Are prescribing initiatives readily transferable across classes: the case of generic losartan in Scotland?

Background: There are on-going initiatives in Scotland to improve the quality and efficiency of prescribing in primary care. Activities to enhance prescribing of angiotensin-converting enzyme inhibitors (ACEIs) versus angiotensin receptor blockers (ARBs) include prescribing guidance, guidelines, benchmarking, prescribing targets and financial incentives. These measures stabilised reimbursed expenditure for renin-angiotensin inhibitor drugs between 2001 and 2007 despite a 159% increase in volumes. Generic losartan was included in the Drug Tariff from July 2010. As there is no appreciable difference between ARBs, and the prices of generic losartan are falling, health boards should be actively encouraging its prescribing.

Aim: To primarily assess changes in utilisation patterns of losartan versus other ARBs after July 2010. Second, to assess the utilisation of generic versus originator losartan.

Method: We used an interrupted time series analysis of ARB utilisation, measured in defined daily doses (DDDs) before and after July 2010. Utilisation data were obtained from the NHS National Services Scotland Corporate Warehouse.

Results: There was no significant change in the utilisation pattern of losartan or other ARBs combined before or after the introduction of generic losartan. Losartan accounted for 32% of total ARBs 12 months after listing. Between 98 and 99% of losartan was prescribed generically. In March 2012, the price of losartan was 88% below prepatent prices with potential savings of ?8m per year.

Conclusion: Specific measures are needed to change prescribing habits especially with complex messages. The cost of deriving savings must be weighed against other quality initiatives and other ARBs losing or shortly losing their patents.