Lorazepam
Lorazepam is an intermediate-acting benzodiazepine used in adults for the short-term treatment of anxiety, status epilepticus and procedural sedation. It potentiates GABA-A signalling, with relevant dependence and cumulative sedation risks.
- Chemical formula
- C15H10Cl2N2O2
- CAS number
- 846-49-1
- ATC code
- N05BA06
- Molecular weight
- 321.16 g/mol
- Drug class
- Benzodiazepine
- Also known as
- WY-4036, Lorazepam
What is it?
Lorazepam is a 1,4-benzodiazepine first marketed in the 1970s and now widely used in anxiety, acute seizures and pre-anaesthetic sedation. It is supplied as oral tablets, oral concentrate and parenteral solution and is dispensed only on prescription in most jurisdictions. Lorazepam has the advantage of glucuronide metabolism that does not depend on cytochrome P450, which is relevant in older adults and in hepatic disease.
Mechanism of action
Lorazepam binds the benzodiazepine site of the GABA-A receptor and allosterically enhances the action of the inhibitory neurotransmitter GABA. The increased chloride conductance hyperpolarises neurons in the cortex, limbic system, brainstem and spinal cord, producing anxiolytic, sedative, hypnotic, anticonvulsant and muscle-relaxant effects. The intensity and balance of these effects depend on dose and route of administration.
Pharmacokinetics
Lorazepam is well absorbed after oral or sublingual administration, with peak plasma concentrations after one to two hours. Plasma protein binding is approximately 85%. The drug undergoes hepatic glucuronidation to inactive metabolites, without significant cytochrome P450 involvement. The terminal half-life is approximately 10 to 20 hours. Mild hepatic impairment does not require dose adjustment, but cumulative sedation is possible with repeated dosing in older patients.
Indications
Lorazepam is approved in adults for the short-term management of anxiety disorders and anxiety-related insomnia, for the acute treatment of generalised tonic-clonic seizures and status epilepticus (parenteral form), and for pre-anaesthetic sedation. According to clinical guidelines, anxiety prescriptions should be limited to short-term use at the lowest effective dose. It is not indicated for primary depression or for chronic insomnia outside specialist contexts.
Safety profile
Common adverse effects include sedation, drowsiness, dizziness, ataxia and memory impairment. The combination with alcohol, opioids or other CNS depressants increases the risk of severe sedation and respiratory depression. Tolerance, physical dependence and withdrawal symptoms occur with chronic use. According to the prescribing information, gradual tapering is required at the end of treatment, and abrupt discontinuation should be avoided. Caution is needed in older adults, in respiratory disease and in the perioperative setting.
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Frequently asked questions
How is lorazepam different from alprazolam? ▾
Both are benzodiazepines acting on the GABA-A receptor, but lorazepam has a longer half-life of 10 to 20 hours and is metabolised by glucuronidation, with no major involvement of cytochrome P450. Alprazolam has a shorter half-life and depends on CYP3A4. Lorazepam is therefore often preferred in elderly patients, hepatic disease or polypharmacy. The choice between them is made by the prescriber based on indication, comorbidity and concomitant medication.
Can lorazepam be taken sublingually? ▾
Yes. Sublingual administration is approved in some jurisdictions and provides a similar onset to oral administration with a similar bioavailability. The tablet is held under the tongue until dissolved. According to the prescribing information, the dose, frequency and duration are the same as for oral use, and the same precautions about CNS depressants and dependence apply.
Is lorazepam used for status epilepticus? ▾
Yes. Intravenous lorazepam is recommended in many clinical guidelines as a first-line treatment for status epilepticus in adults, alongside diazepam and midazolam. Its longer duration of effect compared with diazepam may reduce seizure recurrence after the first dose. According to the prescribing information, intravenous administration must be performed by trained personnel with monitoring of respiration and blood pressure.
How should lorazepam be discontinued? ▾
After short-term use, lorazepam can be discontinued without significant difficulty. After prolonged use, abrupt discontinuation may cause withdrawal symptoms including rebound anxiety, insomnia, tremor and, rarely, seizures. According to the prescribing information, gradual tapering over weeks to months under medical supervision is preferred, with the schedule individualised to dose, duration and patient response.
What are the main contraindications for lorazepam? ▾
Lorazepam is contraindicated in known hypersensitivity to benzodiazepines, in severe respiratory insufficiency, in narrow-angle glaucoma, in sleep apnoea syndrome and in severe hepatic insufficiency. Caution is required in older adults, in patients with substance use disorders and during pregnancy and breastfeeding. According to the prescribing information, the medical history must be reviewed by a clinician before any prescription.
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