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Masteron as an Anti-Estrogen

By Anthony Roberts, author of Anabolic Steroids - The Ultimate Research Guide

Discussion of pharmaceutical agents below is presented for information only. Nothing here is meant to take the place of advice from a licensed health care practitioner. Consult a physician before taking any medication.

I know it must seem like I sit around all day trying to find new uses for old drugs, but in this case, nothing could be further than the truth. Before I get into how and why you can use Masteron as an Anti-Estrogen, I’ll tell you a bit about where this idea came from, and why I’m telling you about it. And yes, this works in real life, not just on paper - I’ve used it and seen it used for this purpose successfully by several athletes.

A few years ago, I wrote my first piece on Masteron (Drostanolone Propionate), and discovered what its clinical use actually was: Reduction of breast cancer tumors, and as hormonal treatment of breast cancer. Well…the long version of that is that Masteron is an androgenic, anabolic steroid, used as an agent used to prevent or inhibit the growth of cancerous tumors. 

Then, in one of those weird "duh" moments, I realized that gynocomastia, mastectomy, and Masteron all had that similar word root. You’d think that having an English degree would have helped me notice this fact sooner…anyway, I wrote the profile and didn’t think much about it anymore. I was then contacted by the owner of an underground lab, and asked why Masteron was always produced with a propionate ester, and whether it would be ok with a longer ester. This began another long period of research for me into Masteron. Well, I found out that Masteron would be fine with a longer ester, but I actually had a chance to test it out with that particular ester before it hit the market...I was still standing after 3 weeks on it, so it was produced en masse (as a side note that particular Underground Lab still produces it and it’s one of their better selling products). 

So here I was with all of this research on Masteron and nothing to do with it. Well, after I took another look at the compound, a couple of things struck me. The first that struck me is that Masteron is made for women! Yeah…go back and read that again if you have to. Masteron is one of the few steroids that were actually created with women in mind, not men, and it’s the one that most people tell women to avoid! And the other thing that I noticed right away was that it is used for treatment of breast cancer. In particular, it’s used for the treatment of estrogen dependant breast tumors. By now, I’m sure you see where I’m going with this…Nolvadex is used clinically for this same purpose, as is Arimidex, Femera, Aromasin (a steroidal Aromatase Inhibitor), and Teslac (a steroid, technically). That’s some good company to be in, if you’re a steroid. But interestingly, Teslac is actually a steroid also, and Aromasin is a Steroidal Aromatase Inhibitor. So why can’t a "real" steroid do the same job at preventing breast cancer? Well, the answer is that it can!

To understand why Masteron can be used as an anti-estrogen, first we need to know that it’s derived from DHT. Why is this important?

This is important because DHT directly inhibits estrogenic activity on tissues. It is possible that it does this, possibly by acting as a competitive antagonist to the estrogen receptor or by decreasing estrogen receptor binding. Either way, it has multiple hypothesized mechanisms of action in some tissues. It has also been hypothesized that DHT actually suppresses estrogen’s effects not by inhibition of synthesis of estrogen receptor, but by (get ready…big words coming up) decreasing estrogen-induced RNA transcription at some point after the actual estrogen receptor binding has occurred. This means, in much simpler terms, that the estrogen gets to the receptor, but just doesn’t do its job (1). This means you can take steroids that convert to estrogen (called aromatizable steroids) and not worry about that estrogen possibly making you retain water, gain fat, or watch "Desperate Housewives." Also, this could mean that the antiestrogenic effect of DHT is mediated by an androgen receptor mediated mechanism.

