Abstract
BackgroundParacetamol (acetaminophen) is generally considered a safe medication, but is associated with hepatotoxicity at doses above doses of 4.0 g/day, and even below this daily dose in certain populations.MethodsThe Nova Scotia Prescription Monitoring Program (NSPMP) in the Canadian province of Nova Scotia is a legislated organization that collects dispensing information on all out-of-hospital prescription controlled drugs dispensed for all Nova Scotia residents. The NSPMP provided data to track all paracetamol/opioids redeemed by adults in Nova Scotia, from July 1, 2005 to June 30, 2010. Trends in the number of adults dispensed these prescriptions and the numbers of prescriptions and tablets dispensed over this period were determined. The numbers and proportions of adults who filled prescriptions exceeding 4.0 g/day and 3.25 g/day were determined for the one-year period July 1, 2009 to June 30, 2010. Data were stratified by sex and age (<65 versus 65+).ResultsBoth the number of prescriptions filled and the number of tablets dispensed increased over the study period, although the proportion of the adult population who filled at least one paracetamol/opioid prescription was lower in each successive one-year period. From July 2009 to June 2010, one in 12 adults (n = 59,197) filled prescriptions for over 13 million paracetamol/opioid tablets. Six percent (n = 3,786) filled prescriptions that exceeded 4.0 g/day and 18.6% (n = 11,008) exceeded 3.25 g/day of paracetamol at least once. These findings exclude non-prescription paracetamol and paracetamol–only prescribed medications.ConclusionsA substantial number of individuals who redeem prescriptions for paracetamol/opioid combinations may be at risk of paracetamol-related hepatotoxicity. Healthcare professionals must be vigilant when prescribing and dispensing these medications in order to reduce the associated risks.
Highlights
Paracetamol is generally considered a safe medication, but is associated with hepatotoxicity at doses above doses of 4.0 g/day, and even below this daily dose in certain populations
The Acute Liver Failure Study Group found that the median dose among American patients with unintentional overdose causing acute liver failure was 7.5 g per day, range of 1.0-78 g
Paracetamol-induced hepatotoxicity as a result of intentional or unintentional overdose is the most common drug-related cause of acute liver failure (ALF) in the USA, UK, Canada and most European countries, accounting for about one-half of all cases in the USA. [4,8,12,13,14,15] In the USA, about 150,000 poisoning cases were attributed to paracetamol in 2009, according to the Annual Report of the American Association of Poison Control Center’s National Poison Data System
Summary
Paracetamol (acetaminophen) is generally considered a safe medication, but is associated with hepatotoxicity at doses above doses of 4.0 g/day, and even below this daily dose in certain populations. [1,2,3] acute overdose [4], chronic doses over 4–6 g/day [5] and lower doses in certain populations [3,6,7,8], may be associated with hepatotoxicity. The Acute Liver Failure Study Group found that the median dose among American patients with unintentional overdose causing acute liver failure was 7.5 g per day, range of 1.0-78 g. Paracetamol-induced hepatotoxicity as a result of intentional or unintentional overdose is the most common drug-related cause of acute liver failure (ALF) in the USA, UK, Canada and most European countries, accounting for about one-half of all cases in the USA. Paracetamol toxicity can be difficult to diagnose, ; one study suggests that 18% of indeterminate cases of liver failure referred to an American tertiary care centre were due to unrecognized paracetamol toxicity [20]
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