title: Generic switch after ramipril patent expiry is not associated with decreased pharmacy refill compliance: a retrospective study using the DAPI database.
abstract: OBJECTIVE
  For treatment success in chronic diseases such as hypertension, adequate adherence to long-term pharmacotherapy is a prerequisite. The purpose of this study was to evaluate whether switching from brand name ramipril to a generic product after patent expiry may negatively affect patients' refill compliance.
  
  
  METHODS
  Claims data for ambulatory prescriptions within the statutory health insurance system were evaluated. Patients were included if they had filled a ramipril prescription (index) for either brand name or generic ramipril products between September 2003 and June 2004. Patients had to be continuously treated with ramipril for at least 12 months before and after the index date. Patients with a change from brand name to generic product or vice versa during follow-up after the index date were excluded from the analyses, as were patients who could not be unequivocally allocated to characteristics of covariates. Refill compliance was analysed by calculating the medication possession ratio (MPR), assuming that patients were prescribed one unit dose per day (MPR(UD)).
  
  
  RESULTS
  In total, 142,690 and 79,191 patients were classified as brand name or generic therapy, respectively. Median MPR(UD) values were 0.95 and 0.96 (P < 0.001). In a logistic regression model adjusting for covariates, the probability for noncompliance (MPR(UD) < 0.8) was marginally lower in the generic compared with the brand name group (odds ratio 0.926, 99% confidence interval 0.901-0.951, P < 0.001).
  
  
  CONCLUSIONS
  These results suggest that refill compliance is not negatively affected by a physician-induced switch from brand name to generic ramipril products after patent expiry.
authors: Department of Pharmacology, Goethe-University Frankfurt, Frankfurt am Main, Germany.
authors: Miriam
authors: M
authors: Ude
authors: Katrin
authors: K
authors: Schuessel
authors: Renate
authors: R
authors: Quinzler
authors: Kristina
authors: K
authors: Leuner
authors: Walter E
authors: WE
authors: Müller
authors: Martin
authors: M
authors: Schulz
mesh_terms: D000959:Antihypertensive Agents; D003628:Database Management Systems; D016568:Drugs, Generic; D006801:Humans; D010330:Patents as Topic; D017257:Ramipril; D012189:Retrospective Studies
chemical_list: D000959:Antihypertensive Agents; D016568:Drugs, Generic; D017257:Ramipril