Abstract

Naloxegol is a new peripherally acting mu-opioid receptor antagonist to treat opioid-induced constipation with supposedly no effect on opioid analgesia. We present a patient with cancer-related pain who developed acute opioid withdrawal symptoms due to an interaction between the opioid antagonist naloxone and naloxegol. He was treated with oxycodone sustained release because of poor pain control. For opioid-related constipation, he had been receiving naloxegol. He complained about worsening pain and constipation and oxycodone was switched to oxycodone/naloxone. Shortly after intake, he experienced acute severe agitation, anxiety, sweating, tachycardia, disorientation and yawning without improvement after intravenous midazolam. Only after intravenous morphine administration, symptoms were controlled. He was switched back to the previous oxycodone dose without naloxone, with naloxegol being maintained. In the light of this case we suggest to avoid the use of naloxone and naloxegol in combination, or at least, to use it with extreme caution and monitorisation of tolerance.