Chemical formula: C₁₅H₁₀Cl₂N₂O₂ Molecular mass: 321.158 g/mol PubChem compound: 3958
Lorazepam is a benzodiazepine with anxiolytic, sedative and hypnotic properties.
Lorazepam is almost completely absorbed from the gastrointestinal tract and peak serum levels are reached in 2 hours.
Lorazepam is readily absorbed when given intramuscularly. Peak plasma concentrations occur approximately 60-90 minutes following intramuscular administration.
It is metabolised by a simple one-step process to a pharmacologically inert glucuronide. There are no major active metabolites.
Lorazepam is metabolised by a simple one-step process to a pharmacologically inactive glucuronide. There is minimal risk of accumulation after repeated doses, giving a wide margin of safety.
There are no major active metabolites.
The elimination half-life is about 12 hours and there is minimal risk of excessive accumulation.
The elimination half-life is about 12-16 hours when given intramuscularly or intravenously.
Lorazepam glucuronide, the major metabolite of lorazepam, has no demonstrable CNS activity in animals.
Oesophageal dilation occurred in rats treated with lorazepam for more than one year at 6mg/kg/day.
No evidence of carcinogenic potential emerged in rats and mice during an 18-month study with oral lorazepam.
A study of the mutagenic activity of lorazepam on Drosophila melanogaster indicated that this agent was mutationally inactive.
A pre-implantation study in rats was performed with oral lorazepam at a 20 mg/kg dose that showed no impairment of fertility.
Nonclinical research has shown that administration of anesthetic and sedation drugs that block N-methyl-D-aspartate (NMDA) receptors and/or potentiate gamma-aminobutyric acid (GABA) activity can increase neuronal cell death in the brain and result in long term deficits in cognition and behavior of juvenile animals when administered during the period of peak brain development. Based on comparisons across nonclinical species, the window of vulnerability of the brain to these effects is believed to correlate with human exposures in the third trimester of pregnancy through the first year of life, but may extend to approximately 3 years of age. While there is limited information of this effect with lorazepam, since the mechanism of action includes potentiation of GABA activity, a similar effect may occur. The relevance of these nonclinical findings to human use is unknown.
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