BACKGROUND: In order to increase price competition, government regulations focus 
on controlling drug costs. Drug costs after patent expiry are an area of 
particular interest because the substitution of branded medication with generics 
represents an opportunity for lowering drug costs. However, drug costs may not 
decrease after patent expiry, because of a lack of price competition and 
different national pricing systems.
AIM: The aim of this study was to investigate the trends in the use of generics 
after patent expiry for enalapril, fluoxetine and ranitidine and the subsequent 
changes, if any, in the costs of these medications.
METHODS: A drug-utilisation study was performed using data from a large sample 
of Dutch pharmacies. Both volumes (measured as defined daily doses [DDD] per 
1000 population) as well as drug costs (calculated per DDD) prior to and after 
patent expiry were calculated. Costs per DDD were compared using trend-line 
analysis. In addition, the relative market shares of the different trade 
channels (branded, parallel imported and generic) were compared before and after 
patent expiry.
RESULTS: The costs per DDD decreased for all three drugs and, as expected, these 
costs decrease more rapidly after patent expiry. Significant differences in the 
trend lines were found for enalapril and fluoxetine.
CONCLUSIONS: Despite relatively high reimbursement prices for generics in the 
Netherlands, this example from the Dutch pharmaceutical market demonstrates the 
benefit of generic substitution for containing pharmaceutical costs, which 
contrasts with concerns raised by the Dutch government.