Capryloyl glycine and soy isoflavonoids in hypertrichosis: An experimental and placebo‐controlled clinical study

BACKGROUND: The management of acquired hypertrichosis (HT) is based on the search of the causes and subsequent specific treatment. However, simultaneous hair removal is important. No single method for hair removal is appropriate for all patients and skin areas. Treatment options are actually limited and clinical results are often unsatisfactory. Ornithine decarboxylase 1 (ODC1), an enzyme present in hair follicles, is considered as a potential target to inhibit hair growth. Only eflornithine hydrochloride, an inhibitor of ODC1, showed to be partially effective in the management of acquired HT. AIMS: The aim of our study was to evaluate the potential inhibition of ODC1 activity by a cream containing 4% capryloyl glycine, an ODC1 inhibitor, and 1% glycine soy‐fermented extract (soy isoflavonoids). Furthermore, we present the results of a placebo‐controlled clinical study that evaluated the efficacy and tolerability of this cream. METHODS: The ODC1 activity was detected by measuring absorbance at 340 nm. In the presence of ODC1 inhibitors, absorbance decreases as a function of inhibition. Difluoromethylornithine (DFMO) was provided as an inhibitor control. ODC1 activity inhibition was expressed as percentage of control (untreated sample). All data were presented as mean ± standard deviation of three independent experiments. To determine if statistically significant differences between treatments were present, a t test analysis was performed. The differences between groups were considered significant at p < 0.05. Twelve Caucasian female adult patients, with HT located on the forearms, were enrolled. The study cream (product A) was applied twice/day for four months on the right forearm. A placebo cream (product B) was applied twice/day for four months on the left forearm. Clinical efficacy was evaluated by means of macrophotography. RESULTS: The cream significantly inhibited ODC1 activity (35.1 ± 0.5% inhibition, equivalent to a 64.9 ± 0.5% ODC1 activity). DFMO completely abolished the enzymatic activity (100 ± 5% inhibition, equivalent to 0 ± 5% ODC1 activity). All patients were considered evaluable. In 11 out of 12 patients (91.7%), who were treated with product A, an improvement was observed. No improvement was observed in patients treated with product B. The global assessment showed good efficacy in 7 patients (58.3%) and moderate efficacy in 5 patients (41.7%) treated with the product A. No efficacy was detected in patients treated with product B. CONCLUSIONS: The study cream showed to be effective in Caucasian, adult, female patients with hypertrichosis located on the forearms.