Methenolone Acetate (Primobolan)
Active Substance: Methenolone Acetate
Description
Methenolone Acetate (Primobolan)
Methenolone Acetate, also known as Primobolan (oral form), Primobolan S, and Nibal, is a synthetic androgen and anabolic-androgenic steroid (AAS). It is a derivative of dihydrotestosterone (DHT) and is known for its relatively mild nature compared to other steroids. It was originally used medically to treat anemia due to bone marrow failure, though its use has largely been discontinued.
There is also an injectable version called Methenolone Enanthate (Primobolan Depot), which is the enanthate ester of methenolone.
Anabolic-Androgenic Ratio
Methenolone is known for having a favorable anabolic-to-androgenic ratio. While specific numbers can vary in different studies and are often based on animal models, it is generally considered to have a ratio of approximately 1:2 to 1:3. This means its anabolic (muscle-building) effects are stronger than its androgenic (masculinizing) effects.
Side Effects and Benefits
Benefits:
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Muscle Growth: It promotes lean muscle mass gains.
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Fat Reduction: It can help with fat loss.
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Mild Nature: It is considered one of the milder anabolic steroids, particularly with regard to liver toxicity for the oral form and a lower risk of certain side effects compared to more potent steroids.
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No Estrogenic Effects: As a DHT derivative, it does not aromatize into estrogen, meaning it does not cause estrogenic side effects like gynecomastia (male breast tissue development) or significant water retention.
Side Effects:
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Androgenic Side Effects: Despite its mild androgenic ratio, it can still cause androgenic side effects, especially in genetically predisposed individuals. These include acne, increased body and facial hair growth, and accelerated male pattern baldness.
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Cardiovascular Issues: It can negatively impact cholesterol levels, potentially increasing LDL ("bad") cholesterol and decreasing HDL ("good") cholesterol, which can increase the risk of cardiovascular disease.
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Testosterone Suppression: Like most anabolic steroids, it suppresses the body's natural testosterone production, which can lead to a range of issues including reduced libido, fatigue, and even depression. Post-cycle therapy (PCT) is often necessary to help restore natural hormone levels.
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Liver Toxicity: While considered less hepatotoxic than many other oral steroids, prolonged use or high doses can still lead to liver damage.
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Virilization in Women: In women, Methenolone Acetate can cause virilization, which includes the development of masculine traits such as a deepened voice, increased body hair, and clitoral enlargement.
Pros and Cons
Pros:
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Low Androgenic Activity: The mild androgenic nature is a pro for many users, as it reduces the risk of side effects like hair loss and acne.
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No Aromatization: The lack of estrogenic effects makes it a good choice for those who want to avoid water retention and gynecomastia.
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Promotes Lean Gains: It is favored for its ability to produce high-quality, lean muscle gains without the "bloated" look often associated with other steroids.
Cons:
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Lower Potency: Its mild nature means it's not as potent for mass building as other, more powerful steroids.
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Testosterone Suppression: It still suppresses natural testosterone production, requiring a proper post-cycle therapy.
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Cost and Availability: Due to its discontinued medical use in many places, it is often more expensive and harder to find on the illicit market, and its quality can be questionable.
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Potential Side Effects: While milder, the risk of androgenic and cardiovascular side effects, as well as liver stress, is still present.
Dosage and Frequency
There is no officially recommended dosage for non-medical use. Dosages and frequency are based on anecdotal accounts and bodybuilding forums.
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Men: Typical dosages for men range from 100-200 mg per day (oral). The frequency is usually daily due to its short half-life.
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Women: Dosages for women are significantly lower to minimize virilization risks, typically ranging from 25-50 mg per day (oral).
Half-Life and Detection Time
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Half-Life: The half-life of oral Methenolone Acetate is relatively short, approximately 4-6 hours. This is why it is typically taken daily or even multiple times a day.
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Detection Time: The detection time for Methenolone Acetate and its metabolites in urine is a key concern for tested athletes. The detection window for the oral form is about 4-5 weeks after the last dose, with some sources suggesting it can be detectable for longer periods.
Sterogenic, Progestogenic, and Prolactin Effects
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Estrogenic: Methenolone Acetate is a derivative of DHT and does not aromatize, so it has no estrogenic effects.
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Progestogenic: It is not a progestin and therefore has no progestogenic activity.
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Prolactin: It does not directly affect prolactin levels. It does not cause the typical prolactin-related side effects associated with progestins like nandrolone.
Pharmacological Properties
Half Life
4.8 hours
Active Dose
87%
Detection
1.00 days
Concentration
10 mg/tab
Anabolic/Androgenic Profile
Usage Effectiveness
Activity Profile
Estrogenic
None
Progestanic
None
Water Retention
None
Aromatization
No
Benefits
Dosage Recommendations
Beginner
20-40 mg/week
Intermediate
40-60 mg/week
Advanced
60-100 mg/week
Evidence-based planning resources
Dive deeper into Methenolone Acetate (Primobolan) cycle design, stacking options, and harm-reduction checklists available inside Anabolic Planner.
- Methenolone Acetate (Primobolan) compound database overviewCompare Methenolone Acetate (Primobolan) with other steroid agents in the structured compound index.
- Methenolone Acetate (Primobolan) stack and cycle templatesReview evidence-based cycle outlines, dose progressions, and PCT pairings that incorporate Methenolone Acetate (Primobolan).
- Harm-reduction guide for Methenolone Acetate (Primobolan)Refresh safety monitoring, lab work, and countermeasure strategies tailored for Methenolone Acetate (Primobolan) protocols.
Peer-reviewed reference material
Validate mechanisms, contraindications, and regulatory guidance for Methenolone Acetate (Primobolan) with trusted clinical databases.
- Methenolone Acetate clinical research on PubMedSearch peer-reviewed human and veterinary studies discussing efficacy, endocrine impact, and contraindications.
- Methenolone Acetate pharmacology via Drug Information PortalReview mechanisms, synonyms, regulatory status, and toxicology summaries from the U.S. National Library of Medicine.
Side Effects
Common
Severe
Safety Information
Liver Toxicity
Moderate
Kidney Toxicity
Low
Cardiovascular Risk
Moderate
Disclaimer: This information is for educational purposes only. Always consult with a qualified healthcare professional before using any compounds.