Changes in dispensing of medicines proposed for re-purposing in the first year of the COVID-19 pandemic in Australia

Abstract

Abstract Purpose We quantified changes in dispensing of common medicines proposed for “re-purposing” due to their perceived benefits as therapeutic or preventive treatments for COVID-19 in Australia, a country with relatively low COVID-19 incidence in 2020. Methods We performed an interrupted time series analysis and cross-sectional study using nationwide dispensing claims data (January 2017-November 2020). We focused on six subsidised medicines proposed for re-purposing: hydroxychloroquine, azithromycin, ivermectin, colchicine, corticosteroids, and calcitriol (Vitamin D analogue). We quantified changes in monthly dispensing and initiation trends during COVID-19 (March-November 2020) using autoregressive integrated moving average models (ARIMA) and compared characteristics of initiators in 2020 and 2019. Result In March 2020, we observed a 99% (95%CI 96%-103%) increase in hydroxychloroquine dispensing (of which approximately 30% attributable to new use), and a 201% increase (95%CI 186%-215%) in initiation, with a shift towards prescribing by general practitioners (42% in 2020 vs 25% in 2019) rather than specialists. These increases subsidised following regulatory restrictions on prescribing to relevant specialties. There was also a small but sustained increase in ivermectin dispensing over multiple months, with a 80% (95%CI 42%-119%) increase in initiation in May 2020 following its first identification as potentially disease-modifying in April 2020. Other than increases in March related to stockpiling among existing users, we observed no increases in initiation of calcitriol or colchicine during COVID-19. Dispensing of corticosteroids and azithromycin remained low after March 2020. Conclusions Most increases in dispensing observed early on during COVID-19 were temporary and appear to be related to stockpiling among existing users. However, we observed increases in initiation of hydroxychloroquine and ivermectin and a shift in prescribing patterns, indicating that a small proportion may be COVID-19 related. A quick response by regulators can help limit inappropriate repurposing to lessen the impact on medicine supply and patient harms. Key points In Australia, a country with low incidence of COVID-19 in 2020, most increases in dispensing of medicines proposed for re-purposing for treatment or prevention of COVID-19 were temporary and appeared to be related to stockpiling among existing users We observed a dramatic increase in new users of hydroxychloroquine in March and April 2020, with a shift toward prescribing by general practitioners instead of rheumatologists which subsided after the introduction of restrictions on its prescribing by non-specialists Dispensing of ivermectin also increased during COVID-19, but occurred later and was spread out over several months When such situations arise, a quick response by regulators can help limit inappropriate repurposing to reduce the potential for medicine supply shortages and patient harms