title: Drug-drug interactions in patients treated for cancer: a prospective study on clinical interventions.
abstract: BACKGROUND
  Drug-drug interactions (DDIs) are of major concern in oncology, since cancer patients typically take many concomitant medications. Retrospective studies have been conducted to determine the prevalence of DDIs. However, prospective studies on DDIs needing interventions in cancer patients have not yet been carried out. Therefore, a prospective study was designed to identify DDIs leading to interventions among ambulatory cancer patients receiving anticancer treatment.
  
  
  METHODS
  Patients starting with a new treatment regimen with i.v. or oral anticancer medication were asked to participate. The patients' medication was checked for DDIs by using drug interaction software. An expert team of clinical pharmacologists evaluated the relevance of these identified DDIs. If a DDI was qualified as potentially clinically relevant, an intervention was proposed to the treating (hemato)oncologist. Several variables were studied as determinants for performing an intervention. Descriptive statistics and uni- and multivariate logistic regression analyses were carried out.
  
  
  RESULTS
  In this study, 302 patients were included. A total of 603 DDIs were identified by the drug interaction software and judged by the expert team. Of all 603 DDIs, 120 DDIs were considered potentially clinically relevant. These 120 DDIs, present in a total of 81 patients, resulted in a clinical intervention already executed by the (hemato)oncologist in 39 patients (13%), while an additional intervention was proposed by a clinical pharmacologist in 42 patients (14%). The number of comorbidities and the number of 'over-the-counter' drugs were identified as determinants.
  
  
  CONCLUSIONS
  Clinical interventions on DDIs are frequently required among patients starting with anticancer therapy. Structured screening for these potentially clinically relevant DDIs, by (hemato)oncologists in close collaborations with clinical pharmacologists, should take place before the start and during anticancer treatment.
  
  
  BACKGROUND
  This study was registered at the Dutch Trial Registry under number NTR3760.
authors: Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands; Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam. Electronic address: r.w.f.vanleeuwen@erasmusmc.nl.
authors: R W F
authors: RWF
authors: van Leeuwen
authors: Department of Clinical Pharmacy, Deventer Hospital, Deventer; Department of Pharmacotherapy and Pharmaceutical Care, State University Groningen, Groningen.
authors: F G A
authors: FGA
authors: Jansman
authors: Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors: P M L A
authors: PMLA
authors: van den Bemt
authors: Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors: F
authors: F
authors: de Man
authors: Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors: F
authors: F
authors: Piran
authors: Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors: I
authors: I
authors: Vincenten
authors: Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam.
authors: A
authors: A
authors: Jager
authors: Department of Hematology, Erasmus MC Cancer Institute, Rotterdam.
authors: A W
authors: AW
authors: Rijneveld
authors: Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors: J D
authors: JD
authors: Brugma
authors: Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam.
authors: R H J
authors: RHJ
authors: Mathijssen
authors: Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands; Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors: T
authors: T
authors: van Gelder
mesh_terms: D061605:Administration, Intravenous; D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000009:adverse effects*; D015897:Comorbidity; D004347:Drug Interactions; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D054539:Medication Therapy Management; D008875:Middle Aged; D015999:Multivariate Analysis; D009369:Neoplasms / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology; D009426:Netherlands / Q000453:epidemiology; D004366:Nonprescription Drugs / Q000009:adverse effects; D016017:Odds Ratio; D010607:Pharmacy Service, Hospital; D019338:Polypharmacy; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012984:Software; D055815:Young Adult
chemical_list: D000970:Antineoplastic Agents; D004366:Nonprescription Drugs
keywords: cancer; drug–drug interactions; medication review; pharmacodynamics; pharmacokinetics; pharmacology