Prevalence and Patterns of Off-Label Transmucosal Immediate-Release Fentanyl Use in French General Practice: A Mixed-Methods Study Based on a Voluntary Online Survey. - Guastella, Virginie; Gueganno, Emeline; Bertin, Célian; Balayssac, David; Pereira, Bruno; Authier, Nicolas (Pain & Therapy, 2026)