Ivermectin has been used orally and parenterally for the treatment of parasitic infections since the 1980s. A topical formulation is now available for the treatment of the chronic inflammatory skin condition, papulopustular rosacea.

The mechanism of action of ivermectin in the treatment of rosacea is not well understood. While ivermectin is thought to have some anti-inflammatory properties, its antiparasitic activity may also be important. Parasitic Demodex mites have been implicated in the pathogenesis of rosacea. Although Demodex mites are considered a normal part of the skin fauna, their mean density has been demonstrated to be 5.7 times higher for people suffering from rosacea compared to healthy controls. Upon histologic examination, spongiosis and lymphocytic infiltrates are often observed in areas surrounding follicles infested with Demodex mites, providing further evidence of their involvement in skin diseases.

During a 16-week trial, daily applications of ivermectin demonstrated an 83.0% reduction in inflammatory lesion counts, compared to 73.7% for twice-daily applications of metronidazole. Side effects of topical ivermectin are usually mild to moderate and transient in nature. Skin irritation, pruritus, and dry skin have been reported in less than 1% of trial participants.

References:

  1. Casas C, Paul C, Lahfa M, Livideanu B, Lejeune O, Alvarez-Georges S, et al. Quantification of Demodex folliculorum by PCR in rosacea and its relationship to skin innate immune activation. Exp Dermatol. 2012; 21: 906-10.
  2. Elston CA, Elston DM. Demodex mites. Clin Dermatol. 2014; 32: 739-43.
  3. Soolantra® (ivermectin) Australian approved product information. Belrose: Galderma Australia Pty Ltd. Approved September 2015.

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