Pethidine Fluoxetine

A 43 year old man was premedicated for endoscopy with intravenous midazolam 2 mg and pethidine 50 mg). He immediately became agitated and restless. His blood pressure rose to 180/100 mmHg, he sweated, had widely dilated pupils, and had diarrhea. Over the next 90 minutes his condition remitted without specific treatment. He then reported that he had been taking fluoxetine (20 mg every other day), which he had stopped taken about 2 weeks before. 

The symptoms described here resemble the 5HT toxicity syndrome (SEDA-25,16) and suggest that pethidine can provoke this reaction when combined with SSRIs, as it can with monoamine oxidase inhibitors. The report is also a useful reminder that the active metabolite of fluoxetine, norfluoxetine, has a half-life of about 1 week and would still have been present at the time of endoscopy, even though fluoxetine had been stopped 14 days before. 

SSRIs OPIOIDS 1. Possible 1 analgesic effect of oxycodone and tramadol 2. T serotonin effects, including possible cases of serotonin syndrome, when opioids (oxycodone, pethidine, pentazocine, tramadol) are co-administered with SSRIs (fluoxetine and sertraline) 3. SSRIs may t codeine, fentanyl, methadone, pethidine and tramadol levels 1. Uncertain. Paroxetine inhibits CYP2D6, which is required to produce the active form of tramadol. 2. Uncertain 3. SSRIs inhibit CYP2D6-mediated metabolism of these opioids 1. Consider using an alternative opioid 2. Look for signs of T serotonin activity, particularly on initiating therapy 3. Watch for excessive narcotization... 

Clinically important, potentially hazardous interactions with aminophylline, ciprofloxacin, dextromethorphan, entacapone, fluoxetine, fluvoxamine, MAO inhibitors, meperidine, pethidine, pseudoephedrine, SSRIs... 

A 43-year-old man who had been taking fluoxetine approximately every other day experienced symptoms of the serotonin syndrome immediately after receiving pethidine 50 mg intravenously for an endoscopic procedure. ... 

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