title: Weight loss dynamics during combined fluoxetine and olanzapine treatment.
abstract: BACKGROUND
  Fluoxetine and olanzapine combination therapy is rapidly becoming an effective strategy for managing symptoms of treatment-resistant depression. Determining drug-drug interactions, drug metabolism and pharmacokinetics is of particular interest for revealing potential liabilities associated with drug augmentation in special patient populations. In the current studies, we chronically administered fluoxetine and olanzapine in non-stressed rats to extend our previous findings regarding body weight dynamics.
  
  
  RESULTS
  Chronic fluoxetine (10 mg/kg) and olanzapine (5 mg/kg and 0.5 mg/kg) treatment decreased weight gain irrespective of olanzapine dosing. At the 10 mg/kg and 5 mg/kg dose, respectively, fluoxetine and olanzapine also significantly reduced food and water consumption. This pharmacodynamic event-related effect, however, was not observed at the 10 mg/kg and 0.5 mg/kg dosing paradigm suggesting differences in tolerability rates as a function of olanzapine dose. The decrease in weight gain was not associated with apparent changes in glucose metabolism as vehicle- and drug-treated rats showed undistinguishable serum glucose levels. The combination of fluoxetine and olanzapine in rats yielded drug plasma concentrations that fell within an expected therapeutic range for these drugs in psychiatric patients.
  
  
  CONCLUSIONS
  These data suggest that fluoxetine and olanzapine treatment decreases weight gain in rats; a pharmacodynamic event-related effect that differs considerably from what is observed in the clinical condition. The possibility of mismatched models regarding body weight changes during drug augmentation therapy should be seriously considered.
authors.affiliation: Department of Neuroscience, New York College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, New York 11568, USA. perronejennifer@hotmail.com <perronejennifer@hotmail.com>
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Perrone
authors.forename: Janet M
authors.initials: JM
authors.lastname: Chabla
authors.forename: Brian H
authors.initials: BH
authors.lastname: Hallas
authors.forename: Judith M
authors.initials: JM
authors.lastname: Horowitz
authors.forename: German
authors.initials: G
authors.lastname: Torres
mesh_terms: D000818:Animals; D001569:Benzodiazepines / Q000494:pharmacology; D005473:Fluoxetine / Q000494:pharmacology*; D008297:Male; D000077152:Olanzapine; D051381:Rats; D020318:Rats, Long-Evans; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology; D015430:Weight Gain / Q000187:drug effects / Q000502:physiology; D015431:Weight Loss / Q000187:drug effects* / Q000502:physiology
chemical_list: D001569:Benzodiazepines; D005473:Fluoxetine; D000077152:Olanzapine; D017367:Selective Serotonin Reuptake Inhibitors