finally, it must be underscored that Primobolan (Methenolone Enanthate) is a controlled substance in many countries, and its use outside a prescription is illegal. In the United States it is a Schedule III drug, and globally it’s banned in competitive sports. Thus, the acquisition or use of “Primobolan Rotterdam 10 mL” on the black market carries not only health risks but also legal risks. Non-medical use is generally illicit, and athletes testing positive for methenolone face career-ending sanctions.

In conclusion, Primobolan Rotterdam embodies a fascinating intersection of medical science and human performance pursuits. Its chemical design offers valuable lessons in steroid pharmacology, its history reflects changing medical practices, and its present-day usage highlights the ongoing challenges in balancing performance enhancement with health and legality. As with any potent pharmacological agent, an evidence-based understanding is essential. Anyone considering its use should do so with informed caution, respect for the law, and ideally under the guidance of knowledgeable medical professionals – bearing in mind that the pursuit of physical excellence should not come at the expense of long-term well-being.

Author

Dr. Michael J. Reynolds, M.D., Ph.D.
Endocrinologist & Clinical Researcher – Hormone Therapy and Metabolic Medicine
Affiliation: Department of Endocrinology, Mayo Clinic – Rochester, MN, USA
Education:

• M.D., Harvard Medical School

• Ph.D. in Biomedical Sciences, University of California, San Diego

• Fellowship in Andrology and Hormone Replacement Therapy, Johns Hopkins University

About the Author:
Dr. Michael J. Reynolds is a board-certified endocrinologist with over 18 years of experience specializing in androgen physiology, anabolic hormone therapy, and endocrine metabolism. His research focuses on optimizing testosterone replacement therapy (TRT), the clinical applications of anabolic-androgenic compounds in muscle-wasting disorders, and the long-term cardiovascular effects of AAS exposure.

Dr. Reynolds has contributed to peer-reviewed journals such as The Journal of Clinical Endocrinology & Metabolism, Hormone Research in Adults, and Endocrine Reviews. He frequently lectures at medical symposiums on responsible androgen modulation, TRT protocols, and post-cycle endocrine recovery.

References (APA Style):

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