Lorazepam
Class: anxiolytic – short acting benzodiazepine
Indications (NB some may be unlicensed): short term use: anxiety, insomnia, premedication, muscle spasm, nausea/vomiting (anxiety related)
Contraindications/cautions: respiratory failure; severe hepatic impairment; renal impairment
Adverse reactions: common: sedation, dizziness, unsteadiness; less common: respiratory depression (high dose), disorientation, depression, disinhibition, amnesia, excitement
Metabolism/clearance: Mainly metabolised by glucuronidation
Interactions:
- additive CNS effects with other CNS depressants e.g. other benzodiazepines (e.g. midazolam), phenothiazines (e.g. chlorpromazine), tricyclic antidepressants (e.g. amitriptyline), opioids, alcohol
| Dosing: | ||
|---|---|---|
| anxiety | insomnia | |
| oral: | 1 to 3 mg/day in 2 to 3 doses (max. 10 mg/24 hours) | 1 to 2 mg at bedtime |
| subcut: | injection available (unregistered) but difficult to obtain | injection available (unregistered) but difficult to obtain |
| rectal: | not available | not available |
Syringe driver: not available
Mechanism of action: may enhance the effect of GABA, an inhibitory neurotransmitter in the CNS
Onset: oral: 20 to 30 minutes sublingual: shorter onset
Duration: oral: 6 to 8 hours Half life: 10 to 20 hours
Notes:
- lorazepam is a short acting benzodiazepine
- tablets may be tried sublingually
- not metabolised by metabolising enzymes CYP450 so less likely to interact with other drugs compared with other benzodiazepines
- theoretically most appropriate benzodiazepine to use in hepatic failure
- for approximate equivalent oral anxiolytic/sedative doses see clonazepam page
- for pharmacological properties of benzodiazepines see clonazepam page