Pregnyl, manufactured by Merck, is the leading brand name of the drug Human Chorionic Gonadotropin (HCG) and is a highly purified pyrogen-free form of HCG. HCG acts like luteinizing hormone by stimulating production of gonadal steroid hormones which causes increased production of testosterone and, for women, to induce progesterone release in the ovaries. It is used primarily by females undergoing fertility treatment as well as by hypogonodal males seeking to kickstart their testes' ability to naturally secrete male hormones.
Off-Label - Related to the use of Pregnyl by hypogonadal males, HCG has become the drug of choice for many anabolic steroid users seeking to maintain normal testicular size while using steroids, or else to restore normal testes size and function at the end of a steroid cycle. These individuals will typically dose HCG at a lower dose than females undergoing fertility treatment and in a pulse-like dosing regimen which typically lasts for just 1-2 weeks since prolonged use of HCG can actually lead to inhibition of normal hormonal function.
For women who are struggling to conceive, HCG plays an important role by stimulating ovulation which is reliably triggered between 38 and 40hrs after a single injection. This allows for an attempt to then conceive either naturally or via artificial insemination. Males too will also sometimes be prescribed HCG during fertility treatment but more commonly when trying to correct hypogonadism.
Pregnyl is a very specialised drug which is reserved for use for specific conditions affecting both men and women.
Pregnyl use will depend on the reason for which it is taken, with doing regimens being significantly different both in terms of dose and frequency, depending on the reason for its administration.