Proviron — mesterolone

Proviron is Schering’s (now Bayer’s) brand name for the oral androgen mesterolone (1- methyl dihydrotestosterone). Similar to dihydrotestosterone, mesterolone is a strong androgen with only a weak level of anabolic activity. This is due to the fact that like dihydrotestosterone, mesterolone is rapidly reduced to inactive diol metabolites in muscle tissue where concentrations of the 3-hydroxysteroid dehydrogenase enzyme are high. The belief that the weak anabolic nature of this compound indicates a tendency to block the androgen receptor in muscle tissue, thereby reducing the gains of other more potent musclebuilding steroids, should likewise not be taken seriously. In fact, due to its extremely high affinity for plasma binding proteins such as SHBG, mesterolone may actually work to potentate the activity of other steroids by displacing a higher percentage into a free, unbound state. Among athletes, mesterolone is primarily used to increase androgen levels when dieting or preparing for a contest, and as an anti-estrogen due to its intrinsic ability to antagonize the aromatase enzyme.

Brand name Proviron, Mesterolone, Mesviron
Androgenic 30-40
Anabolic 100-150
Standard Testosterone propionate
Chemical Names 17beta-hydroxy-1alpha-methyl-5alpha-androstan-3-one
1-methyl-5alpha-dihydrotestosterone
Estrogenic Activity none
Progestational Activity not significant

Mesterolone history

According to company literature, Schering developed Proviron in 1934, making this is an extremely old medication as far as anabolic/androgenic steroids. Schering also states that it was the first medication put into clinical practice for the treatment of “hormone-related diseases and complaints in men.” Accordingly, mesterolone would have been developed around the same time as Methyltestosterone (1935) and Testosterone propionate (1937), which are both very old agents generally considered obsolete by today’s standards. In spite of its age, Proviron has a long history of clinical effectiveness and safety, and remains in widespread clinical use today. It is generally prescribed to males for the treatment of declining physical and mental capacity caused by age and subnormal androgen levels, low libido caused by insufficient androgen levels, hypogonadism (in pre- and post-pubescent males), and infertility (in certain situations mesterolone increases the quality and quantity of sperm).

The use of mesterolone as a fertility aid is perhaps one of the most controversial indications for this drug considering that anabolic/androgenic steroids are generally linked to infertility. It is also a use of Mesterolone that is quite often misunderstood by athletes. Mesterolone is applicable here because it is an effective androgen that offers minimal suppression of gonadotropins in normal therapeutic doses, not because it increases LH output. Absent gonadotropin suppression, the drug may supplement androgenicity necessary for sperm production. It is well understood that androgens have direct stimulatory effects on spermatogenesis, and also influence the transportation and maturation of sperm via effects on the epididymis, ductus deferens, and seminal vesicles. So the role of these hormones is not entirely suppressive. Mesterolone seems to have a unique positive influence on certain cases of male fertility because its potential stimulatory effects on sperm quantity and quality are not overridden by the suppression of gonadotropins.

Mesterolone is widely manufactured by Bayer (formerly Schering), which currently sells the drug in more than thirty countries worldwide. The most common brand name used for its sale is Proviron, although Schering/Bayer has sold the agent under other names in certain markets, including Mestoranum and Provironum. Additionally, other manufacturers have sold mesterolone over the years, appearing under such brand names as Pluriviron (Asche, Germany), Vistimon (Jenepharm, Germany), and Restore (Brown & Burke, India). In spite of its long track record of safety and efficacy, mesterolone was never approved for sale in the United States. It remains available in many Western nations, however. Bayer remains the major (almost exclusive) global supplier of mesterolone today, although on rare occasion other brands of the drug can be located.

How is Mesterolone Supplied

Mesterolone is widely available in human drug markets. Composition and dosage may vary by country and manufacturer; preparations generally contain 25 mg or 50 mg of steroid per tablet.

Structural Characteristics of Mesterolone

Mesterolone is a modified form of dihydrotestosterone. It differs by the addition of a methyl group at carbon 1, which helps protect the hormone from hepatic metabolism during oral administration. The same structural modification is also used with oral Primobolan (Methenolone) tablets. Alkylation at the one position slows hepatic metabolism of the steroid during the first pass, although much less profoundly than c-17 alpha alkylation. Mesterolone is resistant enough to breakdown to allow therapeutically beneficial blood levels to be achieved, although the overall bioavailability remains much lower than c-17 alpha alkylated oral steroids. Mesterolone also has a very strong binding affinity for Sex Hormone Binding Globulin. This may act to displace other steroids more weakly bound to SHBG into a free (active) state.

