title: Implications of off-label use: An example from the final results of an observational cohort study on Intrinsa® (testosterone patch).
abstract: BACKGROUND
  Off-label use is where a medicinal product is used for a medical purpose not in accordance with the authorised product information. Intrinsa® is a transdermal testosterone patch, which is indicated for use in hypoactive sexual desire disorder in bilaterally oophorectomised and hysterectomised women receiving concomitant estrogen therapy.
  
  
  OBJECTIVE
  To describe the utilization characteristics of patients prescribed testosterone patch (Intrinsa®) and to assess, where possible, if the product is being used according to the authorised product information.
  
  
  METHODS
  Patients identified from dispensed prescriptions issued by general practitioners for Intrinsa® between March 2007 and August 2010. Postal questionnaires were sent to general practitioners six months following the date of the first prescription for Intrinsa® for each patient, requesting information including patient demographics and drug utilization.
  
  
  METHODS
  Menopausal status and use of concomitant estrogen therapy.
  
  
  RESULTS
  The final cohort consisted of 3073 patients; the majority were females (3017, 98.2%). The most commonly reported indication was hypoactive sexual desire disorder in 2324 female patients (77.0%). Only 43.5% female patients (n = 1313) were reported to have been hysterectomised and bilaterally oophorectomised. For 1029 (34.1%) female patients there was no evidence that the patient was using concomitant estrogen therapy. Overall, only 643 patients (20.9%) in the cohort were being prescribed Intrinsa® according to the manufacturer's recommendations.
  
  
  CONCLUSIONS
  Evidence obtained solely from clinical trials might not be generalisable where off-label prescribing occurs in real-life, so evidence from post-marketing observational studies is important to provide complimentary data on a product's safety and effectiveness.
authors.affiliation: Drug Safety Research Unit, Bursledon Hall, Southampton, UK School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, UK Vicki.osborne@dsru.org.
authors.forename: Vicki
authors.initials: V
authors.lastname: Osborne
authors.affiliation: Drug Safety Research Unit, Bursledon Hall, Southampton, UK School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, UK.
authors.forename: Deborah
authors.initials: D
authors.lastname: Layton
authors.affiliation: Drug Safety Research Unit, Bursledon Hall, Southampton, UK School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, UK.
authors.forename: Saad Aw
authors.initials: SA
authors.lastname: Shakir
keywords: Cohort study; drug utilization; off-label use; testosterone patch