Each week we will aim to bring out a concise email that provides 4-5 key pieces of information addressing a specific issue in clinical therapeutics.
This week: Benzodiazepines
James Shankie-Williams, Clinical Pharmacist, Ward MM
Following the recent two-part series of Clinical Pearls about insomnia, here are some important points about benzodiazepines:
- Benzodiazepines are commonly used for the treatment of insomnia, anxiety and some forms of epilepsy (treatment and occasionally prevention), as well as in pre-medication before surgery, induction of anaesthesia, conscious sedation (midazolam) and acute alcohol withdrawal (diazepam). Diazepam is also used as a muscle relaxant.
- Due to the rapid development of tolerance (loss of efficacy) and possibility of dependence (addiction), if possible benzodiazepines should only be used regularly for a short period of time (up to 2-3 weeks).
- These medications often have a much longer lasting effect in the elderly, hence, long-acting benzodiazepines should be avoided in the elderly. These include diazepam (half-life up to 80 hours), clonazepam (half-life up to 54 hours), clobazam and nitrazepam (half-life up to 48 hours).
- Drug interactions can increase the half-life of some benzodiazepines further. Medications that inhibit hepatic enzyme CYP 3A4 can significantly increase the half-life of alprazolam, diazepam and midazolam. These medications include clarithromycin, diltiazem, erythromycin, fluconazole, fluvoxamine, itraconazole, ketoconazole, voriconazole, verapamil and grapefruit juice.
- Preferred benzodiazepines (those with short half-lives and lots of clinical data) in the elderly include temazepam (insomnia), oxazepam (anxiety/agitation) and midazolam (anxiety/agitation).
- All benzodiazepines are in Appendix D of Schedule 4 (S4D) except for alprazolam and flunitrazepam, which are in Schedule 8 (S8).
Please consider these issues when preparing or interpreting RMMR reports or education sessions. Contributions of content or suggested topics are welcome and should be sent directly to email@example.com.