QJM Advance Access originally published online on November 12, 2008
QJM 2009 102(1):51-56; doi:10.1093/qjmed/hcn148
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Patterns of antiepileptic drug overdose differ between men and women: admissions to the Edinburgh Poisons Unit, 2000–2007
From the 1Scottish Poisons Information Bureau, The Royal Infirmary of Edinburgh, Edinburgh, UK and 2Medicines Management Team, NHS Lothian, Edinburgh, UK
Address correspondence to Dr W. Stephen Waring, Scottish Poisons Information Bureau, The Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh, EH16 4SA, UK. email: s.waring{at}ed.ac.uk
Received 23 July 2008 and in revised form 13 October 2008
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Background and Aims: Antiepileptic drugs are increasingly used in patients with psychiatric disorders who are at increased risk of self-harm. This might increase the likelihood that these agents are used as a means of overdose. This study was designed to examine the rate of occurrence of antiepileptic drug overdose between 2000 and 2007.
Methods: A retrospective observational study examined patterns of antiepileptic drug overdose in patients admitted to the Edinburgh Poisons Unit, and compared prescription data for the corresponding region. Data were compared using chi-square trend tests.
Results: There were 18 010 admissions to the Toxicology Unit, and 613 patients ingested at least one antiepileptic drug (3.4%). The most frequently implicated were carbamazepine, sodium valproate, phenytoin and lamotrigine, which corresponded with those most commonly prescribed. Women were more likely to ingest lamotrigine than men (P < 0.0001), and less likely to ingest sodium valproate (P = 0.0234). Patients that ingested antiepileptic drugs were more likely to be admitted to hospital for >1 day (22% vs. 8%, P < 0.0001) and need transfer to a psychiatric facility (14% vs. 7%, P < 0.0001).
Conclusions: Patients that ingested antiepileptic drugs required more intensive medical and psychiatric intervention compared to ingestion of other agents. Significant gender differences were noted in the specific antiepileptic drug ingested. Further work is required to establish whether this discrepancy may be explained by gender-based prescribing practices.