Antidepressant utilization in primary care in a Spanish region: impact of generic and reference-based pricing policy (2000-2004).

OBJECTIVE: To describe the evolution of antidepressant use in primary care in the Valencian region (Spain) from 2000 to 2004 and to analyze the effects of reference-based price and generic drugs introduction on drug utilization and cost saving.
METHODS: Retrospective observational study in primary care using sales data collected from antidepressant group (N06A), corresponding to the period 2000-2004. Defined daily dose (DDD)/1000 inhabitants per day were obtained as consumption data. Cost and cost/DDD rate evolution was related to reference price system implantation.
RESULTS: Antidepressant utilization progressively increased by 44.0% from 30.3 DDDs/1000 per day in 2000 to 43.5% in 2004. Selective serotonin reuptake inhibitors (SSRIs) comprised 77% of the total consumption where paroxetine, sertraline and fluoxetine were the most used drugs in 2004. The proportion of relative use and cost of fluoxetine declined after a reference price and the introduction of generic competitors were put into effect in 1999; cost/DDD was reduced by 1.8. Third-generation antidepressants showed a fast rising rate i.e. venlafaxine utilization multiplied by 2.2; this drug with the higher cost/DDD was not subjected to the reference price system. Reduction in citalopram utilization was related to a replacement by its recently marketed enantiomer escitalopram.
CONCLUSIONS: In 2004, reference price policy and the implementation of generic drugs reduced the antidepressant cost by DDD. However, antidepressant expenditure increased since 2000 due to a continued growth in consumption (SSRIs and novel agents) and a displacement of prescriptions to drugs that were not included in the reference price policy.