Medicine shortages and glaucoma care: a time-series analysis indicating population-level consequences of a national timolol eye drop shortage.

INTRODUCTION: Medicine shortages can disrupt glaucoma management and necessitate therapeutic substitution. Understanding how shortages affect access to first-line treatments for glaucoma is important for optometrists when monitoring intraocular pressure control, and pharmacists when counselling patients and coordinating care during periods of limited medicine availability. Timolol, a non-selective beta-blocker, is a first-line treatment for glaucoma and ocular hypertension and has experienced international shortages in recent years. Between August 2024 and May 2025, Australia experienced a nationwide shortage of timolol-containing eye drops, raising concerns regarding continuity of care, access to treatment, and therapeutic substitution. AIM: To descriptively examine the impact of the 2024-2025 timolol eye drop shortage on dispensing patterns of antiglaucoma medicines in Australia and assess the contribution of imported products in mitigating the shortage. METHOD: A retrospective drug utilisation study was conducted using publicly available aggregate Pharmaceutical Benefits Scheme (PBS) and Repatriation PBS dispensing data from January 2020 to August 2025. Monthly dispensings of antiglaucoma preparations (ATC S01E) were standardised per 100,000 population and analysed using descriptive time-series methods. Dispensing trends were compared before, during, and after the shortage, with stratification by timolol formulation, therapeutic class, and product type (locally supplied versus overseas imports). RESULTS: The late 2024 and early 2025 timolol shortage was associated with a sustained decline in dispensing of single-ingredient extended-release timolol, decreasing from approximately 40 dispensings per 100,000 population per month before the shortage to 1.07 by March 2025. Dispensing of standard-release timolol increased temporarily in October 2024 before declining in a similar pattern. Overseas imports accounted for 24.3% of all timolol dispensings during the shortage period and peaked at 87% of timolol dispensings in March 2025. Despite regulatory approval of imported products, overall timolol utilisation remained below pre-shortage levels. Alternative therapeutic classes, including prostaglandin analogues and carbonic anhydrase inhibitors, showed modest increases in dispensing, suggesting potentially limited therapeutic substitution. CONCLUSION: The timolol shortage disrupted access to a cornerstone first-line treatment for glaucoma. Regulatory intervention through the approval of imported products partially mitigated the shortage but did not restore utilisation to pre-shortage levels in Australia. Future shortage management strategies should prioritise rapid policy activation and closer alignment of imported products with formulations routinely available in Australia.