Transdermal Fentanyl Usage in Working-age Patients Undergoing Cancer Treatment: Prescription Pattern Analysis Using Large Claims Data in Japan.

The number of working-age individuals undergoing cancer treatment has been increasing. In these patients, transdermal fentanyl is the preferred treatment. However, it is known to have (1) pharmacodynamic interactions with benzodiazepines and (2) fever-induced pharmacokinetic variations. The aim of this study is to clarify the frequency of co-administration of benzodiazepine and the predictors for fever among working-age patients with cancer using transdermal fentanyl. We used a large claims data source including over 3.6 million patients. Finally, 759 working-age patients aged 20 to 60 years undergoing cancer treatment, in whom transdermal fentanyl was initiated, were analyzed. The proportion of patients receiving co-administration of benzodiazepines with the first administration of transdermal fentanyl was 16.5% (n = 125). This increased to 39.3% (n = 298) within 30 days. Predictive factors for fever using patients' baseline characteristics were male sex, gastrointestinal cancer, hematological cancer, and renal disease. To provide adequate pharmacotherapy to working-age patients undergoing cancer treatment with transdermal fentanyl, medical staff should pay attention to (1) avoid adding benzodiazepines easily and (2) monitor patients having predictors for fever to avoid fentanyl-related adverse events.