Mesterolone Side Effects (Estrogenic)

Mesterolone is not aromatized by the body, and is not measurably estrogenic. An antiestrogen is not necessary when using this steroid, as the drug is unlikely to induce gynecomastia, water retention, or other estrogen-related side effects.

Mesterolone is actually believed to act as an anti-aromatase in the body, preventing or slowing the conversion of steroids into estrogen. The result is somewhat comparable to Arimidex, although less profound. The anti-estrogenic properties of Mesterolone are not unique, and a number of other steroids have 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 androgenic and potentially anti-estrogenic effect. It has also 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 antiestrogenic 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, an inhibiting effect is achieved as it is temporarily blocked from interacting with other hormones.

Mesterolone Side Effects (Androgenic)

Mesterolone is classified as an androgenic steroid. Androgenic side effects are common with this substance, especially with higher doses. This may include bouts of oily skin, acne, and body/facial hair growth. Anabolic/androgenic steroids may also aggravate male pattern hair loss. Women are also warned of the potential virilizing effects of anabolic/androgenic steroids. These may include a deepening of the voice, menstrual irregularities, changes in skin texture, facial hair growth, and clitoral enlargement. Additionally, the 5-alpha reductase enzyme does not metabolize mesterolone, so its relative androgenicity is not affected by finasteride or dutasteride.

Mesterolone Side Effects (Hepatotoxicity)

Mesterolone is not c17-alpha alkylated, and not known to produce hepatotoxic effects; liver toxicity is unlikely.

Mesterolone Side Effects (Cardiovascular)

Anabolic/androgenic steroids can have deleterious effects on serum cholesterol. This includes a tendency to reduce HDL (good) cholesterol values and increase LDL (bad) cholesterol values, which may shift the HDL to LDL balance in a direction that favors greater risk of arteriosclerosis. The relative impact of an anabolic/androgenic steroid on serum lipids is dependant on the dose, route of administration (oral vs. injectable), type of steroid (aromatizable or non-aromatizable), and level of resistance to hepatic metabolism. Mesterolone is an oral non-aromatizable androgen, and expected to have a notable negative effect on lipids. Studies administering 100 mg of mesterolone per day to hypogonadal men for approximately 6 months demonstrated a significant increase in total cholesterol (18.8%) and LDL cholesterol (65.2%), accompanied by a significant decrease in HDL cholesterol (- 35.7%).

Mesterolone should not be used when cardiovascular risk factors preclude the use of other oral steroids.

To help reduce cardiovascular strain it is advised to maintain an active cardiovascular exercise program and minimize the intake of saturated fats, cholesterol, and simple carbohydrates at all times during active AAS administration. Supplementing with fish oils (4 grams per day) and a natural cholesterol/antioxidant formula such as Lipid Stabil or a product with comparable ingredients is also recommended.

Mesterolone Side Effects (Testosterone Suppression)

Mesterolone has a very weak suppressive effect on gonadotropins and serum testosterone. Studies show that when given in moderate doses (150 mg per day or less), significant suppression of testosterone levels does not occur.574 In studies with higher doses (300 mg per day and above), the agent strongly suppressed serum testosterone. The above side effects are not inclusive.

Mesterolone Administration (Men)

To treat androgen insufficiency, mesterolone is usually given in a dose of 1 tablet (25 mg) three times per day at the initiation of therapy. The drug is later continued at a lower maintenance dose, which usually consists of taking 1 tablet (25 mg) one to two times per day. Similar doses are used to support male fertility, usually in conjunction with other fertility drugs like injectable FSH.

The usual dosage among male athletes is between 50 mg and 150 mg of mesterolone per day, or two to six 25 mg tablets. The drug is typically taken in cycles of 6-12 weeks in length, which is usually a sufficient period of time to notice the benefits of drug therapy.

Many bodybuilders favor the use of mesterolone during dieting phases or contest preparation, when low estrogen and high androgen levels are particularly desirable. This is especially beneficial when anabolics like Winstrol, Anavar, or Primobolan are being used alone, as the androgenic content of these drugs is relatively low. Mesterolone can be effectively used here to adjust the androgen to estrogen ratio upwards, bringing about an increase in the hardness and density of the muscles, supporting libido and general sense of well being, and increasing the tendency to burn body fat. It is also commonly used (at a similar dosage) to prevent gynecomastia when other aromatizable steroids are being administered, often in conjunction with 10-20 mg per day of Nolvadex.

