Opioid toxicity after oxycodone/naloxone to oxycodone conversion: case series

Combination preparations of oxycodone/naloxone are marketed to aid in the management of opioid induced bowel dysfunction, with caution advised in prescribing in cases of liver dysfunction. This case series demonstrates four cases of patients with normal liver function tests who developed significant opioid toxicity on conversion from combination oxycodone/naloxone to oxycodone at equivalent doses, necessitating significant dose reduction. In each case, a cause for intra-hepatic shunting such as cirrhosis, porto-systemic collaterals or thrombosis were identified, highlighting these as cautionary features when prescribing combination preparations of oxycodone/naloxone and the possible need for dose reduction if converting to oxycodone.