Menatetrenone (INN), also known as MK4, is a vitamin K compound used as a hemostatic agent, and also as adjunctive therapy for the pain of osteoporosis. Menatetrenone is one of the nine forms of vitamin K2.
MK4 is produced via conversion of vitamin K1 in the body, in the testes, pancreas and arterial walls. While major questions still surround the biochemical pathway for the transformation of vitamin K1 to MK4, studies demonstrate the conversion is not dependent on gut bacteria, occurring in germ-free rats and in parenterally-administered K1 in rats. In fact, tissues that accumulate high amounts of MK4 have a remarkable capacity to convert up to 90% of the available K1 into MK4.
MK4 is marketed for the osteoporosis indication in Japan by Eisai Co., under the trade name Glakay.