Source of information: Drugbank (External Link). Last updated on: 3rd July 18
*Trade Name used in the content below may not be the same as the HSA-registered product.
Active Ingredient / Synonyms
o-Chlorooxazepam | o-Chloroxazepam | Lorazepam |
A benzodiazepine used as an anti-anxiety agent with few side effects. It also has hypnotic, anticonvulsant, and considerable sedative properties and has been proposed as a preanesthetic agent.
For the management of anxiety disorders, and for treatment of status epilepticus.
Mechanism of Action
Lorazepam binds to an allosteric site on GABA-A receptors, which are pentameric ionotropic receptors in the CNS. Binding potentiates the effects of the inhibitory neurotransmitter GABA, which upon binding opens the chloride channel in the receptor, allowing chloride influx and causing hyperpolerization of the neuron.
Lorazepam, a benzodiazepine not transformed to active metabolites, is used to treat anxiety, status epilepticus, and for sedation induction and anterograde amnesia.
Readily absorbed with an absolute bioavailability of 90% when given orally. When intramuscularly administered, lorazepam is completely and rapidly absorbed. It achieves max serum concentration in 3 hours. The max serum concentration of a 4 mg dose is 48 ng/mL.
1.3 L/kg. Unbound lorazepam can cross the blood-brain-barrier via passive diffusion.
Lorazepam is hepatically metabolized and is extensively conjugated to the 3-0-phenolic glucuronide. This is an inactive metabolite and is eliminated mainly by the kidneys.
When a single 2 mg oral dose is give to healthy subjects, 88±4% of the administered dose was recovered in urine and 7±2% was recovered in feces. The percent of administered dose recovered in urine as lorazepam glucuronide was 74±4%. Only 0.3% of the dose was recovered as unchanged lorazepam, and the remainder of the radioactivity represented minor metabolites.
Parenteral administration = 14±5 hours; Oral administration = 2 hours.
Total clearance, parenteral administration = 1.1±0.4 mL/min/kg.
The most important clinical adverse event caused by lorazepam is respiratory depression. LD50, mouse, oral = 1850 mg/kg.
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