title: Potential drug-drug interactions between anti-cancer agents and community pharmacy dispensed drugs.
abstract: OBJECTIVE
  To identify the prevalence of potential drug-drug interactions between hospital pharmacy dispensed anti-cancer agents and community pharmacy dispensed drugs.
  
  
  METHODS
  A retrospective cohort study was conducted on the haematology/oncology department of the internal medicine ward in a large teaching hospital in Amsterdam, the Netherlands.
  
  
  METHODS
  Prescription data from the last 100 patients treated with anti-cancer agents were obtained from Paracelsus, the chemotherapy prescribing system in the hospital. The community pharmacy dispensed drugs of these patients were obtained by using OZIS, a system that allows regionally linked pharmacies to call up active medication on any patient. Both medication lists were manually screened for potential drug-drug interactions by using several information sources on interactions, e.g. Pubmed, the Flockhart P450 table, Micromedex and Dutch reference books.
  
  
  METHODS
  Prevalence of potential drug-drug interactions between anti-cancer agents provided by the hospital pharmacy and drugs dispensed by the community pharmacy.
  
  
  RESULTS
  Ninety-one patients were included in the study. A total of 31 potential drug-drug interactions were found in 16 patients, of which 15 interactions were clinically relevant and would have required an intervention. Of these interactions 1 had a level of severity ≥ D, meaning the potential drug-drug interaction could lead to long lasting or permanent damage, or even death. The majority of the interactions requiring an intervention (67%) had a considerable level of evidence (≥ 2) and were based on well-documented case reports or controlled interaction studies. Most of the potential drug-drug interactions involved the antiretroviral drugs (40%), proton pump inhibitors (20%) and antibiotics (20%). The anti-cancer drug most involved in the drug-drug interactions is methotrexate (33%).
  
  
  CONCLUSIONS
  This study reveals a high prevalence of potential drug-drug interactions between anti-cancer agents provided by the hospital pharmacy and drugs dispensed by the community pharmacy. It shows us there is need for an optimal medication surveillance mechanism to detect potential drug-drug interactions between these two groups of medication, especially because of the high toxicity of anticancer drugs and thus the severe consequences these interactions can have for the patient.
authors.affiliation: Hospital pharmacy, Medical Center Alkmaar, Wilhelminalaan 12, 1815, JD Alkmaar, The Netherlands. marshavoll@hotmail.com
authors.forename: Marsha L
authors.initials: ML
authors.lastname: Voll
authors.forename: Kim D
authors.initials: KD
authors.lastname: Yap
authors.forename: Wim E
authors.initials: WE
authors.lastname: Terpstra
authors.forename: Mirjam
authors.initials: M
authors.lastname: Crul
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D003157:Community Pharmacy Services; D004347:Drug Interactions; D064420:Drug-Related Side Effects and Adverse Reactions; D005260:Female; D006784:Hospitals, Teaching; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy; D009426:Netherlands; D012189:Retrospective Studies
chemical_list: D000970:Antineoplastic Agents