Lorazepam (Ativan, Temesta) is a potent short-acting benzodiazepine
with all six of the intrinsic benzodiazepine effects: anxiolytic, sedative/hypnotic, anticonvulsant, antiemetic, and muscle relaxant.
It is prescribed for short-term treatment of insomnia, panic attacks, for acute seizures caused by epilepsy or anoxia (lack of oxygen), sedation in hospitalized patients, and for psychiatric crises involving serious anxiety, agitation, or violence. Lorazepam is also used as a pre-operative medication for its amnesic properties.
As are all benzodiazepines
, lorazepam is a GABAA
Lorazepam, being a high-potency and short-acting drug
has the potential for misuse and addiction
[top]Introduction to Lorazepam
Lorazepam (Ativan, Temesta) is a quickly absorbed, short acting, and potent benzodiazepine. Lorazepam has a short half-life
of 10 hours in part because none of its metabolites are pharmacologically active. But IV delivered lorazepam has efficacy between 82 and 100%; it enters cerebral tissue very quickly and is pharmacologically active there for up to 72 hours, much longer than diazepam
. This makes it a good treatment for acute seizures and status epilipticus (seizures lasting more than five minutes, a serious medical emergency). Because of its anticonvulsant and anxiolytic effects lorazepam is also used to treat symptoms of withdrawal
. Lorazepam’s quick action makes it a good choice for psychiatric crises involving agitation, panic, aggression or violence, and it is prescribed for intermittent severe anxiety such as experienced in relation to flying. Lorazepam is also administered preoperatively for its anxiolytic, sedating and amnestic effects, especially in patients with anxiety about surgery. As all benzodiazepines do, lorazepam works on the GABAA
receptor. Lorazepam has a high risk of abuse, dependence, and addiction given its potency and short half-life. [REF]
[top]Ways of Administration
Lorazepam for anxiety, panic and insomnia is usually taken orally in doses of 0.5 to 2mg. For emergent situations the preferred route of administration is IV, but the rectal administration and IM injection is also used. Injectable lorazepam is administered either by deep intramuscular injection
or intravenously. In addition to these routes of administration
, crushed lorazepam tablets are also insufflated (snorted) by recreational users.
[top]Effects of Lorazepam
The normal therapeutic effects of lorazepam include anxiolysis (anxiety reduction), amnesia (memory loss), disinhibition, muscle relaxation, sedation, and sleepiness. Lorazepam reduces tension and anxiety, calms one's state of mind, and encourages sleep. Since lorazepam use causes tolerance rapidly (within 4 weeks at some doses) and because psychological and physical addiction can occur within a matter of 1-3 months (depending on dosage), courses of treatment are limited to two weeks if possible. (REF)
[top]Combinations with Lorazepam
Combining Lorazepam with other central nervous system depressants
is dangerous because of the likely additive effects increasing respiratory depression to potentially fatal levels. These depressants include alcohol, other benzodiazepines, barbiturates, antipsychotics, sedative antihistamines, anticonvulsants, delirant and dissociative drugs
, muscle relaxants
, narcotic analgesics
, and anesthetics. MAO inhibitors, and other antidepressants
Injectable lorazepam combined with scopolamine has been shown to increase sedation and produce both hallucinations and irrational behavior.
Combining lorazepam with clozapine can produce increased sedation, excessive salivation, low blood pressure, loss of muscle coordination, delirium, and respiratory arrest. (REF)
The combination of lorazepam with valproate results in increased lorazepam blood levels and reduced lorazepam clearance. Combining lorazepam with probenecid may result in a more rapid onset or prolonged effect of lorazepam due to increased half-life and decreased clearance. Lorazepam dosage must be reduced by approximately 50% when combined with either of these medications. These effects are theorized to be due to inhibition of glucuronidation, the process responsible for metabolizing lorazepam to its pharmacologically inactive metabolites. (REF)
Theophylline and aminophylline may also reduce the sedative effects lorazepam.(REF)
[top]Different Uses for Lorazepam
Lorazepam is used recreationally for its anti-anxiety, relaxing, hypnotic and sedating effects. Therapeutically it is used to treat and prevent both acute seizures and alcohol withdrawal syndrome, as a treatment for catatonia,(REF) for rapid sedation in individuals who are agitated or violent, for insomnia, panic attacks, and anxiety. (REF)
[top]Pharmacology of Lorazepam
Lorazepam has an oral bioavailablity of >90%. The time for lorazepam to achieve peak plasma concentrations is 15 min - 2.5 hours, with an average of 1 - 1.5 hours. Taking lorazepam orally with food that has a moderate level of fat will delay absorption and reduce the amount absorbed. [REF] Lorazepam has a short half-life– less than 10 hours but is highly potent because of its high in vivo affinity for its GABAA
receptor. Lorazepam is a classical benzodiazepine (along with chlordiazepoxide
, lorazepam and temazepam
) because its attributes are multi-faceted and it produces all effects that epilepsy: pharmacology and pharmacokinetics.
Lorazepam works by activating the GABAA
receptor at the benzodiazepine (BZP) site. GABA levels in the brain are not increased by lorazepam, it potentiates naturally occurring GABA by binding to a benzodiazepine receptor site located on the post synaptic receptor plate in a GABAergic nerve terminal. Lorazepam’s presence there increases the CI conductance and thus increases GABA transmission, leading to the major inhibition of other neurotransmitters. This is how lorazepam creates sedation and its other effects. Glucuronidation by UGT, (uridine diphosphate glucuronosyltransferase.) is the primary pathway by which lorazepam is metabolized into its metabolites, all of which are pharmacologically inactive. Its excretion is primarily renal.
