title: Transdermal estradiol and testosterone transfer in man: existence, models, and strategies for prevention.
abstract: BACKGROUND
  Transdermal hormone application allows delivery of a clinically relevant hormone dose often with fewer systemic side effects than oral formulations. However, transdermal hormone transfer from a dosed individual to naïve interpersonal contact occurs and may cause significant hormone imbalance and adverse effects.
  
  
  METHODS
  We reviewed PubMed, Medline, and Scopus articles from the years 1950 to 2010 for articles related to transdermal hormone transfer in the setting of in vivo and in vitro human and animal models. We used the following key words: transfer, transdermal, absorption, cutaneous, hormone, estradiol, and testosterone. Unpublished trials were reviewed on the US Food and Drug Administration (FDA) website for product approval.
  
  
  RESULTS
  Data reflecting in vivo transfer of transdermal estradiol and testosterone in man is available from case reports, clinical trials, and FDA product information. While results clearly show that transfer can occur, methods for measuring the effect are not standardized and are thus difficult to compare among positive and negative studies. No in vitro human studies or animal models have been developed to specifically examine transfer potential of transdermal estradiol or testosterone.
  
  
  CONCLUSIONS
  It is necessary to consider the mechanism behind transdermal hormone transfer and consider ways to enhance clinical benefits to the dosed individual while minimizing transfer to a naïve interpersonal contact. A detailed discussion of trial comparisons and future optimization methods may help enhance our understanding of the potential for transdermal hormone transfer and encourage development of newer formulations and/or application methods to minimize its occurrence.
authors.affiliation: Department of Dermatology and Psoriasis Treatment Center, University of California San Francisco, San Francisco, CA 94143-0989, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Busse
authors.forename: H I
authors.initials: HI
authors.lastname: Maibach
mesh_terms: D000279:Administration, Cutaneous; D002626:Chemistry, Pharmaceutical; D004958:Estradiol / Q000008:administration & dosage / Q000009:adverse effects* / Q000378:metabolism; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D005260:Female; D020249:Hormone Replacement Therapy / Q000009:adverse effects*; D006801:Humans; D008297:Male; D018570:Risk Assessment; D012867:Skin / Q000378:metabolism*; D012869:Skin Absorption; D013739:Testosterone / Q000008:administration & dosage / Q000009:adverse effects* / Q000378:metabolism
chemical_list: D013739:Testosterone; D004958:Estradiol