Mesterolone Administration (Women)

Mesterolone is not approved for use in women. This agent is not recommended for women for physique- or performance-enhancing purposes due to its strong androgenic nature and tendency to produce virilizing side effects. Some women do favor the drug, however, and find a single 25 mg tablet enough to efficiently shift the hormone balance in the body, greatly impacting the look of definition to the physique. Intake is usually limited to no longer than four or five weeks in such situations to minimize the chance of developing lasting virilizing effects. One tablet used in conjunction with 10 or 20 mg of Nolvadex can be even more efficient for muscle hardening, creating an environment here the body is much more inclined to burn off extra body fat, especially in female trouble areas like the hips and thighs. Extreme caution should be taken with such use, however.

Mesterolone Availability

Mesterolone remains widely available, the vast majority of products made by or under license from Schering (now Bayer). In reviewing some of the more popular products and changes on the global pharmaceutical market, we have made the following observations.

Bayer took control of Schering AG in December 2006. Following this acquisition, the Schering Proviron products have been transitioned over to the Bayer brand and logo.

Bayer no longer markets Proviron in Egypt. The drug remains available under the Cidoviron name, produced by the domestic firm CID (Chemical Industries Development).

Unigen markets the product Mesviron in Thailand. It contains 25 mg per tablet, and is packaged in foil and plastic strips of 10 tablets each (5 strips per box).

Due to its limited demand, mesterolone products have traditionally not been the subjects of high volume counterfeiting. When located on the black market, they can usually be trusted so long as they are properly packaged from a known manufacturer.

Proviron is produced by Swiss Remedies and available across Europe. Due to numerous fakes of this product, Swiss Remedies offers a convenient online product checker.

Magnus Pharmaceuticals makes the product Proviron primarily for the EU and UK markets. Due to fake products appearing on the market, Magnus offers an online checker that lets steroid users verify their product originality.

Bodybuilders reference

Proviron is a purely androgenic steroid with no anabolic qualities. The drug was used both as an anti-estrogen that "prevents" estrogen from being produced through the aromatization of sex steroids, and for its hardening effect upon musculature. Unlike Nolvadex (which only keeps estrogen from bonding with its receptors by blocking them), Proviron actually prevents the formation of estrogen. Due to lower estrogen levels, athletes retained less water and prevented (for the most part) the formation of gyno and female pattern fat deposits.

*If it worked perfectly, we would not see all the obvious gyno at bodybuilding shows.

Proviron was popular as a post-cycle anti-estrogen. (To keep estrogen from becoming the dominant hormone and to kick up sex drive lost due to low androgen levels) In fact, it is used in medicine as a drug to increase sperm production and eliminate sexual dysfunction in males. In some cases Proviron is prescribed to decrease flow or stop menstruation in females. For males this only replaces the androgens levels, not cures the problems of low testosterone production. Though the reader should note that the decrease in circulatory estrogen in itself promotes increased HPTA activity. At one time Proviron was commonly used year round by many appearance oriented athletes to maintain hardness. Now, according to recent polls, more athletes are using ephedrine and Clenbuterol to replaced Proviron for this purpose. By the way, frequent and sometimes painful erections are side effects of Proviron use. (So?) Actually, an erection that lasts days can cause permanent damage and erectile problems.

*I commonly extorted another physiological response provided from the use of this drug. Proviron possesses the ability to bind SHBG at a high rate. By doing so other coadministered AAS (or endogenous testosterone) remained in an unbound/free state. This resulted in greater anabolic and androgenic activity realization with lower dosage requirements.

As to dosages, males "usually" administered 25-200mg daily and often combined it with Nolvadex (*See Nolvadex). Women athletes commonly reported virilizing side effects when employing Proviron. It should be noted that most women who reported this side effect also co-administered other androgens. At a dosage of 25-50-mg daily combined with Nolvadex most reported good results and few side effects. Teslac was believed to be a superior anti-aromatase drug (which shuts down estrogen production) but few considered it cost effective. 50mg Proviron and 250-1000mg Teslac, or 150mg Proviron and 20mg Nolvadex daily, was said to almost totally suppress estrogens. (Both during steroid cycles and after these dosages were quite effective).

Anabolic Steroid Guide reference

Proviron is a synthetic, orally effective androgen which does not have any anabolic characteristics. Proviron is used in school medicine to case or cure disturbances caused by a deficiency of male sex hormones. Many athletes, for this reason, often use Proviron at the end of a steroid treatment in order to increase the reduced testosterone production. This, however, is not a good idea since Proviron has no effect on the body's own testosterone production but as mentioned in the beginning-only reduces or completely eliminates the dysfunctions caused by the testosterone deficiency. These are, in particular, impotence which is mostly caused by an androgen deficiency that can occur after the discontinuance of steroids, and infertility which manifests itself in a reduced sperm count and a reduced sperm quality. Proviron is therefore taken during a steroid administration or after discontinuing the use of the steroids, to eliminate a possible impotency or a reduced sexual interest. This, however, does not contribute to the maintenance of strength and muscle mass after the treatment. There are other better suited compounds for this (see HCG, Clomid, and Teslac). For this reason Proviron is unfortunately considered by many to be a useless and unnecessary compound.

