Lorazepam

Lorazepam(中文:[[ ]]) is a short-acting benzodiazepine with anticonvulsant, anxiolytic, sedative, muscle relaxant properties. It is used:

• In the short-term treatment of severe anxiety disorders;
• As a hypnotic in the short-term treatment of insomnia;
• As an anticonvulsant (particularly in the management of status epilepticus and febrile convulsions)
• As a sedative for those who are being mechanically ventilated
• Chemotherapy-induced nausea and vomiting

Pronunciation

Lorazepam 0.5mg

Lorazepam 1mg

Drug Names

Generic Name 藥名	HA Code 藥物代碼	Classification藥物分類
Lorazepam Tablet 0.5 mg	LORA01	P1S1S3 & Part 1 Dangerous Drug
Lorazepam Tablet 1 mg	LORA02	P1S1S3 & Part 1 Dangerous Drug
Lorazepam Tablet 2 mg	LORA03	P1S1S3 & Part 1 Dangerous Drug

Mechanism of Action

• Lorazepam is a benzodiazepine.
• Gama-Aminobutyric acid (GABA) is an inhibitory neurotransmitter, acting on the GABA receptors in the central nervous system (CNS), thus inhibiting the nerve impulses.
• It acts on the benzodiazepine receptors in the brain and the spinal cord. Benzodiazepine receptors in the CNS are linked with GABA receptors as a complex.
• Lorazepam by binding to the benzodiazepine receptors results in activation of the GABA-benzodiazepine receptor complex, resulting in inhibition of nerve impulses, overall depression of brain and spinal cord.
• The anticonvulsant properties of lorazepam come from binding to sodium channels.

Dosage

Anxiety	By mouth ADULT: 1 – 4 mg daily in divided doses ELDERLY: 0.5 – 2 mg daily in divided doses
Insomnia associated with anxiety	By mouth ADULT: 1 – 2 mg daily, to be taken at bedtime
Acute panic attacks	By mouth ADULT: 25 – 30 micrograms/kg every 6 hours if required; Usual dose: 1.5 – 2.5 mg every 6 hours if required
Conscious sedation for procedures	By mouth ADULT: 2 – 3 mg to be taken the night before operation 2 – 4 mg to be taken 1 – 2 hours before operation
Premedication	By mouth 2 – 3 mg to be taken the night before operation 2 – 4 mg to be taken 1 – 2 hours before operation
Status epilepticus Febrile convulsions Convulsions due to poisoning	By slow intravenous injection CHILD 1 month – 11 years: 100 micrograms/kg (max. per dose 4 mg) for 1 dose, then 100 micrograms/kg after 10 minutes (max. per dose 4 mg) if required for 1 dose, to be administered into a large vein CHILD 12 – 17 years: 4 mg for 1 dose, then 4 mg after 10 minutes if required for 1 dose, to be administered into a large vein ADULT: 4 mg for 1 dose, then 4 mg after 10 minutes if seizures continue or recur
Chemotherapy-induced nausea and vomiting	By mouth ADULTS: 1 to 2 mg may be added to antiemetic therapy with domperidone or metoclopramide for the prophylaxis of nausea and vomiting. The addition of lorazepam may be helpful in the prevention of anticipatory symptoms because of its anxiolytic, sedative and amnestic effects.

Side Effects

Sedative drugs, including alprazolam, have been associated with an increased risk of death. Possible side effects include:

Very common (>10% of incidence) or Common (1-10% of incidence)	Shakiness and unsteady walk (especially in the elderly) Trembling, and other problems with muscle control or coordination Confusion (especially in the elderly) Amnesia Drowsiness the next day sedation Muscle weakness Paradoxical increase in aggression
Infrequent (0.1 -1% of incidence)	Dysarthria Gastro-intestinal disturbances Gynaecomastia Low blood pressure Incontinence Urinary retention Slurred speech Tremor Vertigo Visual disturbances
Rare (<0.1% of incidence)	Apnoea Blood disorders Jaundice Respiratory depression hypersensitivity reactions

Overdosage can produce CNS depression and coma.

Paradoxical reactions (the opposite of what is to be expected) may occur. Symptoms include

• aggression, rage
• mania, agitation, and restlessness
• hallucinations, inappropriate behavior
• twitches and tremor

Pharmacokinetics

Oral bioavailability	Lorazepam is well absorbed after oral doses.
Onset of action	Peak plasma concentrations occur about 2 hours after an oral dose; and after 10 to 30 minutes when given as a rectal solution.
Metabolism	Lorazepam is metabolized in the liver
Elimination half-life	Lorazepam is excreted in the urine. The half-life of Lorazepam ranges from 10 – 20 hours.