What is the risk of interaction between opioid analgesics and monoamine oxidase inhibitors (MAOIs)?

Source: South West Medicines Information and Training Area: Evidence > Medicines Q & A . The use of most MAOIs with opioids is contraindicated by most, but not all manufacturers. (There are significant variations between UK and US literature). . Pethidine is the only commonly used opioid to have been reported to cause serotonin syndrome when used with MAOIs. . Some opioid analgesics are associated with a risk of serotonin syndrome in combination with MAOIs due to inhibition of serotonin re-uptake. Other combinations may result in opioid toxicity due to CYP450 enzyme inhibition by the MAOI. . Any trials conducted in this field are not recent and measure different outcomes from those now included in the definition of serotonin syndrome. This means almost all information is based on case reports. . Morphine is a widely recommended alternative to pethidine in patients receiving MAOIs, though starting at a low dose and titrating to clinical response would be advised. The patient should be monitored for signs of opioid toxicity. ...
Source: NeLM - Mental Health - Category: Psychiatry Source Type: news