Letters to the Editor
- Kevin McNamara, Bridin Murnion, Jonathan Brett
- Aust Prescr 2016;39:33
- 1 April 2016
- DOI: 10.18773/austprescr.2016.016
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I congratulate the authors of the recent article on benzodiazepines1 for highlighting that, although not as bad as in the 1980s,2 benzodiazepine abuse and misprescribing remain a problem, especially in the area of polysubstance abuse.
I would like to make a suggestion. Regarding the Table, I tend to classify flunitrazepam (also now a Schedule 8 drug) and nitrazepam as long-acting benzodiazepines. There are usually three groups of benzodiazepine cited for clinical action: short-, intermediate- and long-acting. The authors have grouped short and intermediate, but this can give a misleading impression to prescribers, especially regarding these two benzodiazepines notorious for their accumulation and morning-after effects. For example, the product information for nitrazepam states ‘elderly debilitated patients may show a significant increase in elimination half-life.’
The other minor point I would make is that the approximate half-life of diazepam in the Table (20–80 hours) is misleading. Its active metabolite nordiazepam has a half-life of 96 hours according to the product information, and is marketed as an active compound in some countries.
Finally, a little mnemonic to help students, GP trainees and addiction trainees with outpatient benzodiazepine withdrawal is TTT i.e. Ten per cent reduction in dose per week over Ten weeks with an exponential/terminal Taper.
Mental health specialty services and Alcohol and other drugs
Gold Coast Hospital and Health Service
Associate professor and Mental health discipline lead
Faculty of Health Sciences and Medicine
Gold Coast, Qld
Bridin Murnion and Jonathan Brett, the authors of the article, comment:
Thank you for your observations regarding the half-lives of nitrazepam and flunitrazepam. Indeed we feel that any use of benzodiazepines in elderly debilitated people carries a significant risk regardless of half-life. The Table is perhaps an arbitrary division of benzodiazepines based on half-life as there is a degree of inter-individual variability and, as you say, active metabolites are also important. The pharmacodynamic effects of each drug may also differ to some degree and this may also impact on toxicity.
Medical director, Mental health specialty services and Alcohol and other drugs, Gold Coast Hospital and Health Service
Associate professor and Mental health discipline lead, Faculty of Health Sciences and Medicine, Bond University Gold Coast, QLD
Senior Staff Specialist, Clinical Pharmacology and Addiction Medicine, Drug Health Services, Royal Prince Alfred Hospital, Concord Repatriation General Hospital, Sydney
Staff Specialist, Clinical Pharmacology and Addiction Medicine, Drug Health Services, Royal Prince Alfred Hospital, Sydney