Pharmacology · Benzodiazepines
Lorazepam !
An intermediate-acting benzodiazepine, first choice for stopping status epilepticus. It has no active metabolites, which suits older adults.
Updated 2026-11-01
The figure shows diazepam, a benzodiazepine that occupies the same site, bound to the human GABA-A receptor (α1β2γ2) with GABA; no structure with lorazepam is available.
Mechanism of action
Lorazepam binds the benzodiazepine site of the GABA-A receptor and makes GABA open the chloride channel more often, so neurons are inhibited. It is simply conjugated with glucuronic acid in the liver to an inactive product, without the cytochrome P450 steps that slow other benzodiazepines in older adults.
- Binds the benzodiazepine site of the GABA-A receptor
- GABA opens the chloride channel more often
- Neurons are inhibited: seizures stop, anxiety eases
- Glucuronidated to an inactive product and excreted
Pharmacokinetics
- Absorption
- Bioavailability by mouth about 90%
- Metabolism
- Glucuronidation to an inactive glucuronide; no active metabolites
- Elimination
- In the urine as the glucuronide
- Half-life
- About 12 hours
Indications
- Status epilepticus (injection) Status epilepticus →
- Anxiety disorders and short-term relief of anxiety Generalized anxiety disorder →
- Sedation and reduced recall before surgery (injection)
Adverse effects
Common
- Sedation and tiredness
- Dizziness and unsteadiness
- Weakness
- Memory loss for events after the dose
Contraindications
- Hypersensitivity to benzodiazepines or the vehicle
- Acute narrow-angle glaucoma
- Sleep apnoea or severe respiratory insufficiency, unless ventilated (injection)
- Intra-arterial injection; premature infants (benzyl alcohol)
Key interactions
- Opioids
- Profound sedation, respiratory depression, coma and death
- Alcohol and other central nervous system depressants
- Additive sedation and breathing depression
- Valproate
- Higher lorazepam levels; the dose is reduced
- Probenecid
- Longer lorazepam effect
- Clozapine
- Marked sedation, low blood pressure, delirium and respiratory arrest
What is monitored
- Breathing, oxygen saturation and airway, especially after IV doses
- Seizure activity and level of consciousness
- Blood pressure
- Kidney function and acid-base status with prolonged infusions
Administration and safety
- IV: diluted with an equal volume of a compatible diluent and injected slowly
- Aspirate during injection to make sure it is not intra-arterial or extravasated
- Stored refrigerated and protected from light; discoloured solutions or precipitates are discarded
- Airway and ventilation equipment ready before IV use
Nursing care
- Before each dose, check level of alertness, breathing rate and oxygen saturation
- Ask about opioids, alcohol and other sedatives
- Prevent falls, especially in older adults (unsteadiness, confusion)
- Teach not to drive or drink alcohol and not to stop the medicine suddenly
- After a seizure: keep the airway open, place on the side and time any new seizure
Pregnancy and breastfeeding
Use late in pregnancy can cause sedation and withdrawal symptoms in the newborn, who is watched after birth.
Test yourself
Think of the answer, then tap the question to see it.
Why is lorazepam often chosen in older adults or liver disease?
It is only glucuronidated, with no active metabolites, so it accumulates less.
How is lorazepam injection prepared before IV use?
It is diluted with an equal volume of compatible diluent and injected slowly.
Which antiseizure medicine raises lorazepam levels?
Valproate.
Related drugs
Related conditions
← Back to the class: Benzodiazepines
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - LORAZEPAM tablet (DailyMed (U.S. National Library of Medicine), 2026); DailyMed - LORAZEPAM injection, solution (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); 6X3X: Human GABAA receptor alpha1-beta2-gamma2 subtype in complex with GABA plus diazepam (RCSB Protein Data Bank, 2020).
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Representative model, for educational purposes only.