CYP2D6 drug-gene and drug-drug-gene interactions among patients prescribed pharmacogenetically actionable opioids.
Mitchell R Knisely, Janet S Carpenter, Claire Burke Draucker and 4 others
PMID 29241501WHAT IT FOUND
In 30 patients newly prescribed codeine or tramadol, 10 had a gene or medication interaction affecting how they metabolize the opioid.
The opioid order alone did not show this risk.
Key findings
01Ten patients (33%) were adversely affected by a drug-gene or drug-drug-gene interaction.
02Five patients had adverse drug-gene interactions: two poor metabolizers, one intermediate metabolizer, and two ultra-rapid metabolizers.
03Five patients had drug-drug-gene interactions involving strong or moderate inhibitors that altered metabolizer status.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
Only 30 patients were studied. The study did not measure pain relief, adverse events, or other patient outcomes. It was a retrospective look at records and banked DNA, not a trial of pharmacogenetic testing or medication changes. A drug-drug-gene interaction was assumed when medication supply amounts overlapped, so actual concurrent use was not proven. The sample came from one public health system serving low-income patients, so it may not apply to other settings.
Declared interests
The authors declared no potential conflicts of interest.
The easy way to misread this
Do not read this as evidence that CYP2D6 testing should guide codeine or tramadol prescribing. It was an exploratory retrospective study of 30 patients, and it did not measure pain relief, adverse events, or whether acting on the interactions helped patients.