Thread: Arimidex, aromasin, letro = all same potency in males?

I don't know for sure the facts but I can tell you this. I got gyno while on adex, got on letro within a few days gone. Same thing happened again same cycle, and letro is knocking it out yet again.

Femara (AKA Letrozole), is more effective than Arimidex in it's ability to pass thru the cell membrane of lipid (fat) cells and inhibit the activity of aromatase -- Arimidex is just over 80% effective at inhibiting aromatase, Femara is around 95-97% Levels of estrogen are totally undetectable in any patients taking Letrozole, and it has even been used to increase testosterone to normal levels (from sub-normal ones) and increase LH, FSH and SHBG (Epilepsy Behav. 2004 Apr;5(2):260-3). Other than that, both of these drugs stop the process of aromatization, rather than just blocking (competing for, if you prefer) the receptors as Clomid and Nolvadex do. An effective dose of Letrozole is 1-2.5 mg/day (I use 1mg/day), but be forewarned, it can kill your sex drive, and could decrease IGF levels. On the other hand, I've seen studies where it increases IGF levels. Also worth noting is that there's a rebound effect when you come off Letrozol. What can I say? Letrozole's effects on serum lipids (cholesterol, both HDL and LDL) are, in the words of one researcher: "inconsistent. "And compared with Aromasin and Arimidex, In non-cellular systems, letrozole is 2-5 times more potent than anastrozole and exemestane in its inhibition of the aromatase enzyme and activity, and in cellular systems it is 10-20x more potent! Letrozole (2.5mg daily) also achieved a much greater suppression of the plasma concentrations of both estrone and estrone sulphate (estrogens) than anastrozole (1mg daily) and a greater inhibition of in vivo aromatization also (sorry for the geek-speak.it's over for now.). ( J Steroid Biochem Mol Biol. 2003 Oct;87(1):35-45.) Exemestane can also cause androgenic sides (Clin Cancer Res. 2003 Jan;9(1 Pt 2):468S-72S.)(1. J Clin Endocrinol Metab 2000 Jul;85(7):2370-7 2. J Steroid Biochem Mol Biol 1997 Nov-Dec;63(4-6):261-7). I've used Letrozole, and it cleared up my minor gyno lumps, to the point that they are totally gone now.

How about Aromasin?

Well, its totally different than everything else we've looked at so far. Aromasin (exemestane) it is a aromatase inactivator (AI)...It actually makes estrogen receptors useless. Instead of just inhibiting production (as an anti-aromatase would do) it cuts off production totally. Aromasin can effectively prevent about 90-95% of estrogen conversion. Oddly, this compound can actually increase IGF levels (Anticancer Res. 2003 Jul-Aug;23(4):3485-91).Worth noting is that Aromasin may possibly be less harsh on blood lipids (having no effect: J Clin Endocrinol Metab. 2003 Dec;88(12):5951-6. ) than some of the other compounds mentioned here (with the exception of Nolvadex which may actually improve HDL & LDL in some cases: Br J Cancer. 2004 Aug 2;91(3):476-81.). Though it has also been shown to have an undesirable effect on blood lipids in some cases.
Lets talk about Arimadex (Anastrozole), now. From the research I've done, this seems to be one of the best ancillaries around and I'll tell you why. First off, 'dex is an aromatase inhibitor (AI.remember what that is?). 1mg per day of this stuff (J Clin Endocrinol Metab 2000 Jul;85(7):2370-7, "Estrogen Suppression in Males") was shown to decrease estrogen by 50% and increase testosterone levels by 58%. LH and FSH also went up slightly. The test increase didn't happen at a dose of .5 per day, but estrogen suppression was the same. Anastrozole also raises IGF1 and shows a trend towards increasing IGF2 (J Steroid Biochem Mol Biol. 2002 Apr;80(4-5):411-8) BTW, literature provided by the original maker of Arimadex states that stable blood plasma concentrations of the compound are achieved after 7 consecutive 1mg daily doses. All of that plus the usual blood lipid changes we've seen with most of the anciliaries we've looked at! Anyway, that's a pretty hefty decrease in estrogen, even at .5mg/day.
For my money, if I wanna stop aromatization during a cycle, I'm gonna use Arimadex at .5mgs per day or Letrozole at 1mg/day. They are perfect during-cycle ancillaries. Unfortunately, you need to take Anastrozole for a week to get a steady level of it in your blood (same thing goes for Exemestane), wheras you need to take Letrozole for 60 days to get a steady blood plasma level. Though Anastrozole has a ½ life of 41-48 hours, and exemestane has a ½ life of 27 hours, Letrozole has a whopping 2-4 day (!) ½ life (Clin Cancer Res. 2003 Jan;9(1 Pt 2):468S-72S.).
What about HCG (Human Chorionic Gonadotropin)? For starters, it increases (stimulates) endogenous (natural) testosterone production. It's ideal for post-cycle. I've found personally that 500IU every other day or even every day, post-cycle works best for me. Incidentally, this is the PDR (and Dan Duchaine's) reccomendation. In one study I looked at, 6000IU of HCG elevated test levels for 6 days. That's why a lot of people recommend taking it every 3-5 days. I'd have more stable blood levels, though if I shot it more frequently .remember, it's non-estrified and a water-based injectable, after all. In that same study I read, 1500IU of HCG shot test levels up between 250 and 300%. Again, though, I'd be more comfortable with the more stable and slow increase. Also, keep in mind that HCG suppresses FSH and LH production and has been anecdotally linked to gyno. Thus, it (in combination with Nolvadex) is ideal for post-cycle recovery.when gyno is not as much of an issue (due to the nolvadex and the cessation of other compounds), but restoring natural test levels is.

