Reasons for allowing and refusing generic substitution and factors determining the choice of an interchangeable prescription medicine: a survey among pharmacy customers in Finland.

Background: Generic substitution (GS) was introduced in Finland in 2003 and supplemented with a reference price system (RPS) in 2009. Patients play a vital role in the acceptance of GS and the use of less expensive generic medicines. The objective of this study was to explore Finnish pharmacy customers' experience with allowing and refusing GS.