Primobolan (Injectable)
Methenolone Enanthate · Primo
Injectable methenolone enanthate; very long half-life, mild profile. Peak calibrated.
Key takeaways
- Injectable DHT derivative (methenolone enanthate); among the mildest injectables.
- ~10.5-day half-life; twice-weekly injection, slow build to steady state.
- No aromatization, no 17-alpha-alkylation, not hepatotoxic.
- Slow, modest gains; counterfeiting is rampant, so source verification matters.
Overview
What it is
Primobolan injectable (methenolone enanthate) is a DHT-derived injectable originally used for wasting conditions and pediatric underweight. It binds the androgen receptor with low androgenic potency, doesn't aromatize, and can't be further 5-alpha-reduced, which produces one of the mildest side-effect profiles of any injectable.
Pharmacokinetics
The enanthate ester gives a ~10.5-day half-life with ~73% bioavailability, so twice-weekly injection keeps levels smooth. Steady state takes several weeks, and gains, when they come, are slow and lean.
Harm reduction
Not hepatotoxic (no 17-alpha-alkylation), no estrogenic effects, and comparatively gentle HPTA suppression at moderate doses. The realistic risks are androgenic (hair, skin), a lipid hit, and one of the highest counterfeiting rates of any AAS.
Reported dosing protocols
Protocols reported in research literature and clinic/community use — informational context, not a dosing recommendation.
| Use case | Dose | Route | Frequency | Duration |
|---|---|---|---|---|
| Wasting / underweight (historical clinical) | 100–200 mg weekly | IM | 1× weekly | Weeks–months |
| Cutting / lean gain (community) | 200–400 mg weekly | IM | 2× weekly | 8–12 weeks |
Pharmacokinetic summary
- Model tier
- Simple (t½ + F, Tmax estimated)
- Half-life
- 11 days
- Cmax
- 88.9 ng/dL
- Bioavailability
- 73%
- Typical dose
- 200–400 mg
Harm reduction
- Aromatizes
- No
- DHT derivative
- Yes
- Injection frequency
- 2×/week
Frequently asked questions
Why is Primobolan considered clean?
It doesn't aromatize, isn't 17-alpha-alkylated, and has low androgenic potency, so the usual estrogenic and hepatic problems don't apply. Clean doesn't mean free: lipids still shift, hair loss can accelerate, and suppression still happens, just more gently.
Is Primobolan often faked?
Yes, it's among the most counterfeited AAS because genuine methenolone is expensive to produce. Fakes are commonly testosterone or cheaper steroids relabeled. Lab testing or trusted sourcing is the practical safeguard.
Does Primobolan need a testosterone base?
Most reported protocols include one. Methenolone suppresses endogenous testosterone, and without a base, low-testosterone symptoms tend to show up mid-cycle. Suppression is milder than with most injectables at moderate doses, but it's still real.
References
- Llewellyn reference — Cmax calibrated to ng/dL serum peak.
- Llewellyn, ANABOLICS (methenolone reference) — Reference text behind the PK calibration; human PK literature is otherwise sparse.
Related compounds
Primobolan (Oral)
Oral methenolone acetate; mild, low-side, short half-life. Simple model — peak calibrated.
Testosterone Enanthate
Long-acting testosterone ester; the most common TRT and cycle base. Reaches steady state in ~5 weeks.
Testosterone Cypionate
Standard US TRT ester with a slightly longer release tail than enanthate. Steady state ~4–5 weeks.
Protocols featuring Primobolan (Injectable)
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