J. Soc. Cosmet. Chem. 24 523-536 (1973) ¸ 1973 Society of Cosmetic Chemists of Great Britain Male pattern baldness and the metabolism of androgens by human scalp skin K. D. BINGHAM and D. A. SHAW* Presented at the 7th Congress of the International Federation of Societies of Cosmetic Chemists, in Hamburg, Germany, 13th September 1972 Synopsis---Human male scalp skin was incubated with [4-x4C]TESTOSTERONE and the metabolites identified were 5a-androstane-3a, 1713-diol, androsterone, epiandrosterone, dihydro- testosterone, androstenedione, and androstanedione. A non-polar metabolite thought to be a steroid ester was also found. One bald and one hairy SCALP biopsy specimen from each of five subjects were incubated with [4-x4C]testosterone for 1 h and the amounts of each metabolite were measured after sepa- ration by thin-layer chromatography. Both the uptake and METABOLISM of testosterone were greater in bald skin than in hairy skin. The percentage of each metabolite in the total metabolite pool was found to be fairly constant thus demonstrating that male pattern BALDNESS was not accompanied by any gross change in the metabolism of testosterone. The main finding was that bald skin contained increased activity of 5a-reductase(s). Four of the metabolites of testosterone, namely dihydrotestosterone, androstenedione, androstanedione, and epiandrosterone were incubated with bald and hairy scalp skin and the metabolites identified. The results from these further studies showed that there was no gross change in the metabolism of these STEROIDS in male pattern baldness and also that the activity of 5ct-reductase(s) was greater in bald skin than in hairy skin from the same subject. INTRODUCTION Since the time of the ancient Egyptians, about 4 000 years ago (1), the scalp hair has been the subject of considerable attention by both cosmeticians and the medical profession. There are several different types of *Unilever' Research, Isleworth Laboratory, Middlesex, England. 523

524 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS baldness or alopecia but the one which is the subject of these studies is of the male pattern type. This type has been estimated to comprise more than 90•o of all cases of baldness. The term male pattern baldness has been given to this condition because of the characteristic way in which the hair is lost, usually starting with a recession in the fronto-temporal region. Countless numbers of alleged cures for baldness have been formulated ranging from the very old--such as a mixture of crocodile, lion, hippo- potamus, and serpent fat--to the very new--such as ultrasonics. However, none of these 'cures' has been successful and at the present time the only effective treatment is the auto-transplantation of small pieces of scalp skin from hairy to bald regions of the head. When the wound has healed the hair on the transplanted skin retains the characteristics of the donor site, i.e. it will continue to grow (2). However, the growth of hair can never spread beyond the boundary of the transplant. The reports that baldness can be arrested or new growth obtained with the male sex hormone testosterone (3), oestrogens (4), or anti-androgens (5) are difficult to substantiate. The use of such substances is often accompanied by undesirable side-effects because of their varied and potent biological activities. On the human scalp, as on the rest of the human body, the formation of hair by individual follicles is intermittent. Thus the growth of hair proceeds in cycles each consisting of an active growth period (anagen, 3-6 years on the scalp) and a resting period (telogen, 2-6 months on the scalp) when the hair is retained as a dead (club) hair in the inactive follicle. Anagen and telogen are separated by a transition phase called catagen which lasts for about 2 weeks. There is a good deal of evidence to show that the hair growth cycle in laboratory animals involves an inherent rhythm which can be slowly modified by systemic factors such as steroid hormones (6) and there seems to be no reason why this explanation should not also apply to human hair. During the balding process the period of anagen becomes progressively shorter while the periods of catagen and telogen do not change to any degree (7). This gradual reduction in the period of the growing phase causes a corresponding progressive reduction in the length of hair grown (and also thickness), an increase in the rate of hair fall, and a decrease in the density of hair on the head (7). Finally the pigmented terminal hairs are replaced by the very short unpigmented vellus hairs which cover the scalp of a bald man. Three factors control the onset and progress of male pattern baldness. These are age, heredity, and androgenic status normally all of these factors must operate to ensure that baldness will occur. Males under the age of puberty do not go bald, but after puberty the chances of doing so become