Mesterolone is the androgen 1-methyl-dihydrotestosterone.
Proviron is the Bayer brand name for the oral form of mesterolone.
Just as with DHT, the activity of this steroid is that of a strong androgen which does not aromatize into estrogen.
In clinical situations Proviron is generally used to treat various types of sexual dysfunction,
which often result from a low endogenous testosterone level. It can reverse problems of sexual disinterest and impotency,
and is sometimes used to increase the amount of sperm. This steroid drug does not stimulate the body to produce testosterone,
but is simply an oral androgen substitute that is used to compensate for a lack of the own body testosterone level in male bodybuilder`s.
Although this steroid is strongly androgenic, the anabolic effect of it is pretty good for bodybuilding purposes.
This is due to the fact that Proviron is rapidly reduced to inactive metabolites in muscle tissue also characteristic of dihydrotestosterone.
The belief that the anabolic nature of mesterolone indicated a tendency to block the androgen receptor in muscle tissue,
thereby reducing the gains of other more potent muscle building steroids, should likewise not be taken seriously.
In fact due to its extremely high affinity for plasma binding proteins,
Proviron increase the activity of other steroids by displacing a higher percentage into a free usable state.
Among bodybuilders, Proviron is primarily used as an anti-estrogen.
It is believed to act as an anti aromatase in the body, preventing or slowing the conversion of steroids into estrogens.
The result is comparable to anastrozole also known as Arimidex which is used to prevent the buildup of estrogen in the body.
This is in direct contrast to tamoxifen, which only blocks the ability of estrogen to bind and activate receptors in certain tissues. The anti-aromatization effect is preferred, as it is a more direct and efficient means of dealing with the problem of estrogenic side effects. Another disadvantage of tamoxifen is that if discontinued too early,
a rebound effect may occur as high serum estrogen levels are again free to take action.
This of course could mean a rapid onset of side effects such as gynecomastia.
Most actually prefer to use both Proviron and tamoxifen, especially during strongly estrogenic cycles.
With each item attacking estrogen at a different angle, side effects are often greatly reduced.
The anti-estrogenic properties of Proviron are not unique to this compound. A number of steroids have in fact demonstrated similar activity. Dihydrotestosterone and Masteron (2-methyl-dihydrotestosterone) for example have been successfully used as therapies for gynecomastia and breast cancer due to their strong anti-estrogenic effect. It has been suggested that nandrolone may even lower aromatase activity in peripheral tissues where it is more resistant to estrogen conversion (the most active site of nandrolone aromatization seems to be the liver). The anti-estrogenic effect of all of these compounds is presumably caused by their ability to compete with other substrates for binding to the aromatase enzyme. With the aromatase enzyme bound to the steroid, yet being unable to alter it and inhibiting effect is achieved as it is temporarily blocked from interacting with other hormones.
Proviron is also favored by many during contest preparations, when a lower estrogen/high androgen level is particularly sought after. This is especially beneficial when anabolic steroids like Winstrol, Anavar and Primobolan are being used alone, as the androgenic content of these drugs is relatively low. Proviron can supplement a well needed androgen, and bring about an increase in the hardness and density of the muscles. Women in particular find a single 25mg tablet will efficiently shift the androgen/estrogen ratio and can have a great impact on the physique. Since this is such a strong androgen however, extreme caution should be taken with administration. Higher dosages clearly have the potential to cause virilization symptoms quite readily. For this reason females will rarely take more than one tablet per day, and limit the length of intake to no longer than four or five weeks. One tablet used in conjunction with 10 or 20mg of tamoxifen can be even more efficient for muscle hardening, creating an environment where the body is much more inclined to burn off extra body fat (especially in female trouble areas like the hips and thighs).
The typical dosage for men is one to four 25 mg per tablets per day. This is a sufficient amount to prevent gynecomastia, the drug is often used throughout the entire cycle. As mentioned earlier, it is often combined with tamoxifen (Nolvadex) or Clomid (clomiphene) when heavily estrogenic steroids are being taken (Dianabol, testosterone etc.). Administering 50mg of Proviron and 20mg tamoxifen daily has proven extremely effective in such instances, it is quite uncommon for higher dosages to be required. And just as we discussed for women, the androgenic nature of this compound is greatly welcome during contest preparation. Here again Proviron should noticeably benefit the hardness and density of the muscle while at the same time increasing the tendency to burn off a greater amount of body fat.
Proviron is usually well tolerated and side effects (men) are rare with dosages under 100 mg per day. Above this, one may develop an excessively high androgen level and encounter some problems.
Typical androgenic side effects include:
With the strong effect DHT has on the reproductive system, androgenic actions may also include an extreme heightening of male libido. And as mentioned before, women should be careful with Proviron. It is an androgen, and as such has the potential to produce virilization symptoms quite readily. This includes, of course, a deepening of the voice, menstrual irregularities, changes in skin texture and clitoral enlargement.
Proviron is also not a c17 alpha alkylated compound, an alteration commonly used with oral anabolic/androgenic steroids. Not using this structure in the case of Proviron removes the notable risk of liver toxicity we normally associate with oral drugs. It is therefore considered a “safe” oral, the user having no need to worry about serious complications with use. This steroid in fact utilizes the same 1-methylation we see present on Primobolan (methenolone), another well tolerated orally active compound. Alkylation at the one position also slows metabolism of the steroid during the first pass although much less profoundly than 17 alpha alkylation. Likewise Proviron and Primobolan are resistant enough to breakdown to allow therapeutically beneficial blood levels to be achieved, although the overall bioavailability of these compounds is still much lower than methylated oral steroids.