title: Effects of skin washing on systemic absorption of testosterone in hypogonadal males after administration of 1.62% testosterone gel.
abstract: OBJECTIVE
  The impact of washing on the pharmacokinetics, systemic absorption and residual testosterone on the skin after application of a 1.62% testosterone gel was investigated in an open-label, randomized, three-way crossover study in hypogonadal men.
  
  
  METHODS
  Twenty-four hypogonadal men (total testosterone <300 ng/dL) applied 5 g of 1.62% gel (81 mg testosterone) once daily to the shoulders/upper arms for 7 days during each of three consecutive treatment periods. On the 7th dosing day of each period, the skin was washed (soap/water) at one of the following times: 2, 6, or 10 hours post-dose. Pharmacokinetic serum samples were collected at baseline, and on days 6 (no washing) and 7 (with washing) of each treatment period. Skin stripping for determination of residual testosterone was also performed on days 6 and 7. A single location on the application site was stripped a total of 10 times. Testosterone was extracted from the tape strips using ethanol, and concentrations were determined using high performance liquid chromatography with diode array detection (HPLC-UV).
  
  
  METHODS
  Testosterone C(max), AUC(0-24), average concentration over the dosing interval (C(av)), and safety were assessed.
  
  
  RESULTS
  Washing at 2 and 6 hours caused a 10-14% decrease in AUC(0-24) and C(av), but not C(max). Washing 10 hours after gel application had no effect on C(max), AUC(0-24), or C(av). Skin washing decreased the mean amount of testosterone remaining on the skin surface by at least 81%.
  
  
  CONCLUSIONS
  Washing the site of gel application as soon as 2 hours after application had little impact on bioavailability and was effective in reducing residual testosterone on the skin. This finding may be important to prevent secondary transfer.
  
  
  CONCLUSIONS
  The experimental conditions using uniform timing and procedures for dose administration and washing may not fully reflect real world circumstances. CLINICAL TRIAL REGISTRATION NCT NUMBERS: Study was not registered (first subject enrolled 22 December 2006).
authors.affiliation: Abbott, Abbott Park, IL 60064, USA.
authors.forename: Jodi
authors.initials: J
authors.lastname: Stahlman
authors.forename: Margaret
authors.initials: M
authors.lastname: Britto
authors.forename: Sherahe
authors.initials: S
authors.lastname: Fitzpatrick
authors.forename: Cecilia
authors.initials: C
authors.lastname: McWhirter
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Testino
authors.forename: John J
authors.initials: JJ
authors.lastname: Brennan
authors.forename: Troy L
authors.initials: TL
authors.lastname: Zumbrunnen
mesh_terms: D000279:Administration, Cutaneous; D000328:Adult; D000368:Aged; D001494:Baths; D018592:Cross-Over Studies; D005782:Gels / Q000008:administration & dosage / Q000627:therapeutic use; D020249:Hormone Replacement Therapy / Q000379:methods*; D006801:Humans; D007006:Hypogonadism / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D012867:Skin / Q000187:drug effects; D012869:Skin Absorption; D013739:Testosterone / Q000008:administration & dosage / Q000009:adverse effects* / Q000097:blood / Q000493:pharmacokinetics*
chemical_list: D005782:Gels; D013739:Testosterone