Poor Oral Formestane Bioavailability - Myth?
- 08-05-2011, 10:23 PM
Poor Oral Formestane Bioavailability - Myth?
Why is it that people think oral formestane has such poor bioavailability. The below reference  finds that in women there is no difference in serum estradiol levels between a 250mg dose and a 500mg dose. Estrone was suppressed by all doses.
It should be noted that men likely require about a 15% higher dose simply because we metabolize (glucoronidation) formestane to a higher degree [2-3].
Is there research I am missing? If not, why mess with transdermals? Especially if you come in contact with women.
Eur J Cancer. 1992;28(2-3):415-20.
An endocrine and pharmacokinetic study of four oral doses of formestane in postmenopausal breast cancer patients.
Dowsett M, Mehta A, King N, Smith IE, Powles TJ, Stein RC, Coombes RC.
Department of Academic Biochemistry, Royal Marsden Hospital, London, U.K.
43 postmenopausal breast cancer patients were treated orally with the aromatase inhibitor formestane (4-hydroxyandrostenedione) at daily doses of 62.5, 125, 250 or 500 mg for 4 weeks followed by 250 mg daily for a further 4 weeks. For some patients, 62.5 mg did not suppress serum oestradiol levels maximally. The doses of 250 and 500 mg did not differ in their effectiveness. Oestrone levels were suppressed by all doses of formestane but no consistent changes of aldosterone, cortisol or 17-hydroxyprogesterone occurred. Serum levels of sex hormone binding globulin fell by about 15% during treatment with 250 mg formestane reflecting its minor androgenic activity. The maximum concentration and area under the curve of serum formestane levels after the first dose varied in an approximately linear manner with dose. It is concluded that formestane is an effective, specific suppressant of oestradiol levels via the oral route requiring no more than 250 mg to be given daily.
PMID: 1591054 [PubMed - indexed for MEDLINE]
Dowsett M, Cunningham DC, Stein RC, Evans S, Dehennin L,
Hedley A, Coombes RC. Dose-related endocrine effects and
pharmacokinetics of oral and intramuscular
4-hydroxyandrostenedione in postmenopausal breast
cancer patients. Cancer Res 1989;49(5):1306–12.
Dowsett M, Lloyd P. Comparison of the pharmacokinetics
and pharmacodynamics of unformulated and formulated
4-hydroxyandrostenedione taken orally by healthy men.
Cancer Chemother Pharmacol 1990;27(1):67–71.
- 08-05-2011, 11:24 PM
Check some of Dinoii's posts at LB and I think you will find data showing quite the opposite
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08-05-2011, 11:35 PM
08-08-2011, 04:13 PM
08-08-2011, 07:47 PM
08-08-2011, 09:31 PM
Would love to see anything you have that says otherwise.
08-08-2011, 10:18 PM
08-08-2011, 10:27 PM
08-08-2011, 10:33 PM
08-10-2011, 12:09 PM
08-10-2011, 12:24 PM
08-10-2011, 01:56 PM
From the top of my head I've read that the 3b enzyme converts 4OHA to 4OHT.
Maybe someone is getting more 4OHT conversion through TD which might be mislabeled as better "anti-estrogenic" effects?
08-10-2011, 03:12 PM
Even so the liver is more abundant with 17b-hsd (and gut) than the skin.
Problem with hitting the intestines and liver is still phase 1 and 2 drug metabolizing enzymes.
Still 250 mgs isn't an unreachable dose orally.
08-10-2011, 03:13 PM
08-10-2011, 03:43 PM
08-10-2011, 03:56 PM
Pp's self emulsifying drug delivery system is probably better than just downing some powder. It likely increases lymphatic absorption anywhere from 1-10% which should equal a significantly higher biological response.
Formex was probably even better at that mg for mg.
I may have some stuff sent in to test it out with bloodwork (estrone and estradiol).
08-10-2011, 03:58 PM
hmm, something to think about. i've never used it orally, if i was going to go with an oral, i'd pick 6-bromo.
I like transdermals though, better or not, well, that is yet to be seen. I think it can be more convient to apply a t/d and let it slowly be absorbed into the system vs getting it all at once.
what is the half life of formestane?
08-10-2011, 04:13 PM
why was formestane even DC'd?
"The only good is knowledge and the only evil is ignorance." - Socrates
08-10-2011, 04:35 PM
08-10-2011, 04:36 PM
08-10-2011, 04:38 PM
08-10-2011, 06:44 PM
08-10-2011, 08:10 PM
08-12-2011, 12:23 AM
Because you need 250mg-500mg per day vs 500mg form acetate injection once every 2 weeks
So i guess the assumption was injection was better so we need to rub it on our skin since we cant inject supplements.
Oral formestane works, if you take enough. I have never seen a supplement supply enough
08-12-2011, 11:06 AM
I thought Formex was a good idea. Some of the lymphatic prodrug research with the MCPE ester is fairly promising. I don't think I ever saw any bloodwork on the stuff though.
08-12-2011, 11:28 AM
Didn't Formex have a higher conversion rate to 4-hydroxy testosterone, and ended up being pretty suppressive? I recall the rumors, but never saw the "proof". The fact that it was D/C'ed makes me wonder though...
08-12-2011, 11:56 AM
Meaning a 50 mg Formex dose had a similar biological response as maybe 500mg or a gram of unesterfied formestane. Although that would contradict what dinoiii said about his in house tests (even a gram per day was not suppressive).
It may be possible 50mg of Formex resulted in a biological response greater than even a gram of formestane. It's impossible to know without oral pharmacokinetic research on Formex.
08-14-2011, 12:55 PM
08-14-2011, 01:41 PM
10-18-2011, 03:52 PM
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