title: High prevalence of potential drug-drug interactions in patients with castration-resistant prostate cancer treated with abiraterone acetate.
abstract: OBJECTIVE
  Abiraterone acetate (AA), used to treat metastatic castration-resistant prostate cancer (mCRPC), inhibits androgen biosynthesis by blocking cytochrome P450 (CYP) 17A1. It also inhibits other cytochromes involved in the metabolism of various widely used medications. As such, there is presumably a high potential for drug-drug interactions (DDIs) that can diminish the efficacy of AA or concurrent medications, or increase the risk of DDI-related adverse events (AEs). However, the scale of AA-associated DDIs is currently unknown.
  
  
  METHODS
  We conducted a retrospective review of pharmacy records and electronic patient charts to retrieve individual drug histories and on-treatment AEs of mCRPC patients beginning AA therapy in a tertiary care setting. Potential DDIs were analyzed using two commercial databases, Lexicomp and Micromedex.
  
  
  RESULTS
  Eighty-four informative patients were identified. Sixty-five patients (77 %) and 44 patients (52 %) were flagged for one or more potential DDIs by the Lexicomp and Micromedex databases, respectively. One hundred eighty-four potential DDIs were identified overall, with a median of 1 DDI per patient in both databases. Possibly due to rigorous DDI screening before AA treatment initiation, we did not identify a definite instance of DDI-related AEs.
  
  
  CONCLUSIONS
  The use of commercial DDI databases suggests a substantial risk of potentially consequential DDIs in mCRPC patients undergoing AA therapy. However, prospective investigations with larger patient populations are required to better establish the clinical relevance of these DDIs.
authors: Sunnybrook Odette Cancer Centre, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada.|Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada.
authors: Rehana
authors: R
authors: Jamani
authors: Sunnybrook Odette Cancer Centre, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada.|Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada.
authors: Esther K
authors: EK
authors: Lee
authors: Sunnybrook Odette Cancer Centre, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada.
authors: Scott R
authors: SR
authors: Berry
authors: Sunnybrook Odette Cancer Centre, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada.
authors: Ronak
authors: R
authors: Saluja
authors: Sunnybrook Odette Cancer Centre, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada.|Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, ON, M5S 3M2, Canada.
authors: Carlo
authors: C
authors: DeAngelis
authors: Sunnybrook Odette Cancer Centre, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada.
authors: Angie
authors: A
authors: Giotis
authors: Sunnybrook Odette Cancer Centre, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada. urban.emmenegger@sunnybrook.ca.|Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada. urban.emmenegger@sunnybrook.ca.|Institute of Medical Science, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada. urban.emmenegger@sunnybrook.ca.
authors: Urban
authors: U
authors: Emmenegger
mesh_terms: D000069501:Abiraterone Acetate / Q000009:adverse effects* / Q000627:therapeutic use*; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000009:adverse effects* / Q000627:therapeutic use*; D016208:Databases, Factual; D004347:Drug Interactions; D006801:Humans; D008297:Male; D008875:Middle Aged; D019338:Polypharmacy; D064129:Prostatic Neoplasms, Castration-Resistant / Q000188:drug therapy*; D012189:Retrospective Studies
chemical_list: D000970:Antineoplastic Agents; D000069501:Abiraterone Acetate
keywords: Abiraterone acetate; Castration-resistant prostate cancer; Drug-drug interactions