RESUMO
Oral transmucosal fentanyl has been developed for the management of breakthrough pain in cancer patients. Buccal and sublingual fentanyl tablets have been licensed in Japan. However, the optimal use of oral transmucosal fentanyl has not been elucidated. We describe the treatment of cancer‒related pain using a 100μg fentanyl sublingual tablet and a 12.5μg/hr fentanyl patch in a 77 year‒old man with rectal cancer and thoracic vertebral metastasis. After the first use of the fentanyl sublingual tablet, the patient’s consciousness was impaired for 6 hours, however respiration was stable. This case shows that administration of fentanyl sublingual tablets may not be recommended for breakthrough pain incancer patients who are being treated with 30mg/day of oral morphine equivalent dose (20mg/day oxycodone, 12.5μg/hr fentanyl patch).