Methenolone Enanthate — Primobolan 100 by Dragon Pharma
Primobolan 100 is Dragon Pharma's formulation of injectable Methenolone Enanthate at 100mg/ml — the most commonly referenced "mild" injectable AAS in bodybuilding and arguably the most famous lean-mass compound in the sport's history. Primobolan (Methenolone) occupies a unique pharmacological position: it does not aromatise, does not convert significantly via 5-alpha-reductase, produces minimal HPG axis suppression relative to other AAS, and uniquely among non-17-alkylated injectable AAS, its base compound (Methenolone) is orally bioavailable by its own structure — not by alkylation.
Also searched as: Methenolone Enanthate 100mg, Primobolan 100, Primo injection, Primobolan Dragon Pharma.
Primobolan's Unique Pharmacological Properties
Understanding what makes Primobolan genuinely distinctive from other injectables requires examining several specific properties simultaneously:
- No aromatisation: Methenolone does not convert to estrogen — no water retention, no gynecomastia risk from the compound itself, no AI required for Primobolan-only cycles
- Minimal 5-AR conversion: Unlike testosterone which converts strongly to DHT via 5-alpha-reductase, Methenolone undergoes only minor 5-AR metabolism. Hair loss and prostate stimulation risk are significantly lower than testosterone at equivalent anabolic doses
- Intrinsic oral bioavailability: Methenolone base (without ester) is itself orally bioavailable — an extremely unusual property for a non-17-alkylated compound. The oral Primobolan (Primobolan Acetate tablets) is not hepatotoxic for this reason — it does not require 17-alpha-methylation to survive first-pass metabolism. The injectable Enanthate ester extends half-life while preserving this non-hepatotoxic profile
- Reduced HPG suppression: Multiple studies and clinical observations suggest Methenolone suppresses LH and FSH less completely than testosterone or 19-nor compounds at equivalent anabolic doses — making it the only AAS genuinely used in some TRT-adjacent protocols where partial axis maintenance is desired
The HPG Suppression Distinction — Why Primo Is Different
This is Primobolan's most clinically interesting and least-explained property:
- All AAS suppress the HPG axis through androgen receptor-mediated negative feedback — reducing GnRH, LH and FSH to varying degrees
- Methenolone's relatively weak androgen receptor binding affinity (lower than testosterone) produces proportionally less negative feedback on the hypothalamic-pituitary axis — particularly at doses in the 200-400mg/week range
- Some clinical evidence and significant anecdotal bodybuilding experience suggests that Primobolan at moderate doses preserves LH and FSH secretion to a measurable degree — meaning natural testosterone is not completely eliminated during a Primo cycle, unlike with Testosterone, Trenbolone or Nandrolone
- This partial axis preservation has two practical implications: recovery post-cycle is typically faster and easier than from more suppressive compounds; and some users run Primobolan as an addition to TRT without fully eliminating natural testicular function on top of replacement therapy
The "Arnold's Drug" History
Primobolan's historical reputation elevates it beyond its modest anabolic ratio and warrants explanation:
- Primobolan (manufactured by Schering as the original pharmaceutical product) was widely associated with Golden Era bodybuilding — Arnold Schwarzenegger is the most frequently cited user, based on references in various interviews and publications from the 1970s. Whether this specific attribution is fully accurate, the association is documented enough to have been widely reproduced
- Schering's original pharmaceutical Primobolan Depot (Methenolone Enanthate) was manufactured in Germany and widely available by prescription in Europe into the 1990s — its legitimate pharmaceutical history distinguishes it from entirely underground compounds
- The reputation has maintained Primobolan's premium pricing: it commands significantly higher cost per milligram than compounds with equivalent or superior anabolic ratios, reflecting its status and limited supply
Effects and Benefits
- Lean, dry muscle gains without water retention — no aromatisation means gains are quality mass only
- Minimal androgenic side effects — lower hair loss and prostate stimulation risk than testosterone
- Immune system support — documented in original pharmaceutical literature; Methenolone was used medically for immune deficiency conditions
- Faster HPG recovery post-cycle compared to more suppressive compounds
- No hepatotoxicity — non-alkylated, injectable delivery, inherently non-hepatotoxic
Dosage and Administration
| Use Case | Weekly Dose | Frequency | Cycle Length |
|---|---|---|---|
| Cutting / lean mass | 400–600 mg/week | Twice weekly | 10–16 weeks |
| Advanced / Golden Era protocol | 600–1000 mg/week | Twice weekly | 10–16 weeks |
Primobolan's modest anabolic ratio (88) means meaningful effects require higher weekly doses than compounds with stronger AR binding — 400mg/week is the practical minimum for performance use. At 100mg/ml, this requires 4ml per week — making the 200mg/ml formulation more economical for higher-dose protocols. Twice-weekly injection maintains stable levels from the ~10-day Enanthate half-life.
Side Effects
- HPG suppression — present even at Primobolan's reduced suppression level; Post Cycle Therapy required after standalone cycles
- Mild androgenic effects — acne and hair loss risk significantly lower than testosterone but present in predisposed individuals
- No aromatisation — no estrogenic side effects from Primobolan itself; if stacked with testosterone, estrogen management from the testosterone component applies
- No hepatotoxicity
Building a Cycle Around Primobolan 100
- Enantat 250 as testosterone base — the classic Testosterone + Primo stack; Primo handles lean mass quality while testosterone covers androgenic base and higher anabolic load
- Masteron 200 — paired with Primobolan for a fully non-aromatising lean mass and hardness combination
- Primobolan 200 — for users running 400-600mg/week who prefer fewer injections at higher concentration
- Clomid or Nolvadex for PCT
"Primobolan 100 is the entry-point concentration for Methenolone Enanthate — suited to protocols in the 200-400mg/week range where injection volume per dose remains manageable at 1-2ml twice weekly."
Storage and Handling
Store Primobolan 100 at room temperature away from direct sunlight and heat. Use sterile technique for every draw.