SO.lets review:

During a cycle (because I ALWAYS use test in my cycles), I think it's a good idea to use Arimadex at .5-1mg per day, or Letrozole at 1-2.5mgs/day, to take care of aromatization, thus preventing side effects related to estrogen. If I'm using gear that has progesteronic side effects , I'm gonna avoid nolvadex, and I'm gonna have to throw in some Bromocriptine at 2.5-5mgs every day, especially when I'm using lots of Tren (and perhaps trying to get cut), because I'd want the added "side effects" we already discussed from the Bromo, and I'd thrown in that T3 as well. When I'm all done with the cycle, Nolvadex (at 10-20mgs/day for a month) post cycle, plus 500-1000 IU of HCG every other day (for 2-3 weeks) will help restore test levels to normal. Clomid at 50mgs per day will .umm..keep or return your nuts to a normal size, and will have anti-estrogenic and pro-gonadotropic effects. I used to like it during a cycle to keep my nuts big. Sorry, there's no really polite way to say that stuff about keeping your nuts normal.... But in any case, I'd run the Clomid for about 2 weeks of the start of PCT if this was a concern, or during the cycle...possibly for the last 2 weeks, if you want. I used to use it quite alot, myself, during a cycle (at 50-100mgs/day). Although I've been shying away from it recently due to the relative inexpensiveness of other, better compounds...and the fact that clomid messes with my vision.
So there it is. I hope this answers some questions for everyone and helps you to make decisions concerning ancillaries in your next cycle.

Addendum:

One thing you won't be using in your next cycle, however, it Falsodex. It's new to our little world of AAS users, and one injection per month can give you all the anti-estrogen and anti-progesterone effects you need!
Falsodex is an estrogen receptor antagonist, which has no agonist effects at all. What it does is downregulates Estrogen Receptors (kinda like how Clen DownRegulates your beta receptors....so you get decreased effects from the stuff). Basically, it binds to the Estrogen Receptor more strongly then Tamoxifen, but still has no estrogen agonist effects. Here's the interesting part:
The resultant downregulation of your Estrogen Receptors from the use of Falsodex results in decreased _expression of the Progesterone Receptor as well! Tamoxifen, as we all know, can increase the sides from progesteronic drugs because of an increase in progesterone receptor _expression. So you can take this stuff as both an anti-estrogen and an anti-progestin! No more buying Arimidex or whatever, and Bromocriptine! Sweet, huh?

