title: Application site affects the pharmacokinetics of topical testosterone applied to the axilla compared with the inner arm.
abstract: OBJECTIVE
  This study compared the pharmacokinetics of a single dose of 1% testosterone solution after application to the inner arm or the axilla as application sites for transdermal testosterone therapy.
  
  
  METHODS
  Healthy, not pregnant, premenopausal women, 18 to 45 years of age with a body mass index of 20 to 28 kg/m(2) were enrolled into a single-center, open-label, randomized, 2-way crossover study. Serum total testosterone (TT), free testosterone (fT), and sex hormone binding globulin concentrations were measured. Pharmacokinetic parameters determined from serum TT and fT included area under the serum concentration versus time curve from time zero (pre-dose) until 72 hours post-dose (AUC0-72), Cmax, and Tmax. Descriptive statistics were performed on serum concentrations of TT and fT for each site. ANOVA was performed on AUC0-72 and Cmax.
  
  
  RESULTS
  A single-dose application of 1% testosterone solution to the inner arm and the axilla produced clear increases in TT and fT. Slower and lower increases in TT and fT were observed after treatment to the inner arm. Based on baseline-corrected AUC versus time curves, the bioavailability of 1% testosterone solution was increased 2-fold for the axilla compared with the inner arm.
  
  
  CONCLUSIONS
  The absorption of a 1% testosterone solution was significantly greater after application to the axilla than to the inner arm. Study number DDS16; Australian Therapeutic Goods Administration, CTN 2005/158.
authors: Women's Health Research Program, School of Public Health and Preventive Medicine, Monash University, The Alfred Centre, Melbourne, Victoria, Australia. Electronic address: susan.davis@monash.edu.
authors: Susan R
authors: SR
authors: Davis
authors: Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia.
authors: Allan M
authors: AM
authors: Evans
authors: Acrux DDS Pty Ltd., West Melbourne, Victoria, Australia.
authors: Andrew
authors: A
authors: Humberstone
mesh_terms: D000279:Administration, Cutaneous; D000293:Adolescent; D000328:Adult; D001132:Arm; D001315:Australia; D001365:Axilla; D001682:Biological Availability; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D013739:Testosterone / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D055815:Young Adult
chemical_list: D012738:Sex Hormone-Binding Globulin; D013739:Testosterone
keywords: axilla; hypogonadism; testosterone; transdermal therapy