Successful pain control in a patient with a desmoid tumor complicated by having selected the medicine considering the pharmacokinetic of the opioid

ABSTRACT

<b>Case</b> The patient was a man in his 40s who had undergone proctocolectomy for familial polyposis coli and extensive resection of the small intestine for removal of an intra-abdominal desmoid tumor. He presented to our hospital with abdominal pain caused by residual desmoid tumor, and diarrhea associated with the short bowel syndrome. Adequate pain control could not be achieved even with simultaneous application of 5 sheets of 100 μg/h transdermal fentanyl patches. Subsequently, the patient was treated mainly with 270 mg/day of a slow-release morphine preparation; however, the pain control remained unsatisfactory. At our hospital, the pain treatment was switched to 240 mg/day of morphine solution, which yielded prompt reduction of the pain intensity from 9/10 to 1/10 on the numerical rating scale. <b>Discussion</b> Morphine is mainly absorbed from the small intestine. The initially insufficient pain control in this patient may have been attributable to the short bowel syndrome and diarrhea causing rapid excretion of the morphine before it was absorbed. Morphine solution, in contrast, starts to be absorbed approximately 10 minutes after administration, allowing adequate absorption, leading to successful pain control, even in the present patient with the short bowel syndrome.