^ thanks for that article. But i think he's still basing those numbers off of researches done on females.

there was a website that had some nice studies and numbers on the power of each of the top ai's and femara was at the top of the list.I wish I had saved the link.femara is your best bet for fighting gyno but it does kill your sex drive as its very powerful.

I think the potency was compared in female studies.

But, as heavyiron mentioned, perhaps the potency doesn't vary much in males?

Female studies have little application to males when it comes to E2 suppression. Our circulating T levels make AI's less effective AND shorten their half lives compared to females. The following excerpt from a human trial in men administered Aromasin comments on this;

The maximal suppression evoked by exemestane at the single dose of 25 mg in the present study was similar to published results in postmenopausal women, but the time course differed (24). Evans et al. (24) reported that a single 25-mg oral dose of exemestane maximally suppressed estradiol concentrations by 72% 3 d after administration, and estradiol levels returned to baseline only 8–11 d after drug administration. In the present study maximal suppression of estradiol of 62% was observed 12 h after exemestane administration and returned to baseline 3–6 d after administration. The reason for this difference is not clear, but may be related to the shorter half-life of exemestane in males, the lower exposure to exemestane, and the higher levels of the aromatase substrates androstenedione (1 ng/ml in young males vs. 0.5 ng/ml in postmenopausal women), particularly the much higher testosterone concentrations in young males than in postmenopausal women (700 ng/dl vs. 20 ng/dl, respectively) (25). This is supported by the observation that in the 10-d study in young males reported here, the suppression of estradiol is weaker (due to the very high levels of the precursor testosterone) than that of estrone (due to androstenedione levels not very different from those in postmenopausal women). A limited suppression of circulating estradiol (50%) has been reported in a similar study in young males treated with 1 mg daily anastrozole (7), a dose that reduces estradiol by 85% in postmenopausal women (23).

This shows 2.5mg daily Letro lowers E2 about 46% in younger men. These men had higher T levels so that is probably why suppression was less then the older guys. If you are using Testosterone then it looks like Letro lowers E2 less than Adex or Aromasin by a few percent.


J Clin Endocrinol Metab. 2005 Oct;90(10):5717-22. Epub 2005 Jul 26.

Comparative assessment in young and elderly men of the gonadotropin response to aromatase inhibition.

T'Sjoen GG, Giagulli VA, Delva H, Crabbe P, De Bacquer D, Kaufman JM.
Department of Endocrinology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium. guy.tsjoen@ugent.be

Abstract

CONTEXT: Aging in men is associated with a decline in serum testosterone (T) levels.
OBJECTIVE: Our objective was to assess whether decreased T in aging might result from increased estradiol (E2) negative feedback on gonadotropin secretion.
DESIGN AND SETTING: We conducted a comparative intervention study (2004) in the Outpatient Endocrinology Clinic, Ghent University Hospital.
PARTICIPANTS: Participants included healthy young and elderly men (n = 10 vs. 10).
INTERVENTIONS: We used placebo and letrozole (2.5 mg/d) for 28 d, separated by 2 wk washout.
MAIN OUTCOME MEASURES: We assessed changes in serum levels of free E2, LH, and FSH, free T, SHBG, and gonadotropins response to an i.v. 2.5-microg GnRH bolus.
RESULTS: As assessed after 28 d of treatment, letrozole lowered E2 by 46% in the young men (P = 0.002) and 62% in the elderly men (P < 0.001). In both age groups, letrozole, but not placebo, significantly increased LH levels (339 and 323% in the young and the elderly, respectively) and T (146 and 99%, respectively) (P value of young vs. elderly was not significant). Under letrozole, peak LH response to GnRH was 152 and 52% increase from baseline in young and older men, respectively (P = 0.01).
CONCLUSIONS: Aromatase inhibition markedly increased basal LH and T levels and the LH response to GnRH in both young and elderly men. The observation of similar to greater LH responses in the young compared with the elderly does not support the hypothesis that increased restraining of LH secretion by endogenous estrogens is instrumental in age-related decline of Leydig cell function.


PMID: 16046582 [PubMed - indexed for MEDLINE]

Thanks for that heavyiron!

