Lorazepam chemical structure
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Lorazepam

Lorazepam (marketed under the brand names Ativan®, Temesta®, Tavor®) is a drug which is a benzodiazepine derivative. Pharmacologically, it is classified as a sedative-hypnotic, anxiolytic and anticonvulsant. more...

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Pharmacology and pharmacokinetics

Lorazepam is rapidly and nearly completely absorbed after any mode of application (oral, sublingual, i.m., i.v.). The onset of action is several minutes after i.v. injections, 30 to 45 minutes after oral/sublingual administration, and up to 1 hour after i.m. injections.

The duration of action depends on the dose, and is normally 6 to 12 hours. The half-life of lorazepam in patients with normal liver function is 11 to 18 hours. Therefore, 2 to 4 daily doses are often needed.

0.5mg (500µg) of lorazepam is equivalent to 5mg of diazepam . Other experts estimate a proportion of 1mg lorazepam to 5mg diazepam.

Indications

Lorazepam is indicated for:

  • Treatment of anxiety disorders
  • Short-term treatment of insomnia, particularly if associated with severe anxiety
  • Treatment of symptoms associated with alcohol withdrawal
  • As a premedication,
    • To facilitate unpleasant procedures, such as endoscopies and dental surgery.
    • To augment the action of the primary anaesthetic drug.
    • To produce varying degrees of anterograde amnesia for the duration of the procedure.
  • Long-term treatment of otherwise resistant forms of petit mal epilepsy
  • Acute therapy of status epilepticus
  • Acute therapy of catatonic states alone/or with haloperidol
  • As an initial adjunctive treatment for depressions, mania and psychosis
  • Treatment of acute delirium, preferrably together with haloperidol
  • Supportive therapy of nausea/emesis frequently associated with cancer chemotherapy, usually together with firstline antiemetics like 5-HT3-antagonists

Lorazepam is available in tablets and as a solution for intramuscular and intravenous injections. It is also available as a parenteral patch.

Dosage

Daily doses vary greatly from 0.5 mg bedtime for insomnia and 2.5 mg every 6 hours and more in the acute treatment of mania, before the firstline drugs (lithium, valproic acid) control the situation.

Catatonia with inability to speak is very responsive and sometimes controlled with a single dose of 2 mg oral or slow i.v. injection. Catatonia may reoccur and treatment for some days may be necessary. Sometimes haloperidol is given concomitantly.

The control of status epilepticus requires slow i.v. injections of 2 to 4 (or even 8) mg. Patients should be closely monitored for respiratory depression and hypotensive effects.

In any case, dose requirements have to be individualized especially in the elderly and debilitated patients in whom the risk of oversedation is greater. Safety and effectiveness of lorazepam is not well determined in children under 18 years of age, but it is used to treat serial seizures. With higher doses (preferably i.v.-doses) the patient is frequently not able to recall unpleasant events (anterograde amnesia) such as therapeutic interventions (endoscopies etc.), which is a desirable effect. But in these cases the risk is given that a patient later makes unjustified allegations of sexual abuse during treatment due to poor recall.

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Lorazepam Prevents Recurrence of Alcohol-Related Seizures - Statistical Data Included
From American Family Physician, 7/1/99

Alcohol abuse has been linked to seizures in adults, although the reason for this is not well established. Theories that may explain the link include a seizure-inducing effect of alcohol, an exacerbation of preexisting epilepsy or the presence of structural abnormalities in the brain related to chronic alcohol intake. Phenytoin is not effective in preventing the recurrence of these seizures, but benzodiazepines have been shown to be effective in the management of acute alcohol syndromes, including the primary prevention of seizures. D'Onofrio and colleagues conducted a randomized, double-blind trial to evaluate the use of lorazepam to prevent recurrent alcohol-related seizures in patients who initially present with a seizure.

Patients enrolled in the trial were adults with a known history of alcohol abuse. They presented to one of two urban emergency departments after having a witnessed generalized seizure and had consumed one or more drinks in the previous 72 hours. An alcohol-related seizure was diagnosed on the basis of a history of alcohol use, no history of recent trauma and review of the patient's medical record. Patients were excluded from the trial if they were found to have another possible cause for the seizures, including hyponatremia, hypoglycemia, hypocalcemia or hypomagnesemia. Patients who were found to have used cocaine or phenobarbital were also excluded because of the anticonvulsant effect of these agents. Patients had computed tomographic scans of the head and an electroencephalogram, if clinically indicated.

Patients who were eligible to participate in the trial were randomly assigned to receive either 2 mg of lorazepam in 2 mL of saline or 4 mL of saline intravenously. The patients and all care providers were unaware of the treatment assignments. In addition, all patients were given fluids, 100 mg of thiamine, 2 g of magnesium and 1 ampule of intravenous multivitamins. The observation period ended if a second seizure occurred in the emergency department or six hours after lorazepam or placebo was administered.

Initially, 229 patients were enrolled, 43 of whom were excluded on the basis of established criteria. Almost all of the patients were men, and the average age was 45 years in the lorazepam group and 44 years in the placebo group. Researchers found that 85 percent of the patients drank at least one pint of distilled alcohol per day for more than 10 years and that 90 percent had the first seizure seven to 48 hours after their last drink. One hundred patients received lorazepam and 86 patients were given placebo.

Twenty-four percent of patients in the placebo group had a second seizure compared with 3 percent in the lorazepam group. When additional patients were excluded after enrollment, the percentages remained essentially the same-27 percent of the patients taking placebo had a second seizure compared with 3 percent of patients taking lorazepam. Thirty-six patients in the placebo group and 29 patients in the lorazepam group were admitted to the hospital. Researchers were able to determine readmission to the emergency department (within 48 hours after discharge) with a seizure by reviewing ambulance records. Seven patients from the placebo group and one patient from the lorazepam group were readmitted, although in the case of the latter patient, it happened only 2.5 hours after discharge.

The authors conclude that lorazepam is safe and effective in preventing recurrent alcohol-related seizures. It may also decrease the number of hospitalizations after a second observed alcohol-related seizure. This is significant, as many hospitals require admission of a patient who has had a second seizure. The study also used logistic-regression analysis to determine if there were any independent predictors for recurrent seizures. The authors found no statistically significant association with age, sex, serum ethanol level, number of years of alcohol use or time since the last drink.

Jeffrey T. Kirchner, D.O.

D'Onofrio G, et al. Lorazepam for the prevention of recurrent seizures related to alcohol. N Engl J Med March 25, 1999;340:915-9.

COPYRIGHT 1999 American Academy of Family Physicians
COPYRIGHT 2000 Gale Group

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