What is the 5-alpha reductase inhibitor that is incorporated in the Xandrox® solutions?
A. Azelaic acid. Azelaic acid has been proven to be an inhibitor of Type 1 and Type 2, 5-alpha reductase in the human skin. Azelaic acid has also been demonstrated to ‘inhibit the synthesis of all of the hormones in the 17-hydroxy group’, resulting in decreasing the levels of DHT in the scalp when used topically. In a study reported in the British Journal of Dermatology (Stamatiadis. 1988;119: 627-632), inhibition of 5-alpha reductase is virtually complete (98%) at 3 mmol/l. The Xandrox® solutions and lotion contain eighty eight times the amount necessary for 98% inhibition of Type 1 and Type 2 5-alpha reductase in vitro. Both types of 5alpha-reductase are present in the human scalp with Type 1 being the predominant isoenzyme. Allowing for the usual 4 or 5% absorption into the dermis and epidermis upon topical application, the amount of azelaic acid at the level of the hair follicles is at least 3 times the amount required for virtually complete inhibition of DHT synthesis.
