Cyclofenil is the least popular of the three Selective Estrogen Receptor Modulators (SERM) being used in athletics today. I actually used this stuff about half a decade ago, when it was just as easy to get as Clomid, and a bit cheaper. As we already know, SERMs cause ovulation in women and (more importantly to us) increase testosterone and other beneficial hormones. This drug actually works by simulating the effects of testosterone via inhibiting the negative feedback loop caused by estrogen, with regards to testosterone production. This in turn causes the increased secretion of Gonadotropin Releasing hormone, which increases output of Luteinizing Hormone which (finally!) increases secretion of testosterone from your testes.
So what we have here is a compound which, being a SERM, will prevent gyno by binding to the estrogen receptor in breast tissue and thus preventing stronger estrogens from binding to those tissues. This should be familiar territory if you remember your facts on Clomid and Nolvadex.
The results indicate that cyclofenil, paradoxically, has two opposing actions on the hypothalamic-hypophyseal axis, one of them is estrogen-like, in that it depresses serum FSH levels and competitively binds to breast tissue (this is good, remember), and the other action is antiestrogen-like, in that it depresses serum PRL levels and raises LH levels (4). Overproduction of prolactin, as you recall will suppress Testosterone, and could induce lactation (gross!) in male breast tissue.
From the reading Ive done on this compound, I think 400-600mgs/day would be an appropriate dose for use in Post-Cycle-Therapy, or during a cycle (4). Dan Duchaine estimated roughly the same, saying that twice as much is necessary when compared to Clomid, twice as often. Due to its relative expense and unavailability when compared to other SERMs, such as Nolvadex and Clomid, I cant see this stuff making its way into many peoples ancillary regimen.