title: Drug-drug interactions in pediatric oncology patients.
abstract: BACKGROUND
  Drug-drug interactions (DDIs) can negatively affect pharmacotherapy. However, pediatric DDI studies are scarce. We undertook an exploratory study to investigate prevalence and clinical relevance of DDIs between cytostatic and noncytostatic drugs in outpatient pediatric oncology patients.
  
  
  METHODS
  After informed consent and inclusion, the following information was collected: currently prescribed noncytostatic and cytostatic drugs, comorbidities, and use of over-the-counter (OTC) drugs, complementary and alternative medicines (CAMs), and dietary supplements. All medication was screened for DDIs according to two databases: Micromedex®Solutions and the Dutch drug database G-Standard. The researcher presented DDIs with an associated potential for adverse outcome and a proposal for intervention to three independent experts. If the experts considered a DDI to be potentially clinically relevant and requiring intervention, the physician was notified.
  
  
  RESULTS
  Seventy-three patients were included (median age 8.9 years). A total of 67 different DDIs were counted (66 in Micromedex®Solutions, 14 in G-Standard, and 13 DDIs in both databases). The medication reviews resulted in 35 interventions related to 11 different DDIs. The majority of DDIs concerned noncytostatic drugs (25/35) and one third occurred between cytostatic and noncytostatic drugs (10/35). The use of QTc-interval-prolonging drugs resulted in one intervention. The use of OTC drugs, CAM, or dietary supplements did not lead to DDIs.
  
  
  CONCLUSIONS
  This study resulted in a selection of 11 potentially clinically relevant DDIs for 73 outpatients in our pediatric oncology department. Interventions were formulated in close collaboration between physicians and clinical pharmacists. Future research should focus on assessing DDIs concerning QTc-interval prolongation.
authors.affiliation: Department of Pharmacy, Erasmus MC, Rotterdam, The Netherlands.|Faculty of Pharmacy, Utrecht University, Utrecht, The Netherlands.
authors.forename: T E
authors.initials: TE
authors.lastname: Balk
authors.affiliation: Department of Pharmacy, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: I H
authors.initials: IH
authors.lastname: van der Sijs
authors.affiliation: Department of Pharmacy, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: T
authors.initials: T
authors.lastname: van Gelder
authors.affiliation: Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands.
authors.forename: J J B
authors.initials: JJB
authors.lastname: Janssen
authors.affiliation: Department of Pediatric Hematology-Oncology, Erasmus MC-Sophia, Rotterdam, The Netherlands.
authors.forename: I M
authors.initials: IM
authors.lastname: van der Sluis
authors.affiliation: Department of Pharmacy, Erasmus MC, Rotterdam, The Netherlands.|Department of Medical Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands.
authors.forename: R W F
authors.initials: RWF
authors.lastname: van Leeuwen
authors.affiliation: Department of Pharmacy, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: F K
authors.initials: FK
authors.lastname: Engels
mesh_terms: D000293:Adolescent; D000970:Antineoplastic Agents / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D016208:Databases, Factual; D004347:Drug Interactions; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology* / Q000209:etiology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D015995:Prevalence
chemical_list: D000970:Antineoplastic Agents
keywords: cancer pharmacology; chemotherapy; drug-drug interactions; pediatric hematology/oncology; support care