Drug utilization of Intrinsa (testosterone patch) in England: interim analysis of a prescription-event monitoring study to support risk management.

BACKGROUND: Intrinsa is a transdermal testosterone patch that is indicated for use in hypoactive sexual desire disorder (HSDD) in women who have undergone bilateral oophorectomy and hysterectomy (surgically-induced menopause) receiving concomitant oestrogen therapy.
OBJECTIVE: To describe the utilization characteristics of the patients prescribed testosterone patch (Intrinsa) based on an interim analysis of an ongoing Prescription-Event Monitoring study in England, and to assess, where possible, if the product is being used within the licensed therapeutic indication.
METHODS: In this interim analysis, patients were identified from dispensed prescriptions that had been issued by general practitioners (GPs) for Intrinsa from March 2007. 'Green form' questionnaires were sent to GPs 6 months following the date of the first prescription for Intrinsa for each individual patient, requesting information including age, sex, start and stop dates of treatment (if stopped), prescribing indication and reasons for stopping. Additional questions were asked regarding the patient's menopausal status and use of concomitant oestrogen therapy.
RESULTS: The interim cohort consisted of 756 patients. The majority of patients were reported to be female (746 [98.7%]) with a median (interquartile range) age of 50 years (44-55 years). The most commonly reported indication was the licensed indication of HSDD in 580 patients (76.7%). Just under one-half of the patients (n = 364 [48.1%]) were reported to have been hysterectomized and bilaterally oophorectomized (surgically-induced menopause) prior to starting Intrinsa; 127 patients (16.8%) were naturally menopausal. For 222 patients (29.4%) the GP specified that the patient was not using concomitant oestrogen therapy. Overall, only 219 patients (29.0%) in the cohort were being prescribed Intrinsa according to the manufacturer's recommendations.
CONCLUSIONS: This study has highlighted that some clinicians are prescribing this product outside the recommended terms of the licence, with less than 30% of patients receiving Intrinsa according to prescribing guidelines. All events experienced by these patients will be analysed to detect any possible adverse events from using Intrinsa outside of the licensed therapeutic indication. The findings support the ongoing postmarketing risk management of the product.