title: Use of terfenadine and contraindicated drugs.
abstract: OBJECTIVE
  To assess changes in concurrent use of products containing terfenadine and contraindicated macrolide antibiotics (erythromycin, clarithromycin, troleandomycin) and imidazole antifungals (ketoconazole, itraconazole) following reports of serious drug-drug interactions and changes in product labeling.
  
  
  METHODS
  Retrospective review of computerized pharmacy claims.
  
  
  METHODS
  A large health insurer in New England.
  
  
  METHODS
  Health plan members with 1 or more paid pharmacy claims for products containing terfenadine between January 1990 and June 1994.
  
  
  METHODS
  Among persons with paid claims for terfenadine in any given month, percentage with a prescription for any contraindicated drug that alternatively was dispensed on the same day as ("same-day dispensing") or had therapy days that overlapped those of ("overlapping use") a prescription for terfenadine.
  
  
  RESULTS
  Concurrent use of terfenadine and contraindicated drugs declined over the study period. The rate of same-day dispensing declined by 84% from an average of 2.5 per 100 persons receiving terfenadine in 1990 to 0.4 per 100 persons during the first 6 months of 1994, while the rate of overlapping use declined by 57% (from 5.4 to 2.3 per 100 persons). Most cases involved erythromycin.
  
  
  CONCLUSIONS
  Despite substantial declines following reports of serious drug-drug interactions and changes in product labeling, concurrent use of terfenadine and contraindicated macrolide antibiotics and imidazole antifungals continues to occur.
authors.affiliation: Policy Analysis Inc, Brookline, Mass, USA.
authors.forename: D
authors.initials: D
authors.lastname: Thompson
authors.forename: G
authors.initials: G
authors.lastname: Oster
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D000935:Antifungal Agents / Q000627:therapeutic use*; D017291:Clarithromycin / Q000627:therapeutic use; D000075202:Contraindications; D004347:Drug Interactions; D004363:Drug Utilization; D004917:Erythromycin / Q000627:therapeutic use; D006634:Histamine H1 Antagonists / Q000627:therapeutic use*; D006801:Humans; D017964:Itraconazole / Q000627:therapeutic use; D007654:Ketoconazole / Q000627:therapeutic use; D010593:Pharmaceutical Services; D011356:Product Labeling; D012189:Retrospective Studies; D016593:Terfenadine / Q000627:therapeutic use*; D014217:Troleandomycin / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D006634:Histamine H1 Antagonists; D017964:Itraconazole; D004917:Erythromycin; D016593:Terfenadine; D014217:Troleandomycin; D017291:Clarithromycin; D007654:Ketoconazole