38-year-old patient with amputation of the left forefoot due to arteriopathy caused by Buerger's disease. In January 2008, Durogesic® 100 μg/h plus transmucosal fentanyl 400 μg rescue was prescribed for pain in the affected leg of 8/10 on the visual analogue scale (VAS). In one of the prescriptions for this drug, in September 2008, a pharmacy dispensed another commercial brand, after which he began at 4 h with pain 7/10 on the VAS, which he had not experienced for months, nausea and gastralgia, which were treated favourably with metoclopramide, improving gastric pain, and pantoprazole 40 mg every 12 h, and increasing the dose of oral transmucosal fentanyl from 400 to 600 μg. After 2 days, the patient was prescribed Durogesic® 100 μg/h, with a favourable resolution of the patient's allergic pathology.
