title: Antidepressant dosage taken by patients with bipolar disorder: factors associated with irregularity.
abstract: BACKGROUND
  This study analyzed regularity in the daily dosage of antidepressants taken by patients with bipolar disorder and identified the factors associated with irregularity.
  
  
  METHODS
  Daily self-reported medication dosage taken and mood ratings were available from 144 patients who received treatment as usual. All 144 patients took the same antidepressant for at least 100 days. One hundred eleven of these patients were also taking a mood stabilizer. Approximate entropy (ApEn) was used to measure serial regularity in daily dosage. Regularity is the tendency that values within a time series remain the same on incremental comparisons. Drug holidays (missing three or more consecutive days) were also determined. Generalized estimating equations (GEE) were used to estimate if any demographic or clinical variables were associated with regularity.
  
  
  RESULTS
  Although the mean percent of days missing doses was only 18.6%, there was a wide range of regularity in the daily antidepressant dosage. Drug holidays were common, occurring in 41% of the analyses. Factors significantly associated with irregularity were as follows: total number of psychotropic medications (p = 0.005), pill burden (p = 0.005), and depression (p = 0.015). Neither the percent of days missing doses nor the drug holidays were associated with any demographic or clinical factors. For patients taking both antidepressants and mood stabilizers, there was no significant difference in regularity in daily dosage between these drugs.
  
  
  CONCLUSIONS
  There can be considerable irregularity in daily dosage despite a low percent of days missing doses. Medication regimen complexity and depressed mood are associated with increased irregularity. Daily regularity in drug dosage may be more dependent on the individual than on the specific drug. Research on the clinical impact of irregularity in daily dosage of antidepressants is needed.
authors.affiliation: Department of Psychiatry and Psychotherapy, Medical Faculty, Technische Universität Dresden, Fetscherstr 74, Dresden, 01307 Germany.
authors.forename: Rita
authors.initials: R
authors.lastname: Bauer
authors.affiliation: ChronoRecord Association Inc, Fullerton, CA 92834 USA.
authors.forename: Tasha
authors.initials: T
authors.lastname: Glenn
authors.affiliation: Department of Psychiatry, Dalhousie University, Halifax, NS B3H 4R2 Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Alda
authors.affiliation: Department of Psychiatry, University of Missouri Kansas City School of Medicine, Kansas City, MO 64110 USA.
authors.forename: Kemal
authors.initials: K
authors.lastname: Sagduyu
authors.affiliation: Department of Psychiatry, University of Massachusetts, Worcester, MA 01655 USA.
authors.forename: Wendy
authors.initials: W
authors.lastname: Marsh
authors.affiliation: Department of Psychiatry, University of Toronto, Toronto, ON M5T 1R8 Canada ; Mood Disorders Center of Ottawa, Ottawa, K1G 4G3 Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Grof
authors.affiliation: Department of Psychiatry, University of California San Diego, San Diego, CA 92093 USA.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Munoz
authors.affiliation: Faculty of Life and Social Sciences, Swinburne University of Technology, Melbourne, Victoria 3122 Australia.
authors.forename: Greg
authors.initials: G
authors.lastname: Murray
authors.affiliation: Department of Psychiatry and Psychotherapy, Medical Faculty, Technische Universität Dresden, Fetscherstr 74, Dresden, 01307 Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Ritter
authors.affiliation: Department of Psychiatry and Psychotherapy, Medical Faculty, Technische Universität Dresden, Fetscherstr 74, Dresden, 01307 Germany.
authors.forename: Ute
authors.initials: U
authors.lastname: Lewitzka
authors.affiliation: Department of Psychiatry and Psychotherapy, Medical Faculty, Technische Universität Dresden, Fetscherstr 74, Dresden, 01307 Germany.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Severus
authors.affiliation: Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles (UCLA), Los Angeles, CA 90095 USA.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Whybrow
authors.affiliation: Department of Psychiatry and Psychotherapy, Medical Faculty, Technische Universität Dresden, Fetscherstr 74, Dresden, 01307 Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Bauer