Mice : 3178 orally
Rat : >5000 orally
[top]Chemistry of Lorazepam
|Systematic(IUPAC) name:|| (RS)-9-chloro-6-(2-chlorophenyl)-4-hydroxy-2,5-diazabicyclo[5.4.0]undeca-5,8,10,12-tetraen-3-one|
|Synonyms:||7-Chloro-5-(2-chlorophenyl)-1,3-dihydro-3-hydroxy-2H-1,4-benzodiazepin-2-one, Wy-4036, Ativan, Emotival, Lorax, Lorsilan, Pro Dorm, Psicopax, Punktyl, Quait, Sedatival, Sedazin, Somagerol, Tavor, Temesta, Wypax|
|Molar mass:||321.16 g/mol |
|CAS Registry Number:||846-49-1|
|Melting Point:||166-168 ℃|
|Boiling Point:||no data|
|Flash Point:||no data|
|Solubility:||0.08 mg/mL (water), 3 mg/mL (chloroform), 14 mg/mL (alcohol), 16 mg/mL (propylene glycol), 30 mg/mL (ethyl acetate). Soluble to 100 mM in DMSO and to 40 mM in ethanol|
|Additionnal data:||pK1 1.3, pK2 11.5|
[top]The Dangers of Lorazepam
[top]Physical Health Risks
[top]Impaired Attention and alertness
People taking lorazepam who may drive, operate heavy machinery, or engage in other potentially dangerous physical activities should take great care. One is advised to take time first to learn how they react to lorazepam before engaging in any of these, since lorazepam, like all benzodiazepines, impairs attention and alertness.
[top]Lorazepam and Breastfeeding
The benefit to lactating mothers of taking lorazepam must be weighed against risks this poses to neonates from lorazepam in breast milk which has been shown to cause sedation, inability to suckle, and irritability.
[top]Drug Interactions with UGT inducers
Possible increase of lorazepam dose should be considered when taking UGT (uridine diphosphate glucuronosyltransferase) inducers such as phenobarbital, phenotoin, and rifampin. Since these induce increased activity of the main enzyme responsible for metabolizing lorazepam into its inactive metabolites, their use decreases lorazepam blood levels and therefore its effects, possibly precipitating withdrawal symptoms in lorazepam dependent or addicted individuals.
A study of sedative and anxiolytic involvement in poisoning deaths in New Zealand in 2001 found lorazepam to have been involved in 2 deaths, but to be among the safest of sedatives
with a rate of 1.9 deaths per million defined daily doses dispensed (compared to alprazolam
's 16, temazepam's 2.1, clonazepam
's 16.1, diazepam’s of 5.2 and zopiclone
's of 0.59.
[top]Mental Health Risks
[top]Hallucinations, Suicidal Ideation and Paradoxical Reactions
Lorazepam can in rare cases cause hallucinations, confusion, depression, suicidal and/or thoughts of self-harm. These are also potentially very serious, the medication should be stopped and immediate medical assistance sought. Paradoxical reactions also occur in which a person becomes hyperactive, agitated and hostile.
[top]Rebound Insomnia and Anxiety
Rebound insomnia and rebound anxiety can be caused when lorazepam is stopped too abruptly, especially if the use has been long term and/or at higher than normal therapeutic doses. effects have been shown to happen with as short a course of lorazepam as 7 days.
[top]Cognitive and Memory Deficiences
Lorazepam, like all benzodiazepines, there is health risk of causing forgetfulness, rebound amnesia, and difficulty with some cognitive tasks and concentration. Lorazepam has been shown to impair both explicit and implicit memory, unlike other benzodiazepines.
Like many medications, lorazepam can cause an allergic reaction, but this is uncommon. Symptoms of an allergic reaction may include swelling of lips, throat, tongue and face, trouble breathing and hives. If this occurs medical help must be sought immediately since allergic reactions progress very quickly and they can be fatal, though death as an outcome is fairly rare.
Given intravenously, lorazepam can be even more dependence and addiction causing than when taken orally, especially if intravenous use occurs over a protracted period of time. Stopping lorazepam without tapering may cause withdrawal. Lorazepam withdrawal symptoms can include headache, sweating, rebound insomnia and anxiety, dizziness, numbness/tingling of extremities, hypersensitivity to: sounds, light, noise, tactile sensations, and perceptual changes, involuntary movements, nausea, vomiting, diarrhea, loss of appetite, hallucinations/delirium, convulsions/seizures, tremor, abdominal cramps, myalgia, palpitations, tachycardia
, hyperreflexia, and hyperthermia
. Seizures may be more common for individuals with pre-existing seizure disorders or on drugs or medications that lower seizure threshold.
Lorazepam, especially used long-term (more than two to four weeks), can cause dependence and mental addiction. Abruptly stopping lorazepam in these circumstances may cause anxiety, tension, depression, insomnia, restlessness, agitation, confusion, irritability, dysphoria, derealization, panic attacks, vertigo, depersonalization, and short-term memory loss.
[top]Legal Status of Lorazepam
Lorazepam is a controlled substance 21 CFR 1308.14
In Australia Lorazepam is a Schedule 4 prescription-only substance. In New South Wales, Australia, as with other Benzodiazepines, it is a Schedule 4 Appendix D substance which means that no repeats may be authorized unless with prior approval of the NSW Ministry of Health.
[top]History of Lorazepam
[top]More Lorazepam Sections
[top]The Latest Lorazepam Threads
, fifteenth edition (2013)
Calculated from Atomic Weights of the Elements
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