So, according to that study, letro could be even slightly weaker than aromasin and arimidex in males?

Originally Posted by minimal

Thanks for that heavyiron!

So, according to that study, letro could be even slightly weaker than aromasin and arimidex in males?

Yeah, but its splitting hairs. Since higher T levels make AI's less effective and shorten their half lives suppression may move around a bit depending how much T you are on. In other words, only labs are going to tell you E2 levels and therefore suppression.

Originally Posted by heavyiron

Yeah, but its splitting hairs. Since higher T levels make AI's less effective and shorten their half lives suppression may move around a bit depending how much T you are on. In other words, only labs are going to tell you E2 levels and therefore suppression.

this is interesting considering all the anecdotal evidence of letro crushing e2 and resolving gyno when adex and aromasin aren't working.

Some anecdotal info here, When on 300 mg test a week and 0.8 mg of letro every 3 days my E2 is about 20 pg/ml, which is in normal range. Test is about 3x mid-range normal ~2100 ng/dl.

Originally Posted by Glycomann

Some anecdotal info here, When on 300 mg test a week and 0.8 mg of letro every 3 days my E2 is about 20 pg/ml, which is in normal range. Test is about 3x mid-range normal ~2100 ng/dl.

Wow, that's awesome, and cheap. Do you know when your bloodcwascdrawn in relation to dose. Do you stay in 20's for 3 days?

Originally Posted by exphysiologist88

this is interesting considering all the anecdotal evidence of letro crushing e2 and resolving gyno when adex and aromasin aren't working.

Aromasin will definately work to resolve gyno. 25mg every 12 hours.

Originally Posted by heavyiron

Aromasin will definately work to resolve gyno. 25mg every 12 hours.

Well, I definitely respect your knowledge. Aromasin definitely prevented any gyno during my cycle.

some intelligent post in this thread, niiicceee

I agree great info here

Originally Posted by heavyiron

Aromasin will definately work to resolve gyno. 25mg every 12 hours.

Would you suggest letro when running T @ 1000+Wk? Im almost scared to use anything other now. even at much lower weekly T doses, im paranoid

Originally Posted by SFW

Would you suggest letro when running T @ 1000+Wk? Im almost scared to use anything other now. even at much lower weekly T doses, im paranoid

damn, I'm scared to run more than 500mg/week because of gyno.

Originally Posted by exphysiologist88

damn, I'm scared to run more than 500mg/week because of gyno.

Couldn't higher dose of AI solve this issue?

Originally Posted by minimal

Couldn't higher dose of AI solve this issue?

I'm sure it could, but I'm a paranoid fucker, especially when it comes to gyno, and it seems relatively safe and effective to run about 500 mg of test and just add something else that doesn't have much sides (EQ, Mast, Primo). I'm new to this too, so that makes a difference.

Originally Posted by SFW

Would you suggest letro when running T @ 1000+Wk? Im almost scared to use anything other now. even at much lower weekly T doses, im paranoid

Yup, there is some evidence E2 receptors reach saturation at 600mg weekly of T so if you have E2 problems at 600mg they will likely be the same at 1 gram.

I prefer Aromasin since there is little to no Estro rebound when you stop using it but Letro is fine.

I have also preference for aromasin because it has less sides and It is a very potent estrogen binder and IMO is really necessary on higher dose cycles.

when u use letro I would watch would HDL cholesterol, as this might shift in the negative as estrogen levels are suppressed. this is a main problem when u use anastrozole or femara these 2 anti e's work is they inhibit the aromatase enzyme. by inhibiting the enzyme which converts testosterone to estrogen, you reduce or even come close to eliminating estrogen production.

aromasin/exemestane it works differently. it does not stop the body from producing estrogen. rather, it makes it so the estrogen is unable to bind to receptors by deactivating the binding enzyme. if the estrogen cannot bind, you simply will not get bloated or get gyno. the estrogen is crippled due to exemestane. however, since the estrogen is still floating around, it will not negatively affect your lipid/cholesterol profile.

Letro is the only AI i have used that gave me friggin hot flashes lol