In fact, DHT has been shown to prevent the estrogen-dependent augmentation of the progesterone receptor in human breast cancer cells. And, not to be redundant, but it’s important to remember that virtually all of the anti-estrogens we use to control gyno and water retention are also used to treat breast cancer. So, now we know have observed that androgens are capable of inhibiting both the estrogenic induction and the ongoing stimulation of PRc synthesis, but have no apparent effect upon basal concentrations of this receptor. Dihydrotestosterone (DHT) demonstrates a very high degree of inhibition of estrogen in human breast cancer cells. (2). But it’s not just DHT that does this; its metabolites have been shown to inhibit aromatization itself; DHT, androsterone, and 5alpha-androstandione are all potent inhibitors of the formation of estrone from androstenedione. In fact, it's so potent at reducing estrogen that transdermal DHT gel applied to the affected area has been used to treat gynocomastia (3). DHT is such a potent anti-estrogen that it been even been used to increase height in children with short stature, and since it’s been determined that this increase is not due to GH-mediated effects, it was strongly suggested that DHT’s anti-estrogenic effects are the mechanism by which it can increase height (4) Of course, I suspect I don’t need to tell you that DHT is structurally incapable or converting to estrogen…

So all of this tells us that DHT will certainly have beneficial effects on keeping our estrogen in check, but what about Masteron? Can it be used as effectively? Well, let’s take a look at what Masteron actually is, relative to DHT. But before we can do that, I think a quick explanation of DHT is in order first. Don’t worry; I’ll make it as brief and painless as possible. 

DHT is actually the result of testosterone interacting with the 5alpha-reductase (5a-R) enzyme. This enzyme is present in the scalp, prostate, external genitalia, and other places. As far as I can see, it apparently exists for the sole purpose of converting a steroid with a double bond between carbon 4 and carbon 5 to one with a single bond between them, and subsequently adding a hydrogen atom to each carbon. This process is called (of course) 5alpha-reduction.





So now we know how testosterone becomes Dihydrotestosterone. And everything would be great if this is the only thing that happened to our good old friend testosterone, because as you may already know, DHT is a far more potent androgen than testosterone. But, unfortunately, this is not the end of the story, because DHT is largely deactivated by the enzyme 3-alpha Hydroxysteroid Dehydrogenase (3bHSD), which is mainly present in skeletal muscle.

For our purposes here, we’re only going to be concerned with one particular action of this enzyme. It can either converts a steroid with a keto group on position 3 of the steroid to one with a hydroxy group in that position, thus converting DHT is to androstanediol. This conversion is part of reason DHT alone has not proven to be a very effective muscle builder, as androstanediol is not going to be very anabolic at all. If you look off to the left of the following molecular diagram, and compare it to the one above for DHT, you’ll notice that the "O" (oxygen) has been replaced with an "HO" (hydrogen + oxygen) at the third position:


3bHSD is present all over the body (as is 5a-R, for the most part), but is found in especially high concentrations in the scalp and prostate, and it’s even possible that its actions on DHT will exacerbate male pattern baldness in the former tissue. Also, it’s worth noting that DHT is the androgen responsible for development of external genitalia. This is most likely the reason that women experience a temporary clitoral hypertrophy when they use the often recommended steroids (Primobolan, Anavar, Winstrol, etc…) in excessive doses.

In an interesting aside, I find it really interesting that the most typical steroids recommended are the most likely to cause clitoral enlargement and other possible androgenic effects. But on the bright side, in my experience with female athletes, that first effect is most welcome...actually, topical DHT can even be used to treat Microphalia (extremely tiny genitalia) in males (5). This last fact, if you’ve ever wondered, is the type of information discussed behind closed doors by of owners and staff of "private/invite-only" anabolic steroid boards and forums…for obvious reasons…

Ok, so now you know what DHT is, where it comes from, what it can do, and why it’s not a particularly potent anabolic when used alone. Here’s what Masteron is, relative to its parent compound, DHT. Masteron is an injectable steroid that is simply the DHT molecule which has been altered to be 2alpha-Methyl-DHT…you can see this modification by comparing the DHT molecule above with the following Masteron one, and paying special attention to the left hand side again, and the "H3C" modification:

