Utilisation and prescribing patterns of antipsychotic medication in the Scottish primary care setting (2010/11–2020/21)

Background: Most guidelines do not recommend one antipsychotic over the other, so there is likely to be variation among prescribing in Scotland. Previous studies on antipsychotic utilisation are either out-dated, have used limited methodologies, or do not examine the trends of individual antipsychotics. This study assessed the recent utilisation of antipsychotics in Scottish primary care and evaluated the trends seen. Methods: This repeated cross-sectional study used Prescription Cost Analysis datasets (covers all prescriptions dispensed in primary care setting) from 2010/11–2020/21. Antipsychotics use was measured using number of items dispensed/1000 inhabitants and Defined Daily Doses (DDDs)/1000 inhabitants/day. Results: Both utilisation metrics showed an increase in total antipsychotics (increased by 26.5%; 1.97 DDDs), an increase in atypicals (increased by 54.8%; 2.84 DDDs) and a decrease in typicals (decreased by 38.6%; 0.87 DDDs). In terms of atypicals, quetiapine had the highest number of items dispensed/1000 inhabitants (increased by 98.4%; 36.4 items), whereas Olanzapine had the highest number of DDD/1000 inhabitants/day (increased by 32.3%; 0.71 DDDs). For typicals, prochlorperazine had the highest number of items dispensed/1000 inhabitants but chlorpromazine had the largest number of DDD/1000 inhabitants/day over the study period and still the number of DDDs decreased by 49.2% (0.31 DDDs) over the 10 years. Conclusion: Antipsychotic utilisation has increased considerably, with atypical antipsychotics markedly taking the lead over typicals. Despite the popularity of certain antipsychotics, there is no clear evidence to suggest that one antipsychotic is more efficacious/tolerable than the other, which suggests that prescribing is influenced by other factors such as formulary preference.