Naldemedine-induced Opioid Withdrawal Syndrome in a Patient with Breast Cancer without Brain Metastasis.

Opioid-induced-constipation (OIC) can be treated by naldemedine and other peripherally acting mu-opioid receptor antagonists (PAMORA) via a novel mechanism. We describe the case of a 52-year-old female outpatient who developed OIC while receiving oxycodone for pain due to cancer with multiple bone metastases. Although she did not have brain metastasis, opioid withdrawal syndrome (OWS) developed after taking naldemedine orally. Her Clinical Opiate-Withdrawal Score (COWS) was 19 (moderate symptoms). However, she recovered from OWS on intravenous fentanyl and a continuous infusion of oxycodone. She did not develop OWS thereafter and was discharged two days after recovery.