
Originally Posted by
Big
off topic for a moment guys, bear with me:
selective estrogen receptor modulators(SERMs) such as Clomiphine and Tamoxifen are selective to which tissues they bind too. Clomid being selective to the suprapituitary, while Tamox is selective to breast, bone, and liver ERs. I've come to this conclusion based on the comparison of studies on both SERMs. In every study showing benefit to HPTA from tamoxifin, the duration of the administration is 3-12months(This includes studies cited by William Llewellyn in his Nolva vs Clomid article). In studies showing levels of LH, FSH, and Testosterone checked after short durations of tamox, they were either insignificant, or their was an actual drop. I believe this is because tamox selectively works at the mammery(as well as bone and liver), thus taking longer for LH stimulation to occur.
With clomid, benefit to gonadotrophin concentrations, LH, FSH, and serum testosterone can be seen in short periods of 2-6wks. Because of the apparent selective nature of the two, and given our usual PCT duration, clomid is by far superior at LH stimulation than Nolva. Now both is the wise choice for a couple of reasons:
1. Nolva acts as the preventive measure to the estrogen flux
occured PC while clomid is the primary LH stimulator(Even more so in the case an AI is not used).
2. If your running a longer PCT, clomid needs to be discontinued after a while as it has been shown to desensitize GnRH, this due, IMO, to it's selective nature to the suprapituitary. In the longer forms of PCT, the clomid will be phased out, leaving Nolva and L-dex
credit: Pheedno
NOTE: Clomid and Nolvadex are both anti-estrogens belonging to the same group of triphenylethylene compounds. They are structurally related and specifically classified as selective estrogen receptor modulators (SERMs) with mixed agonistic and antagonistic properties. This means that in certain tissues they can block the effects of estrogen, by altering the binding capacity of the receptor, while in others they can act as actual estrogens, activating the receptor. In men, both of these drugs act as anti-estrogens in their capacity to oppose the negative feedback of estrogens on the hypothalamus and stimulate the heightened release of GnRH (Gonadotropin Releasing Hormone). LH output by the pituitary will be increased as a result, which in turn can increase the level of testosterone by the testes.
Although these two are related anti-estrogens, they appear to act very differently at different sites of action. Nolvadex seems to be strongly anti-estrogenic at both the hypothalamus and pituitary, which is in contrast to Clomid, which although a strong anti-estrogen at the hypothalamus, seems to exhibit weak estrogenic activity at the pituitary.
credit: Llewellyn