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Refilling and Switching of Antiepileptic Drugs and Seizure‐Related Events
Author(s) -
Gagne J J,
Avorn J,
Shrank W H,
Schneeweiss S
Publication year - 2010
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1038/clpt.2010.90
Subject(s) - medicine , medical prescription , odds ratio , confidence interval , epilepsy , antiepileptic drug , odds , pediatrics , emergency medicine , anesthesia , psychiatry , pharmacology , logistic regression
We sought to estimate the risk of seizure‐related events associated with refilling prescriptions for antiepileptic drugs (AEDs) and to estimate the effect of switching between brand‐name and generic drugs or between two generic versions of the same drug. We conducted a case–crossover study using health‐care databases from British Columbia, Canada, among AED users who had an emergency room visit or hospitalization for seizure (index seizure‐related event), defined using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD‐9) codes 345.xx (epilepsy and recurrent seizures) and 780.3x (convulsions), between 1997 and 2005. AED prescription refilling itself was associated with 2.3‐fold elevated odds of seizure‐related events when the refill occurred within 21 days before the index event (odds ratio (OR) 2.31; 95% confidence interval (CI) 1.56–3.44). The OR was 2.75 (95% CI 0.88–8.64) for refills that involved switching, yielding a refill‐adjusted OR for switching of 1.19 (95% CI 0.35–3.99). Refilling the same AED prescription was associated with an elevated risk of seizure‐related events whether or not the refill involved switching from a brand‐name to a generic product. Clinical Pharmacology & Therapeutics (2010) 88 3, 347–353. doi: 10.1038/clpt.2010.90