Description
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Mechanism of action: Lorazepam, like benzodiazepines, exerts its effect by binding to specific receptors at various sites in the central nervous system, potentiating effects of synaptic inhibition mediated by gamma-aminobutyric acid.
In doses greater than 2 mg, lorazepam not only impairs coordination, but also the speed and accuracy of execution. These effects were maximal at 4 hours or more after dosing.
Compared with other benzodiazepines, oral lorazepam 1 mg produced a degree of CNS depression comparable to that produced by diazepam 5 mg. The long duration of effect of lorazepam was correlated with a slow decrease in serum concentration.
Absorption: In a study with 6 subjects ingesting 4 mg lorazepam after an overnight fast and up to three hours post-dose, the highest plasma concentrations of lorazepam ranged from 40 to 70 ng/mL, which were achieved from 0.5 to 3.0 hours after dosing.
Delay periods were observed in 3 of the 6 subjects, prior to the onset of absorption. In all cases, absorption proceeded as an apparent first-order process, with an absorption half-life of 24.9 minutes. Elimination half-life values ranged from 8.4 to 23.9 hours. The highest concentration was 51.3 ± 5.7 ng/ml, this was reached at 1.7 ± 0.5 hours post-dose.
Elimination: Has a dose elimination half-life of 12 to 16 hours. The urinary route of excretion predominates in humans.
Distribution: It has a protein binding of 90%, so plasma concentrations are proportional to the amount administered.
Metabolism: The main metabolic route is through the divation of glucuronide, being the main metabolite in plasma and urine, not having significant activity on the central nervous system.
In plasma, the amounts of unchanged lorazepam and glucuronide are of the same magnitude. No lorazepam conjugates other than gluconic acid have been detected in biological materials.
The rapid divation of the essentially inactive and easily excreted water-soluble glucuronide is a common property of Lorazepam and other benzodiazepines.
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ATIVAN LORAZEPAM 2MG 40TABS
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