title: Switching treatment between mycophenolate mofetil and azathioprine in lupus patients: indications and outcomes.
abstract: OBJECTIVE
  To determine the reasons for changing treatment from mycophenolate mofetil (MMF) to azathioprine (AZA) or vice versa in lupus patients and to evaluate the effect of the change.
  
  
  METHODS
  Lupus patients were identified from the University of Toronto Lupus Clinic database. Global disease activity in the 6 months prior to the change in therapy and 6 months after the change was calculated. The reasons for changing therapy were identified.
  
  
  RESULTS
  One hundred eight switches occurred among 92 lupus patients: 89 switches from AZA to MMF and 19 from MMF to AZA. There was significant improvement in disease activity in the 6 months after drug switching compared to the 6 months prior to the switch when the reason was a drug failure. There was no statistically significant deterioration in disease activity in the 6 months after drug switching when the reason for the switch was a side effect, pregnancy, renal transplant, or financial. In the 19 patients who switched because of side effects, 15 (79%) had resolution of the side effects.
  
  
  CONCLUSIONS
  Switching from AZA to MMF is most often due to AZA failure, whereas switching from MMF to AZA is mostly due to side effects and pregnancy. When the reason for the switch was drug failure, improvement in disease activity occurred and there was a reduction of steroid dose after 6 months. When the reason for switching was something other than drug failure, there was no deterioration in global disease activity. Switching for side effects usually resulted in elimination of the side effect.
authors.affiliation: University of Toronto Lupus Clinic, Centre for Prognosis Studies in the Rheumatic Diseases, Toronto Western Hospital, Toronto, Ontario, Canada.
authors.forename: Hesham
authors.initials: H
authors.lastname: Al Maimouni
authors.forename: Dafna D
authors.initials: DD
authors.lastname: Gladman
authors.forename: Dominique
authors.initials: D
authors.lastname: Ibañez
authors.forename: Murray B
authors.initials: MB
authors.lastname: Urowitz
mesh_terms: D000293:Adolescent; D000328:Adult; D001379:Azathioprine / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D008180:Lupus Erythematosus, Systemic / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D009173:Mycophenolic Acid / Q000031:analogs & derivatives* / Q000627:therapeutic use; D011247:Pregnancy; D019233:Retreatment; D017211:Treatment Failure; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D007166:Immunosuppressive Agents; D009173:Mycophenolic Acid; D001379:Azathioprine