Proviron (mesterolone) by Jintani Labs

Proviron (mesterolone) is 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 muscle-building 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 antiestrogen due to its intrinsic ability to antagonize the aromatase enzyme.

Mesterolone is a modified form of dihydrotestosterone. It differs by the addition of a methyl group at carbon, 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/1o This may act to displace other steroids more weakly bound to SHBG into a free (active) state.

Mesterolone is not aromatized by the body, and is not measurably estrogenic. An anti-estrogen 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 antiaromatase 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 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 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.

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

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 (18.80/0) and LDL cholesterol (65.20/0), accompanied by a significant decrease in HDL cholesterol (-35.7°;6).

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 anabolic steroids 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.

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 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 where 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.