Eflornithine

Eflornithine irreversibly inhibits ornithine decarboxylase, an enzyme involved in the production of the hair shaft by the hair follicle. Eflornithine has been shown to reduce the rate of hair growth.

Steady state cutaneous penetration of eflornithine on facial skin of shaving women was 0.8%.

The steady state plasma half-life of eflornithine was approximately 8 hours. Steady state was reached within four days. The steady state peak and trough plasma concentrations of eflornithine were approximately 10 ng/ml and 5 ng/ml, respectively. The steady state 12-hour area under the plasma concentration versus time curve was 92.5 ng.hr/ml.

Eflornithine is not known to be metabolised and is eliminated primarily in the urine.

Non-clinical data reveal no special hazard for humans based on conventional studies of repeat dose toxicity, genotoxicity and carcinogenic potential, including one photocarcinogenicity study in mice. In a dermal fertility study in rats, no adverse effects on fertility were observed at up to 180 times the human dose. In dermal teratology studies, no teratogenic effects were observed in rats and rabbits at doses up to 180 and 36 times the human dose, respectively. Higher doses resulted in maternal and foetal toxicity without evidence of teratogenicity.