controversy surrounds Proviron (mesterolone)

Mesterolone has within our sport many purposes and its use and effect is debated and dicussed in many threads. What lots of bodybuilders don't realise is that the usage of all means is dependant, let me explain.

When you use a gram of testosterone you have a big chance that it will convert to a more aggressive and harsher compound, namely DHT. You most likely use un anti-estrogen like Arimidex.

When on the other hand you use a gram of nandrolone, this will convert into a milder compound (DHN) by the same enzym (5-alpha-reductase). Use of Arimidex etc is useless and you should use Nolvadex and…proviron to prevent the side-effect we call in slang “deca-dick” which is a loss in libido.

Also hotly debated is Provirons use in PCT-HRT-bridging. PCT (post cycle therapy) is meant to avoid a crash after you stop using steroids.

Bridging is the use of certain means some bodybuilders take between 2 cycles.

There is no advantage of Arimidex or Femara over Proviron when it comes to control of estrogenic side effects. On the contrary, everything to estrogen largely suppressed, the only damage health rather than improve.

Arimidex (anastrozole), Femara (letrozole) are very effective in suppressing estrogen and thus avoid these side effects. They are so effective, that too little estrogen is left to the health and growth of the body.

Therefore, these drugs are only suitable to cure certain types of cancer, NOT reduce aromatization of AAS where the disease is much less harmful than the side effects of the drug.

Where anastrozole was already shown to be very negative on the  lipidbalance HDL/ LDL cholesterol in the liver and blood, letrozole is even 2.5 times worse (1).

Letrozole has also studies a negative effect on bone density (2). It suppresses estrogen (E) to a high degree:

Quote: “In postmenopausal women, letrozole commonly suppresses circulating estradiol and estrone Concentrations or to below the sensitivity limit of the assay to measure em overused. (2) “

The selective estrogenic receptor modulators (SERMs) Nolvadex (tamoxifen), exemestane, raloxifene in the contrary improve bone density and cholesterol unlike the anti-estrogens and aromatase blockers, mainly by selective binding to the ER. Where anastrozole and letrozole will reduce your health, nolvadex will improve your health while the result is the same for preventing the negative estrogenic side effects (3).

Proviron (mesterolone) during a lowdosed cycle should always be preferred over both Arimidex, Nolvadex or Letrozole.

Mesterolone improved the libido in several studies, without testosterone suppression (4), is a very good anti-depressant (5), binds strongly to SHBG and allows more free testosterone to the AR in muscle tissue (more AR-User Related muscle growth in test cures), because low mesterolone (especially in low dose), the AR reaches gives little or no androgenic side effects such as enlarged prostate, body hair growth, MPB (male pattern baldness), acne (some very sensitive men will of course an increase in cures but rarely with proviron alone).

Not backed up by scientific studies, but real life expiriences by some bodybuilders with proviron, is that it provides  muscle hardness, it avoids fluid retention or or to a certein account decreases it,  to some degree prevents gyno, and in general combats feminization by reducing excess circulating estrogen. Moreover, proviron has little negative  effect on IGF-1, unlike anastrozole.

Estrogenic effects:

- (SC) fluid retention

- Increase in blood pressure

- Bitch tits

- Depression

- Decreased libido

- increase in local bodyfat

Conclusion: During a cycle proviron is always preferable over a non-steroidal aromatase blocker as the benefits for health and muscle growth are bigger. Nolvadex is most suitable for fighting local estrogenic side effects such as breast swelling with a positive effect on cholesterol as opposed to letrozole and anastrozole.

To combat excess moisture  an aromatase blocker is a bad idea, because the disease is less severe than the side effects of the drug. Fluid retention can be fought with more selective agents without adverse effects on health (aldosterone blockers).

Those who want a worry-free cycle, can combine a small dose proviron in combination with a light dose of nolvadex. ( like50mg proviron  and 20mg Nolva/day) for most users, this would suffice to uphold libido and prevent  estrogenic side effects. This has minimal negative consequences for the health of the user.

If estrogenic effects still do occur in a large degree (gyno) than you can increase the dose of  Nolvadex. (40-50mg/dag for 4-7 days)

What is the role of mesterolone in increasing the sperm count  and motility and what is the mechanism by which it increases?

In order to understand this, one must initially review how and why testosterone is produced.  Gonadotrophin releasing hormone (GRH) is the hormone that controls reproductive function.  It is produced and released by a part of the brain called the hypothalamus and in turn controls the production and release of luteinising hormone (LH) and follicle stimulating hormone (FSH) (called gonadotrophins) from the adjacent pituitary gland.

