CASE PRESENTATION: A 60-year-old male was emergently admitted to our university hospital for the sudden onset of severe
back pain. Abdominal CT imaging revealed that the vertebral body of the ninth thoracic vertebra was occupied by bone
metastasis and crushed, which caused his
back pain. He received
warfarin 3.5 mg/day for
atrial fibrillation and
tapentadol 100 mg p.o. daily for
pain relief. The prothrombin time-international normalized ratio (PT-INR) was maintained at >2.2. The patient's history included
diabetes mellitus and
hypertension, but his laboratory test was unremarkable with the exception that his eGFR was 34 ml/min.Initially, a
fentanyl dermal patch was used instead of
tapentadol to avoid interactions with
warfarin. We started concomitant administration of
oxycodone and 2.4 g/day of
acetaminophen while monitoring the PT-INR because
acetaminophen increased the PT-INR to 2.93. A continuous
intravenous infusion of
oxycodone was introduced, in increments of the dose, resulting in an increase of the PT-INR to 3.41, which is required to reduce the dose of
warfarin to 1.5 mg. Because of the lack of effective
pain relief,
methadone was introduced and the dose was gradually increased. The PT-INR was not changed and the dose of
warfarin was not changed. An infusion of
oxycodone and oral
methadone was used to allow the patient to walk in his room, and he was later transferred to the palliative hospital.
CONCLUSIONS: