Influence of lifting prescribing restrictions for losartan on subsequent sartan utilization patterns in Austria:...

Prescribing restrictions for angiotensin receptor blockers (ARBs) limited their utilization in Austria. Recently, generic losartan became available with its prescribing restrictions lifted while still in place for patented ARBs.

The main aim of this study is to assess the impact of the lifting of the prescribing restriction on utilization of losartan in ambulatory care versus other single ARBs, expenditure per defined daily dose (DDD) of losartan as well as total ARB expenditure and utilization of ARB combinations. Finally, to suggest potential measures that could be introduced to further enhance ARB-prescribing efficiency.

A quasi-experimental study of the utilization of different ARBs alone or in fixed dose combinations using a segmented time series. Utilization measured in DDDs, defined as 'the average maintenance dose of a drug when used in its major indication in adults'. Costs measured as total expenditure for different ARBs as well as their expenditure/DDD.

Losartan utilization increased significantly following the withdrawal of prescribing restrictions (p > 0.001). Utilization of single-sourced ARBs also increased , but the growth rate was appreciably reduced once restrictions were lifted for losartan (p > 0.01). As a result, total expenditure of single ARBs increased but at an appreciably lower rate than utilization, helped by total expenditure/DDD for losartan declining by 78% over the study period. There was continuing appreciable utilization of fixed-dose combinations.

Lifting of prescribing restrictions for losartan significantly enhanced its utilization, increasing ARB-prescribing efficiency, providing direction to other European authorities. Additional reforms are being considered to further switch utilization away from single-sourced ARBs to additionally improve prescribing efficiency as more multiple sourced ARBs become available.