Overview
Proviron is an oral anabolic-androgenic steroid. 1-methyl DHT derivative. As a 17-alpha-alkylated compound, it passes through the liver intact, enabling oral bioavailability.
With a half-life of ~12 hours, Proviron requires daily administration in most observed protocols. Taken orally, it has a bioavailability of approximately 3% via its primary route.
Very low oral bioavailability (~3–5%). Not 17-alpha-alkylated. Half-life approximately 12 hours. Binds strongly to SHBG. One-compartment model.
Mechanism of Action
Proviron's pharmacological activity involves the following key pathways:
Androgen Receptor Binding
Proviron binds to androgen receptors to initiate anabolic signaling cascades in muscle tissue and other androgen-responsive cells.
17-Alpha Alkylation
The 17-alpha-alkyl group prevents first-pass hepatic degradation, enabling oral bioavailability. This structural modification is what makes oral administration viable.
Non-Aromatizing
Proviron does not undergo direct aromatization to estrogen, a distinguishing property among oral anabolics.
Dosing Protocols
The following protocols represent commonly observed dosing patterns. These are observational summaries, not recommendations.
Dose
25 mg/day
Route
Oral
Frequency
Once daily
Duration
4-8 weeks
Dose
75 mg/day
Route
Oral
Frequency
Once daily
Duration
4-8 weeks
Frequently Asked Questions
What is Proviron and how does it work?
Proviron (Mesterolone) is an orally active androgen and anabolic steroid derived from dihydrotestosterone (DHT). It has strong androgenic properties but relatively weak direct anabolic activity in skeletal muscle due to rapid inactivation by the 3α-hydroxysteroid dehydrogenase enzyme. Its primary value lies in its exceptionally high binding affinity for sex hormone-binding globulin (SHBG), which can increase the proportion of free, bioavailable testosterone in circulation.
What is the half-life of Proviron?
Proviron has an elimination half-life of approximately 12 hours, with peak plasma concentrations reached within 1–3 hours after oral administration. This half-life supports twice-daily dosing to maintain stable blood levels throughout the day. The compound is rapidly absorbed and metabolized.
How does Proviron affect free testosterone and SHBG?
Mesterolone has one of the highest binding affinities for SHBG among all anabolic steroids — reported at several times that of testosterone. By occupying SHBG binding sites, it displaces testosterone that would otherwise be bound and inactive, effectively increasing the ratio of free (bioavailable) testosterone without raising total testosterone levels. This mechanism is central to its use as an adjunct compound.
What are the common dosing protocols for Proviron?
In clinical settings, Mesterolone has been administered at 25–150 mg per day, typically divided into 2–3 doses. For performance enhancement contexts, 25–75 mg per day is the most commonly observed range. It is frequently used at 25–50 mg daily alongside testosterone replacement therapy, or at 50–75 mg daily during cutting-oriented protocols.
Does Proviron convert to estrogen?
Proviron does not aromatize to estrogen. As a pure DHT derivative, it lacks the structural requirements for conversion by the aromatase enzyme. Additionally, Mesterolone has been observed to have mild anti-estrogenic activity by competing with other substrates for aromatase binding, though this effect is modest compared to dedicated aromatase inhibitors.
What compounds are commonly stacked with Proviron?
Proviron is most commonly used as an adjunct rather than a primary compound. It is frequently paired with Testosterone Enanthate or Testosterone Cypionate during TRT or blast protocols to enhance free testosterone. It is also commonly added to cutting stacks containing Masteron or Anavar. Cycle durations of 8–12 weeks are typical when used as a stack component.