title: A population-based study of the use of selective serotonin reuptake inhibitors before and after introduction of generic equivalents.
abstract: OBJECTIVE
  Generic drugs are less expensive than their branded equivalents, but receive limited promotion. This study sought to examine how user rates of individual selective serotonin reuptake inhibitors (SSRIs) changed after the introduction of their generic equivalents.
  
  
  METHODS
  Administrative health and census data were used to examine the rates of use of all 6 SSRIs from 1996 to 2009 in the province of Manitoba (population of 1.2 million). The primary outcome measure was a comparison of the rates of use in the pre- and post-generic periods, using generalized estimating equations. Secondary analyses were stratified by specialty of physician prescriber.
  
  
  RESULTS
  Escalating rates of use of branded SSRIs in the pre-generic period significantly decreased after generic versions became available (all Ps < 0.001). Incident use of sertraline and paroxetine continued to decrease throughout the post-generic period (1.5% and 1.9% quarterly decreasing rates, respectively). During the years when generic sertraline, fluoxetine, and fluvoxamine were available, their use declined while branded paroxetine and citalopram use continued to increase. Use of branded citalopram, sertraline, and paroxetine prescribed by general practitioners (GPs) increased at rates significantly higher than when prescribed by psychiatrists (all Ps < 0.001).
  
  
  CONCLUSIONS
  The introduction of cheaper generic alternatives of SSRIs paradoxically resulted in their use diminishing rather than increasing. With the exception of escitalopram, branded SSRIs tended to be preferentially used, compared with available less expensive generic SSRIs. These patterns were more pronounced for prescriptions by GPs.
authors.affiliation: Departments of Psychiatry and Psychology, University of Manitoba, Winnipeg, Manitoba. jbolton@hsc.mb.ca
authors.forename: James M
authors.initials: JM
authors.lastname: Bolton
authors.forename: Matthew
authors.initials: M
authors.lastname: Dahl
authors.forename: Jitender
authors.initials: J
authors.lastname: Sareen
authors.forename: Murray W
authors.initials: MW
authors.lastname: Enns
authors.forename: William D
authors.initials: WD
authors.lastname: Leslie
authors.forename: David M
authors.initials: DM
authors.lastname: Collins
authors.forename: Silvia
authors.initials: S
authors.lastname: Alessi-Severini
mesh_terms: D000328:Adult; D000928:Antidepressive Agents / Q000191:economics / Q000494:pharmacology / Q000627:therapeutic use; D003863:Depression / Q000188:drug therapy* / Q000191:economics; D016527:Drug Costs / Q000706:statistics & numerical data; D011307:Drug Prescriptions / Q000191:economics / Q000706:statistics & numerical data; D004363:Drug Utilization / Q000191:economics / Q000706:statistics & numerical data; D016568:Drugs, Generic / Q000191:economics / Q000494:pharmacology / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008350:Manitoba; D054539:Medication Therapy Management / Q000191:economics / Q000706:statistics & numerical data; D057240:Patient Preference / Q000191:economics / Q000523:psychology; D017060:Patient Satisfaction / Q000191:economics / Q000706:statistics & numerical data; D010818:Practice Patterns, Physicians' / Q000191:economics / Q000706:statistics & numerical data; D017367:Selective Serotonin Reuptake Inhibitors / Q000191:economics / Q000494:pharmacology / Q000627:therapeutic use; D013810:Therapeutic Equivalency
chemical_list: D000928:Antidepressive Agents; D016568:Drugs, Generic; D017367:Selective Serotonin Reuptake Inhibitors