You should be aware that Proviron is also an estrogen antagonist which prevents the aromatization of steroids. Unlike the antiestrogen Nolvadex which only blocks the estrogen receptors (see Nolvadex) Proviron already prevents the aromatizing of steroids. Therefore gynecomastia and increased water retention are successfully blocked. Since Proviron strongly suppresses the forming of estrogens no rebound effect occurs after discontinuation of use of the compound as is the case with, for example, Nolvadex where an aromatization of the steroids is not prevented. One can say that Nolvadex cures the problem of aromatization at its root while Nolvadex simply cures the symptoms. For this reason male athletes should prefer Proviron to Nolvadex. With Proviron the athlete obtains more muscle hard-ness since the androgen level is increased and the estrogen concentration remains low. This, in particular, is noted positively during the preparation for a competition when used in combination with a diet. Female athletes who naturally have a higher estrogen level often supplement their steroid intake with Proviron resulting in increased muscle hardness. In the past it was common for body-builders to take a daily dose of one 25 mg tablet over several weeks, sometimes even months, in order to appear hard all year round. This was especially important for athletes' appearances at guest performances, seminars and photo sessions. Today Clenbuterol is usually taken over the entire year since possible virilization symp-toms cannot occur which is not yet the case with Proviron. Since Proviron is very effective male athletes usually need only 50-mg/ day which means that the athlete usually takes one 25 mg tablet in the morning and another 25 mg tablet in the evening. In some cases one 25 mg tablet per day is sufficient. When combining Proviron with Nolvadex (50 mg Proviron/day and 20 mg Nolvadex/day) this will lead to an almost complete suppression of estrogen. Even better results are achieved with 50 mg Proviron/ day and 500 - 1000 mg Teslac/day. Since Teslac is a very expensive compound (see Teslac) most athletes do not consider this combination.

The side effects of Proviron in men are low at a dosage of 24 tablets/day so that Proviron, taken for example in combination with a steroid cycle, can be used comparatively without risk over several weeks. Since Proviron is well tolerated by the liver, liver dysfunctions do not occur in the given dosages. For athletes who are used to acting under the motto "more is better" the intake of Proviron could have a paradoxical effect. The most common side effect of Proviron is a distinct sexual overstimulation and in some cases continuous penis erection. Since this condition can be painful and lead to possible damages, a lower dosage or discontinuing the compound are the only sensible solutions. Female athletes should use Proviron with caution since possible androgenic side effects cannot be excluded. Women who want to give Proviron a try should not take more than one 25 mg tablet per day. Higher dosages and periods of intake of more than four weeks considerably increase the risk of virilization symptoms. Female athletes who have no difficulties with Proviron obtain good results with 25 mg Proviron/ day and 20 mg Nolvadex/day and, in combination with a diet, report an accelerated fat breakdown and continuously harder muscles.

Proviron is one of the very few steroid hormones which is still sufficiently available. The usual price is about $1 per tablet on the black market. All Proviron tablets have one thing in common: they are all indented and on the back have the stamp AX, surrounded by a hexagon.

Newbies Research Guide reference

Proviron is not technically classified as an anti-aromatase, but is an oral androgenic steroid. Specifically it contains a derivative of the potent steroid dihy- drotestosterone, differing only by the addition of 1 methylation (the same alteration used to increase the oral efficacy of Primobolan). Its use as an antiaro- matase stems from studies showing a nonaromatizing androgen such as dihydrotestosterone may interfere with this enzyme reaction. It is believed to interfere with aromatase by competing with an aromatizable steroid such as testosterone for binding to the enzyme site. With dihydrotestosterone (or Proviron) interact- ing with this enzyme, yet producing no reaction, the enzyme is temporally prevented from altering other hormones, and an anti-estrogenic effect is achieved. Overall however, Proviron is much less reliable than any one of the mentioned antiestrogens or aromatase inhibitors. Though it may add some benefit when taken concurrently with a drug such as tamoxifen (though in such a case tamoxifen would be doing most of the work), I don’t think that it is potent enough as an aromatase inhibitor to recommend using along during strong cycles. As with testolactone, Proviron also has the added drawback of being a controlled sub- stance. Likewise it is often harder to obtain than many of the other agents.

References

Wlliam Llewellyn (2011) - Anabolics
L. Rea (2002) - Chemical Muscle Enhancement Bodybuilders Desk Reference
Anabolic Steroid Guide
Newbies Research Guide

Back to Steroid profiles

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