Do policies that allow access to unregistered antimicrobials address the unmet need? Australia as a case study of a high-income country with universal healthcare.

Background: Ensuring timely and equitable access to effective and optimal antimicrobials is crucial for optimal patient care, to minimize the use of less appropriate treatment options and reduce the risk of antimicrobial resistance (AMR).

Objectives: To determine the average time for new antibacterials to gain registration for use in Australia after obtaining marketing approval internationally, and to quantify the use of 'new' and older unregistered antimicrobials in Australian clinical practice between 2018 and 2023.

Methods: Two data sources were utilized to estimate the usage of antimicrobials not registered for use in Australia. Annual hospital inpatient usage data were sourced from the National Antimicrobial Utilisation Surveillance Program (NAUSP) and data on Special Access Scheme (SAS) applications for unregistered antimicrobial was sourced from the Australian Government Department of Health and Aged Care.

Results: Between 2018 and 2023 there were 36 131 applications to access unapproved antimicrobials in Australia. In 26.6% of cases, access to an unapproved antimicrobial was for the treatment of a critically ill patient. Levofloxacin, pyrazinamide, tetracycline and pristinamycin were the most frequently accessed unregistered antimicrobials. Applications for 'new' antibacterials increased from 55 in 2018 to 249 in 2023. Inpatient use of nine new antibacterials was reported in Australian hospitals in 2023, two registered and seven unregistered.

Conclusions: Unapproved antimicrobials are frequently accessed by clinicians for patients unable to be treated with registered antimicrobials in Australia. Policy reform and economic incentives are required to support the registration of antimicrobials needed for otherwise untreatable infections and to ensure the sustainability of supply.