Implementation Aspects of a Medicines Shortage Policy Tool: Evidence from Australia's Serious Scarcity Substitution...

Medication shortages are a considerable and ongoing issue in healthcare, disrupting consumer access to medicines. Since 2021, Australia's national medicines regulator has issued Serious Scarcity Substitution Instruments (SSSIs), allowing pharmacists to substitute a specific therapeutically equivalent strength and/or formulation of a medicine without prior approval from a prescriber. The impact of SSSIs on utilisation of medicines has not been investigated.

To determine whether SSSIs are effective in addressing medicine shortages and meeting patients' needs.

This retrospective cohort study used aggregated pharmacy claims to examine the utilisation of 12 medicines, which had an SSSI. We calculated the percentage change in defined daily doses dispensed per 1000 population per day in the 11 months after SSSI implementation, compared with the previous 2 years. A percentage change of less than 20% was used to indicate success.

Following medicine shortages, utilisation fell for 10 of the 12 medicines examined. For eight of these medicines (amoxicillin, cefalexin, estradiol, fluoxetine, insulin degludec with insulin aspart, isosorbide mononitrate, vigabatrin, and warfarin) decreases in utilisation were minimised to < 20%. On average, SSSIs where all permitted substitute products were scarce (e.g., abatacept) were associated with larger decreases in use (between - 22 and - 68%) than those for which none or only some of the substitutes were in shortage (between - 45 and + 7%, respectively).

While product shortages led to decreases in medicines consumption, SSSIs appeared to be successful in limiting decreases. However, SSSIs were less likely to be successful when many of the permitted substitute products were also scarce.