171 Case report: opioid-induced hyperalgesia with oral oxycodone

<h3>Background</h3> Opioid-induced hyperalgesia (OIH) describes a paradoxical response where opioids given for pain instead result in an increased pain response.¹ It has mostly been described when opioids are given perioperatively or as maintenance in opioid misuse.² There are limited reports in a palliative care context.^{1 3} <h3>Case Presentation</h3> A man in his 60s with metastatic oesophageal cancer was admitted for pain control. Pain was thought to be secondary to bony pelvic metastases. Oxycodone MR had been increased from 25 to 40mg BD one week earlier. Immediate release oxycodone use had escalated to around 130mg in the 24 hours prior to admission. On admission, he described severe pain all over. His skin was hypersensitive and he required Entonox to transfer. He was slightly drowsy with frequent myoclonic limb jerks. These symptoms were suspicious of opioid-induced hyperalgesia. Background analgesia was decreased by 25% and additional doses restricted. The following day he was more alert and in less pain. After 2 days, pain had improved further and skin hypersensitivity had resolved. Myoclonic jerks were less frequent. Background analgesia was reduced further, to 50% of the dose on admission. On day 5, pain remained controlled on the same analgesia. He was alert and able to mobilise. He was discharged several days later. <h3>Discussion</h3> This case illustrates that OIH can occur with oral opioids used at doses commonly used in palliative care. Recognising OIH can be challenging; there are no diagnostic criteria and it can be difficult to differentiate from increased pain due to disease progression or other causes. However, pain in OIH tends to be diffuse and allodynia and myoclonus often occur.³ <h3>Conclusion</h3> OIH is not common but it is important to recognise. Management can be complex but reduction of opioid dosage as an initial step can be effective. <h3>References</h3> Virani F, Miller M, Gilmour J. Opioid-induced hyperalgesia from alfentanil. <i>BMJ Supportive &amp; Palliative Care</i> 2020;<b>10</b>(3):310. Lee M, Silverman SM, Hansen H, Patel VB, Manchikanti L. A Comprehensive Review of Opioid-Induced Hyperalgesia. <i>Pain Physician</i> 2011;<b>14</b>(2):145–61. Murray-Brown F. 19 Management of opioid induced hyperalgesia. <i>BMJ Supportive &amp; Palliative Care</i> 2020;<b>10</b>(Suppl 1):A7.