Topical eflornithine (Vaniqa®) in hirsutism

• eflornithine is a specific, irreversible inhibitor of the enzyme ornithine decarboxylase present in hair follicles
  • ornithine decarboxylase enzyme is responsible for a key step in the biosynthesis of polyamines such as spermidine and putrescine
    • it is believed that these polyamines have important roles in cell proliferation, and blocking them in hair follicles slows the growth of the hair
    • there is a continual regeneration of ornithine decarboxylase. Therefore when inhibition of this enzyme ceases, the functional activity of ornithine decarboxylase increases (i.e. hair growth resumes)
  • topical eflornithine is applied twice daily to affected areas of the face
    • topical eflornithine was evaluated in 596 adult women in two multicenter, randomized, double-blind, placebo-controlled therapeutic trials (1)
      • the women recruited in the trial had five or more terminal hairs per square centimeter in four discrete facial areas 48 hours after shaving, as determined by video image analysis
      • all the women habitually removed facial hairs at least twice a week
      • eflornithine cream was applied twice daily for 24 weeks, followed by an 8-week no treatment period
        • after 24 weeks, 32% of patients treated with topical eflornithine were judged "clinical successes" vs. 8% of the placebo group
        • when "clinical success" and "improved" were taken together, the percentage of patients with a positive response to eflornithine at 24 weeks jumped to 58% versus 34% in the placebo group
        • self-assessment by patient questionnaire showed eflornithine to reduce overall discomfort and bother by 33% in the treated group vs. 15% in the placebo group
        • benefit of eflornithine to be lost after the 8-week no-treatment phase, when hair growth returned to its pretreatment rate
        • adverse effects
          • most common reported side effect was acne (approximately 20%); however, the rate of acne reported in the placebo group was virtually the same
          • about 15% of eflornithine group reported symptoms of burning/stinging/tingling and in only 5% of the placebo group, making this the most common side effect specific to eflornithine vs. the placebo
          • the adverse effects of eflornithine were generally mild in nature and no serious treatment-related events occurred
    • in the UK topical eflornithine is being marketed as a treatment to reduce the frequency of a woman's usual method of hair removal and not as a replacement for the current method

Reference:

1. Balfour JA, McClellan K.Topical eflornithine. Am J Clin Dermatol 2001; 2:197–201
2. The Practitioner 2005; 249: 398-407.