Masteron, aka Drostanolone Propionate

This 2-alpha-methyl alteration makes it much more potent anabolic, although it’s still only about 60% as anabolic as testosterone and a quarter as androgenic. I’m going to speculate that these ratings make it not the most potent anabolic in the world, but its anti estrogenic effects plus its ability to increase aggression make it a very nice pre-contest addition. This is also where we get the absurd rumor that Masteron won’t do anything for you unless you’re already at a very low body-fat percentage. This is not true at all. No matter what body-fat percentage you’re at going to get a nice anti-estrogenic effect from Masteron, as well as some nice aggression and strength in the gym - the former and latter are both known as "non-genomic" effects, and are a result of the strong Central Nervous System stimulatory effects of Masteron, which is very common with DHT derived steroids. Basically, if you’re fat, and you take something that increases aggression and has anti-estrogenic effects (Halotestin and Arimidex, lets say), you wouldn’t expect to get huge and ripped. It’s the same thing with Masteron. Now, what if you add in Arimidex and Halotestin to a pre-contest cycle, you’ll get harder and look better. That’s exactly what’ll happen if you add Masteron into a Pre-contest cycle. It’s not that you have to be at some random body-fat percentage to get results from it, but you’ll need to be at that lower body-fat percentage to "see" those results. Again, if you’re fat and take Halo and Arimidex, you aren’t going to look much better…think of Masteron in similar terms, but it won’t work as well for aggression as Halotestin, and won’t be as good for combating estrogen as Arimidex. Gauged against either one of them alone, Masteron will likely make you look much harder and lift more weight. But if you are looking to do a low dosage cycle with a minimal amount of compounds in it, a simple Testosterone (propionate) and Masteron cycle may be exactly what you are looking for. On a personal note, that is a cycle that I use very frequently, at about 100mgs of each, shot every other day.

But has Masteron actually lived up to my claims for being an anti-estrogen? Yes. From 1968 to 1972, a decent sized study was conducted on Masteron, in a group of premenopausal women with breast cancer. About a third responded well to Masteron (6). This is because of its anti-estrogenic effects, clearly- though it doesn’t perform as well as Arimidex, Letrozole, or Aromasin. If you’re not running huge amounts of aromatizable steroids, this is a very good choice to add into your cycle. If you’re doing large amounts of those compounds, then you need to use a traditional anti-estrogen as your ancillary compound of choice. But if you’re running well under a gram of aromatizable steroids, Masteron will likely be all the anti-estrogen you need. This number comes from my person experience, as well as others I’ve interviewed. 

Now, as a bit of an addendum, I’d like to address the use of Masteron in women. Lets get this straight: Masteron was developed for women. Okay? Got me? If you’ ve been paying attention up to this point, you already know that Masteron is intended for females and is derived from the same root (DHT) as most other steroids commonly used and recommended for female athletes (Primobolan, Anavar, Winstrol, etc…are all derived from DHT). And, another shocking fact is that Masteron has a lower androgenic rating than almost every other commonly recommended steroid used by female athletes. Anavar has a rating of 24 compared to oral testosterone and Masteron has a rating of 25 compared to testosterone, expressed as a percent (so yes that means 24% and 25% respectively). 

Basically, Masteron works as a hormonal therapy for breast cancer and has been shown to be a useful and safe agent for females of all age groups, even though it may appear to be less effective then other possible therapies in postmenopausal patients (6). It is, therefore, very safe for women. Masteron is certainly no less safe than Anavar or Primobolan for women, as long as it’s used with something resembling a degree of respect and intelligence. 

My recommendations for female use of this compound would be to start between 10-25mgs every third day, and increase dosages from there if no side effects are experienced. At those dosages, I suspect no side effects would be experienced, and I’d be comfortable saying none will be experienced up through 20mgs, injected every other day. 

So there you have it. A totally new way to look at an old friend - Masteron - it’s useful as an anti-estrogen as well as an anabolic, and can certainly be safely used by both Men as well as women.


About The Author

Anthony Roberts has been researching anabolic steroids for over a decade and is the author of the new book, Anabolic Steroids: Ultimate Research Guide. He began his research at the age of seventeen while he was a competitive martial artist, ultimately winning a silver medal in his state martial arts tournament in the black belt division. His firsthand experience in steroids began after he switched sports and began playing rugby, in which he ultimately made two consecutive appearances at the hooker position in the national collegiate all-star games.