Mechanism of action
While warfarin is one of several drugs popularly referred to as a "blood thinner", this is a misnomer, since it does not affect the viscosity of blood.Warfarin inhibits the vitamin K-dependent synthesis of biologically active forms of the clotting factors II, VII, IX and X, as well as the regulatory factors protein C, protein S, and protein Z. Other proteins not involved in blood clotting, such as osteocalcin, or matrix Gla protein, may also be affected. The precursors of these factors require gamma carboxylation of their glutamic acid residues to allow the coagulation factors to bind to phospholipid surfaces inside blood vessels, on the vascular endothelium. The enzyme that carries out the carboxylation of glutamic acid is gamma-glutamyl carboxylase. The carboxylation reaction proceeds only if the carboxylase enzyme is able to convert a reduced form of vitamin K (vitamin K hydroquinone) to vitamin K epoxide at the same time. The vitamin K epoxide is, in turn, recycled back to vitamin K and vitamin K hydroquinone by another enzyme, the vitamin K epoxide reductase (VKOR). Warfarin inhibits VKOR (specifically the VKORC1 subunit), thereby diminishing available vitamin K and vitamin K hydroquinone in the tissues, which decreases the carboxylation activity of the glutamyl carboxylase. When this occurs, the coagulation factors are no longer carboxylated at certain glutamic acid residues, and are incapable of binding to the endothelial surface of blood vessels, and are thus biologically inactive.
As an alternative to the GnRH antagonist, also a GnRH agonist could be given, but agonist have to be started earlier to overcome the agonistic effect. Cetrorelix can be mixed with follitropin alpha without compromising their reported safety and efficacy. Contraindications
The use of cetrorelix is contraindicated in severe renal impairment. It is not intended for women aged 65 years or older. Use in women with severe allergic conditions is not recommended. Use with caution in women with active allergies or history of allergies. Research
Cetrorelix was under development for the treatment of benign prostatic hyperplasia, premenopausal breast cancer, endometriosis, ovarian cancer, prostate cancer, and uterine fibroids, but development for these indications was discontinued.A study published in Nature Medicine found a link between hormonal imbalance in the womb and Polycystic ovary syndrome (PCOS), specifically prenatal exposure to anti-Müllerian hormone. For the study, the researchers injected pregnant mice with AMH so that they had a higher than normal concentration of the hormone. Indeed, they gave birth to daughters who later developed PCOS-like tendencies. These included problems with fertility, delayed puberty, and erratic ovulation. To reverse it, the researchers dosed the polycystic mice with cetrorelix, which made the symptoms to go away. These experiments should be confirmed in humans, but it could be the first step in understanding the relationship between the polycystic ovary and the anti-Müllerian hormone. In another study, over a period of 3 weeks, daily injections of cetrorelix were administered to 12 men in order to suppress testosterone levels.