Proviron is an androgenic steroid derived from DHT, with antiestrogenic properties, class 1 (binds strongly to the androgen receptor, AR), and with good affinity to SHBG.

Proviron or Mesterolone is an anabolic steroid devoid of anabolic properties, even with an anabolism / androgenicity rating: 100-150 / 30-40. Despite the weak or nonexistent anabolic power Proviron is very popular with bodybuilders for its antiestrogenic properties, and also known for improving libido, possibly for its ability to bind very well to SHBG, increasing free testosterone.

Proviron is not only the weakest steroid in anabolic power, it is also among the mildest steroids in side effects, with difficult or even rare reports of problems with this drug. Mesterolone does not convert to DHT and estrogen, and can be considered a weak aromatase inhibitor: ”The mechanism by which it has some effectiveness in this regard is to weakly bind to the estrogen receptor without activating it, and the aromatase enzyme. In the first case, this partially reduces the number of estrogen receptor sites currently available for binding, thereby reducing estrogenic activity. In the second case, some fractions of aromatase molecules at any given time are not available to bind and convert testosterone, its binding sites to be occupied with mesterolone “(Bill Roberts). Some authors (Anthony Roberts) compare Proviron to Masteron, calling it "oral Masteron", but in fact Masteron is a much superior drug in anabolic power, with mesterolone showing no significant activity in this regard.

Despite being an oral drug, proviron is not an alpha-alkylated, but a 1-methylated, so it has low hepatoxicity. The therapeutic doses of proviron vary from 50 to 75mg per day, but even at high doses (100-150mg per day) it does not cause suppression of the HPT axis. Even though it is not able to raise levels of LH and FSH, proviron is widely used by some athletes and users in CPT, due to its possible ability to improve libido (increasing free testosterone, due to its binding to SHBG) without suppressing the HPT axis. Its antiestrogenic properties and strong binding to the SHBG causes proviron to increase the power of the cycle and also improve the aesthetic quality of the gains. Proviron has a half-life of 12 to 13 hours, so if you are going to take more than 1 tablet, divide the doses during the day, every 8 or 12 hours.

Female athletes like to use this drug in a contest diet combined with some more anabolic drug to have a drier and denser shape. The doses for women are in the range of 25 to 50 mg per day, and the risks of virilization are low or even non-existent.

Due to its limited anabolic and fat-burning power, the effectiveness of Proviron is quite questionable. Even for therapeutic use, used to treat infertility (oligospermia) and androgenic deficiency symptoms, the studies are quite controversial, and many authors, such as Michael Scally, consider that proviron is of no use in this regard.

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