title: Potential for drug interactions in hospitalized cancer patients.
abstract: OBJECTIVE
  To quantify the frequency of potential drug interactions unrelated to chemotherapy in cancer patients admitted to our institution, and to define risk factors for such interactions.
  
  
  METHODS
  Charts of 100 consecutive hospitalized cancer patients were reviewed. Patients receiving chemotherapy and/or hormone therapy were excluded, as were patients admitted for intensive care. Drug-drug interactions were screened with Drug Interaction Facts software, and manually by the authors. Potential interactions were graded by levels of severity (severe, moderate, minor) and significance (one to five, with one representing the highest level of evidence).
  
  
  RESULTS
  The median age of the patients was 67 years, and the length of hospital stay and the number of drugs per patient were 6 days and eight drugs, respectively. In 63 patients 180 potential interactions were detected. Of the potential interactions, 18.3% were severe, 56.7% were moderate, and 25% were minor. Approximately 7%, 18% and 13% of potential interactions were graded as level 1, 2 and 3, respectively. In multivariate analysis, prescriptions with eight or more drugs (P=0.0004) and six or more days of hospital stay (P=0.014) were independent risk factors for potential interactions.
  
  
  CONCLUSIONS
  Potential drug interactions are common among hospitalized cancer patients. Length of hospital stay and number of prescribed drugs are risk factors.
authors.affiliation: Department of Medical Oncology, Albert Einstein Hospital, Avenue Albert Einstein 627/701, Sao Paulo, Brazil. Rachelri@terra.com.br
authors.forename: Rachel Pimenta
authors.initials: RP
authors.lastname: Riechelmann
authors.forename: Frederico
authors.initials: F
authors.lastname: Moreira
authors.forename: Oren
authors.initials: O
authors.lastname: Smaletz
authors.forename: Everardo D
authors.initials: ED
authors.lastname: Saad
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D064420:Drug-Related Side Effects and Adverse Reactions; D005260:Female; D006761:Hospitals; D006801:Humans; D007297:Inpatients; D007902:Length of Stay; D008297:Male; D008508:Medication Errors; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications; D012189:Retrospective Studies; D012307:Risk Factors