title: Does substitution of brand name medications by generics differ between pharmacotherapeutic classes? A population-based cohort study in France.
abstract: OBJECTIVE
  The purpose of this study was to measure the rate of substitution failure to generic antiepileptic drugs (AEDs) compared to two other pharmacotherapeutic classes (neuroleptics, beta-blockers).
  
  
  METHODS
  We conducted a cohort study involving beneficiaries of the French health insurance system from January 2009 to November 2012. Substitution failure to generic drugs was estimated by the rate of switchback (i.e. from generic drug back to its branded drug). We selected the patients who had a dispensation of a branded AED for 60 days or more during the 90 days preceding the generic substitution. Cox proportional hazard regression was used to model time to switchback for antiepileptics vs. other therapeutic classes in the 90 days after generic substitution, adjusting for age, gender and polytherapy.
  
  
  RESULTS
  The cohort included 6727 patients of whom 1947 were exposed to AEDs, 2398 to neuroleptics and 2382 to beta-blockers. The switchback rate was 62% for AEDs. AED users were more likely to switch back as compared to beta-blocker (crude hazard ratio 1.87; 95% CI 1.68-2.07 for patients under 75) or neuroleptic users. The same observation was made in patients above 75 years (crude hazard ratio 1.36; 95% CI 1.16-1.60).
  
  
  CONCLUSIONS
  Compared to beta-blocker users, AED users were more likely to switch back to the branded drug, whereas this difference was not observed with neuroleptics. These results could reflect a poor acceptance of switching AEDs to generic compounds in France.
authors.affiliation: Laboratoire de Pharmacologie Médicale et Clinique de la Faculté de Médecine et du Centre Hospitalier, Universitaire de Toulouse, Toulouse, France.|INSERM UMR 1027, Faculté de Médecine, Université de Toulouse, Toulouse, France.
authors.forename: Alicia
authors.initials: A
authors.lastname: Molinier
authors.affiliation: Laboratoire de Pharmacologie Médicale et Clinique de la Faculté de Médecine et du Centre Hospitalier, Universitaire de Toulouse, Toulouse, France. aurore.palmaro@univ-tlse3.fr.|INSERM UMR 1027, Faculté de Médecine, Université de Toulouse, Toulouse, France. aurore.palmaro@univ-tlse3.fr.|CIC INSERM 1436 Université et Centre Hospitalier Universitaire de Toulouse, Toulouse , France. aurore.palmaro@univ-tlse3.fr.
authors.forename: Aurore
authors.identifier: http://orcid.org/0000-0002-5660-9224
authors.initials: A
authors.lastname: Palmaro
authors.affiliation: Laboratoire de Pharmacologie Médicale et Clinique de la Faculté de Médecine et du Centre Hospitalier, Universitaire de Toulouse, Toulouse, France.|INSERM UMR 1027, Faculté de Médecine, Université de Toulouse, Toulouse, France.|CIC INSERM 1436 Université et Centre Hospitalier Universitaire de Toulouse, Toulouse , France.|Centre Midi-Pyrénées de PharmacoVigilance, de Pharmacoépidémiologie et d'Informations sur le Médicament, Pharmacopôle Midi-Pyrénées, Centre Hospitalier Universitaire de Toulouse, Toulouse, France.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Rousseau
authors.affiliation: Laboratoire de Pharmacologie Médicale et Clinique de la Faculté de Médecine et du Centre Hospitalier, Universitaire de Toulouse, Toulouse, France.|INSERM UMR 1027, Faculté de Médecine, Université de Toulouse, Toulouse, France.|CIC INSERM 1436 Université et Centre Hospitalier Universitaire de Toulouse, Toulouse , France.
authors.forename: Agnès
authors.initials: A
authors.lastname: Sommet
authors.affiliation: Direction Régionale du Service du contrôle Médical de Midi-Pyrénées, Toulouse, France.
authors.forename: Robert
authors.initials: R
authors.lastname: Bourrel
authors.affiliation: Laboratoire de Pharmacologie Médicale et Clinique de la Faculté de Médecine et du Centre Hospitalier, Universitaire de Toulouse, Toulouse, France.|INSERM UMR 1027, Faculté de Médecine, Université de Toulouse, Toulouse, France.|Centre Midi-Pyrénées de PharmacoVigilance, de Pharmacoépidémiologie et d'Informations sur le Médicament, Pharmacopôle Midi-Pyrénées, Centre Hospitalier Universitaire de Toulouse, Toulouse, France.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Montastruc
authors.affiliation: Laboratoire de Pharmacologie Médicale et Clinique de la Faculté de Médecine et du Centre Hospitalier, Universitaire de Toulouse, Toulouse, France.|INSERM UMR 1027, Faculté de Médecine, Université de Toulouse, Toulouse, France.|Centre Midi-Pyrénées de PharmacoVigilance, de Pharmacoépidémiologie et d'Informations sur le Médicament, Pharmacopôle Midi-Pyrénées, Centre Hospitalier Universitaire de Toulouse, Toulouse, France.
authors.forename: Haleh
authors.initials: H
authors.lastname: Bagheri
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D016568:Drugs, Generic; D005260:Female; D005602:France; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D016568:Drugs, Generic
keywords: Antiepileptic; Beta-blockers; Generics; Neuroleptics; Primary care; Switchback