[Implementation of "aut idem" before and after introduction of rebate contracts]

Due to the aut-idem regulation pharmacies are obligated to substitute medications within the statutory health insurance system to low-priced generics or to dispense the prescribed drug (if only a compound is prescribed low-priced generics have to be dispensed). Since April 1st, 2007 pharmacies have to replace non-rebated by rebated drugs. We aimed to investigate if the prescribing of compounds and substitutions in pharmacies has changed after the introduction of rebate contracts.

We used claims data of the Gmünder ErsatzKasse (GEK) and drew 3 random samples of 1,000 relevant prescriptions each in October 2006, 2007 and 2008. After that, all relevant original prescriptions were screened.

Between October in 2006, 2007 and 2008, we observed no change in prescribing compounds only (6.0 %; 7.7 %; 6.8 %; p = 0.47). Prescribing compounds was associated with, e. g. dentists, small packages (N1 vs. N3) and antiinfectives. We found a considerable increase in medications that were substituted in pharmacies (2006: 11.3 %; 2007: 29.1 %; 2008: 39.2 %; p <0.0001).

Only through the introduction of rebate contracts an increasing amount of substituted medications took place in pharmacies. Before that, the aut-idem regulation had no considerable regulatory effect.