Twenty-year trends in benzodiazepine dispensing in the Australian population

• Published in: Internal medicine journal 2014-01, Vol.44 (1), p.57-64
• Main Authors: Islam, M. M., Conigrave, K. M., Day, C. A., Nguyen, Y., Haber, P. S.
• Format: Article
• Language: English
• Subjects: anxiolytic drug; Ashton equivalent dose; Australia; benzodiazepine; Benzodiazepines - therapeutic use; defined daily dose; Drug Prescriptions - statistics & numerical data; Drug Utilization - trends; Drugs; Humans; hypnotic; Inappropriate Prescribing - statistics & numerical data; Insurance, Pharmaceutical Services - statistics & numerical data; Retrospective Studies; sedative; Therapeutic Equivalency
• ISSN: 1444-0903; 1445-5994
• DOI: 10.1111/imj.12315

Aim Considerable concern has been expressed about overprescribing of benzodiazepines and related harms. Past analyses have relied on World Health Organization‐defined daily doses (DDD) which are sometimes out of keeping with clinical usage. This study examines 20‐year (1992–2011) trends of benzodiazepine dispensing in Australia using both DDD and Ashton equivalent dose. Methods Data from the Drug Utilisation Sub‐Committee and the Pharmaceutical Benefits Scheme (PBS) website were analysed. Trends in number of prescriptions, DDD/1000 people/day and DDD/prescription were examined over time, and between states/territories. Results In the 20‐year period, 174 080 904 scripts were recorded, with temazepam the most dispensed benzodiazepine (35% of scripts), followed by diazepam (23%). Overall recorded utilisation fell from 27.7 DDD/1000 people/day in 1992 to 20.8 in 2011 (24.9% decrease). There were striking changes in use of individual benzodiazepines over time, with reductions in oxazepam and flunitrazepam and dramatic increases in alprazolam. Since 1998, there has been a steady increase, albeit modest, in per script DDD. The DDD/1000 people/day for items dispensed through PBS/Repatriaton‐PBS was highest in Tasmania and lowest in Northern Territory. Conclusion Despite a modest overall decline in the amount of benzodiazepine dispensed, the level of use is still likely to reflect relative over‐prescribing given the paucity of accepted indications for long‐term use. Since 1998, there was a polynomial increase in quantity dispensed per script. The WHO‐defined DDD for clonazepam seems inappropriate and could impede monitoring of its abuse. Other problems include lack of national data for medications not subsidised on PBS/Repatriation PBS. A broad policy approach is required, not one which targets only one particular benzodiazepine.