LH acts with FSH to stimulate testosterone production, secreted by the interstitial cells of the testis and responsible for triggering the development of sperm and of many sexual characteristics such as the changes that occur during puberty in the penis and testicles.  Mesterolone is indicated in the treatment of testosterone deficiency or male infertility associated with malfunction of the hypothalamus, pituitary or testicles.  The drug is administered orally and the initial recommended dosage is three or four 25mg tablets daily for several months, followed by maintenance therapy of two to three tablets (50-75mg) daily.

It is not recommended in children and contraindicated when there is a history of previous or existing liver tumours, or in the presence of prostate cancer, as it may stimulate its growth.

Mesterolone's molecular structure gives it special properties that set it apart from testosterone and all the drugs derived from testosterone that are used for this type of therapy, in that it is not broken down by the body (metabolised) to oestrogen. This difference almost certainly accounts for the findings that, in its usual therapeutic dosage in normal men, mesterolone does not significantly depress the release of gonadotrophins from the pituitary.

Therefore sperm production (spermatogenesis) is unimpaired by mesterolone when compared with other drugs used in this area, which suppress and therefore replace the body's natural (endogenous) testosterone.  In other words, Mesterolone supplements ones natural testosterone.

It’s by lots of bodybuilders believed that Proviron is all androgenic and therefore will suppress HPTA and therefore can’t be used in PCT.

Updated later

a few relevant scientific studies:

Mesterolone administration produced no changes in steroids, thyroid hormones, gonadotropins nor PRL. Varma TR, Patel RH. Int J Gynaecol Obstet. 1988 Feb;26(1):121-8.

Department of Obstetrics & Gynaecology, St. George's Hospital Medical School London, U.K.

Two hundred fifty subfertile men with idiopathic oligospermia (count less than 20 million/ml) were treated with mesterolone (100-150 mg/day) for 12 months. Seminal analysis were assayed 3 times and serum follicle stimulating hormone (FSH) luteinizing hormone (LH) and plasma testosterone were assayed once before treatment and repeated at 3, 6, 9 and 12 months after the initiation of treatment. One hundred ten patients (44%) had normal serum FSH, LH and plasma testosterone, 85 patients (34%) had low serum FSH, LH and low plasma testosterone. One hundred seventy-five patients (70%) had moderate oligospermia (count 5 to less than 20 million/ml) and 75 patients (30%) had severe oligospermia (count less than 5 million/ml). Seventy-five moderately oligospermic patients showed significant improvement in the sperm density, total sperm count and motility following mesterolone therapy whereas only 12% showed improvement in the severe oligospermic group. Mesterolone had no depressing effect on low or normal serum FSH and LH levels but had depressing effect on 25% if the levels were elevated. There was no significant adverse effect on testosterone levels or on liver function. One hundred fifteen (46%) pregnancies resulted following the treatment, 9 of 115 (7.8%) aborted and 2 (1.7%) had ectopic pregnancy. Mesterolone was found to be more useful in patients with a sperm count ranging between 5 and 20 million/ml. Those with severe oligospermia (count less than 5 million) do not seem to benefit from this therapy.PMID: 2892728 [PubMed - indexed for MEDLINE]

Effect of non aromatizable androgens on LHRH and TRH responses in primary testicular failure.

Spitz IM, Margalioth EJ, Yeger Y, Livshin Y, Zylber-Haran E, Shilo S.

We have assessed the gonadotropin, TSH and PRL responses to the non aromatizable androgens, mesterolone and fluoxymestrone, in 27 patients with primary testicular failure. All patients were given a bolus of LHRH (100 micrograms) and TRH (200 micrograms) at zero time. Nine subjects received a further bolus of TRH at 30 mins. The latter were then given mesterolone 150 mg daily for 6 weeks. The remaining subjects received fluoxymesterone 5 mg daily for 4 weeks and 10 mg daily for 2 weeks. On the last day of the androgen administration, the subjects were re-challenged with LHRH and TRH according to the identical protocol. When compared to controls, the patients had normal circulating levels of testosterone, estradiol, PRL and thyroid hormones. However, basal LH, FSH and TSH levels, as well as gonadotropin responses to LHRH and TSH and PRL responses to TRH, were increased.

1. Eur J Cancer. August 2001, 37 (12) :1510-3

2. J Steroid Biochem Mol Biol. Oct 2003, 87 (1) :35-45.

3. Oncology (Huntingt). 2003 May, 17 (5) :652-9, 659 discussion, 662, 666 passim

4. Wien Klin Wochenschr. 1980 March 28, 92 (7) :243-7

5. J Clin Psychiatry. January 1985, 46 (1) :6-8.