Lorazepam

Absorption

Readily absorbed with an absolute bioavailability of 90% when given orally. When intramuscularly administered a dose of 4 mg, lorazepam is completely and rapidly absorbed and achieves a maximal serum concentration of 48 ng/ml in 15-30 minutes. When administered orally, the time to attained maximum concentration is observed to be of 2 hours.

Toxicity

The LD50 observed by oral administration in a mouse is of 1850 mg/kg. When an overdose administration is registered, signs of CNS and respiratory depression are rapidly observed. An overdose stage can result in profound sedation, deep respiratory depression, coma, and death. When overdose is observed, it is recommended to administer emergency symptomatic medical support with attention to produce an increase in lorazepam elimination.
There is no evidence of carcinogenicity nor mutagenicity. At doses higher than 40 mg/kg there is evidence of fetal resorption and increase in fetal loss.

Chemical properties

White Crystalline Solid

Originator

Tavor,Wyeth,Italy,1972

The Uses of Lorazepam

An anxiolytic, and anticonvulsant. Controlled substance (depressant)

Background

Lorazepam is a short-acting and rapidly cleared benzodiazepine used commonly as a sedative and anxiolytic. It was developed by DJ Richards, presented and marketed initially by Wyeth Pharmaceuticals in the USA in 1977. The first historic FDA label approval is reported in 1985 by the company Mutual Pharm.

Indications

Lorazepam is FDA-approved for the short-term relief of anxiety symptoms related to anxiety disorders and anxiety associated with depressive symptoms such as anxiety-associated insomnia. It is as well used as an anesthesia premedication in adults to relieve anxiety or to produce sedation/amnesia and for the treatment of status epilepticus.
Some off-label indications of lorazepam include rapid tranquilization of an agitated patient, alcohol withdrawal delirium, alcohol withdrawal syndrome, muscle spasms, insomnia, panic disorder, delirium, chemotherapy-associated anticipatory nausea and vomiting, and psychogenic catatonia.

Definition

ChEBI: Lorazepam is a benzodiazepine.

Manufacturing Process

The starting material was 2-amino-2',5-dichlorobenzophenone which was reacted with hydroxylamine and then with chloroacetyl chloride. The intermediate thus obtained is reacted with methylamine and then with acetic anhydride.
To a slightly warm suspension of 3-acetoxy-7-chloro-5-(o-chlorophenyl)-1,3- dihydro-2H-1,4-benzodiazepin-2-one thus obtained was added 4N sodium hydroxide solution with stirring. All the solid dissolved and soon a thick white solid precipitated out. The solid was filtered, washed well with water and recrystallized from ethanol. The product was isolated as a solvate with 1 mol of ethanol. When heated it loses the ethanol of solvation and melts at 166°C to 168°C.

brand name

Ativan (Baxter Healthcare); Ativan (Biovail); Loraz (Quantum Pharmics).

Therapeutic Function

Tranquilizer

General Description

Lorazepam, 7-chloro-5-(2-chlorophenyl)-3-dihydro-3-hydroxy-2H-1,4-benzodiazepine-2-one(Ativan), is the 2'-chloro derivative of oxazepam. In keepingwith overall SARs, the 2'-chloro substituent increases activity.As with oxazepam, metabolism is relatively rapid anduncomplicated because of the 3-hydroxyl group in the compound.Thus, it also has short half-life (2–6 hours) and similarpharmacological activity.

Biological Activity

Ligand at the GABA A receptor benzodiazepine modulatory site. Anxiolytic, anticonvulsant and sedative/hypnotic agent.

Pharmacokinetics

The effect of lorazepam in GABA-A receptors produces an increase in the frequency of opening of the chloride ion channel. However, for its effect to generate, the neurotransmitter is required. The anticonvulsant properties of lorazepam are thought to be related to the binding to voltage-dependent sodium channels in which the sustained repetitive firing gets limited by the slow recovery of sodium channels due to the benzodiazepine effect.
The effect of lorazepam seems to be very compartmental which was observed with a different generation of sleepiness and a dizziness effect.

Metabolism

Lorazepam is hepatically metabolized by CYP450 isoenzymes and extensively conjugated to the 3-0-phenolic glucuronide. This is an inactive metabolite and is eliminated mainly by the kidneys.