Effect of concomitant opiate ingestion on paracetamol levels in acute overdose.
OBJECTIVE
To assess whether the co-ingestion of opiates in acute paracetamol overdose has an effect on the paracetamol level 4 h after ingestion.


METHODS
A prospective observational study was performed in the emergency department of a teaching hospital. The paracetamol levels at 4 h of consecutive patients who had taken an overdose of either paracetamol alone or in conjunction with an opiate were collected over a 4-month period. The data were then analysed.


RESULTS
After exclusions, the results of 21 patients who took paracetamol alone and 20 who took paracetamol and an opiate showed that paracetamol levels were significantly lower at 4 h if there was co-ingestion of an opiate. Analysis shows that opiate ingestion is a predictor for paracetamol levels at 4 h.


CONCLUSIONS
Co-ingestion of opiate decreases the serum paracetamol level at 4 h. If opiate and paracetamol are taken together, there is a case for a repeat measurement of the paracetamol level if the level at 4 h is lower than would be expected in selected patients.
Reddick
Andrew D
AD
Emergency Department, Ninewells Hospital, Dundee DD1 9SY, UK. andrew.reddick@nhs.net
Hodge
Kirsten
K
Morrison
William G
WG
D000082:Acetaminophen / Q000097:blood* / Q000493:pharmacokinetics / Q000506:poisoning; D000293:Adolescent; D000328:Adult; D000368:Aged; D000701:Analgesics, Opioid / Q000494:pharmacology / Q000506:poisoning*; D004347:Drug Interactions; D005260:Female; D005746:Gastric Emptying / Q000187:drug effects; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D019370:Observation; D011446:Prospective Studies; D055815:Young Adult
D000701:Analgesics, Opioid; D000082:Acetaminophen