discrepancies between n-acetyl cysteine prescription based on patient’s history and plasma acetaminophen level

background: fatalities from acetaminophen poisoning are common, but they are preventable by timely treatment with n-acetyl cysteine (nac). in many medical centers, nac is prescribed in keeping with the ingested dose of the drug as revealed through medical history. it seems to significantly differ from the real indications of nac administration based on plasma level of acetaminophen. overtreatment increases adverse drug reactions and it is time- consuming and costly. methods: acetaminophen plasma level was checked by hplc method in 170 admitted patients who had history of acute ingestion of more than 7.5 g acetaminophen within 4 to 24 hours prior to hospital admission. indications for nac prescription according to patient’s history and adaptation from acetaminophen plasma level in romack-mathew nomogram were matched. data were analyzed by spss software version 16.0. results: mean age of the patients was 21.8±6.05 years. in 75.8% of the patients, poisoning had occurred after suicidal attempts. acetaminophen plasma level was between less than 2 and 265 μg/ml (18.7±28.88, mean± sd). only in 18 (10.6%) cases, overtreatment had been performed. multiple logistic regression analysis showed that the number of suicidal attempts, number of ingested pills, and time of referral had positive relationships with acetaminophen plasma level. conclusion: if nac is prescribed only based on patient's medical history, overtreatment may take place.