If lorazepam is to be used together with other drugs acting on the CNS, careful consideration should be given to the pharmacology of the agents to be employed because of the possible potentiation of drug effects. The benzodiazepines, including Ativan (lorazepam), produce additive CNS depressant effects, when administered with other CNS depressants such as barbiturates, antipsychotics, sedative/hypnotics, anxiolytics, antidepressants, narcotic analgesics, sedative antihistamines, anticonvulsants, anesthetics and alcohol.
Due to additive CNS depressant effect, the concomitant use of benzodiazepines, including ATIVAN, and opioids increases the risk of profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing of these drugs for use in patients for whom alternative treatment options are inadequate. Limit dosages and durations of concomitant use of benzodiazepines and opioids to the minimum required. Follow patients closely for respiratory depression and sedation (see WARNINGS - Risks from concomitant use of opioids and benzodiazepines).
There have been reports of apnea, coma, bradycardia, heart arrest, and death with the concomitant use of lorazepam injection and haloperidol.
Concomitant use of clozapine and lorazepam may produce marked sedation, excessive salivation, and ataxia.
Concurrent administration of lorazepam with valproate may result in increased plasma concentrations and reduced clearance of lorazepam. Lorazepam dosage should be reduced to approximately 50% when co-administered with valproate.
Concurrent administration of lorazepam with probenecid may result in a more rapid onset or prolonged effect of lorazepam due to increased half-life and decreased total clearance.
Lorazepam dosage needs to be reduced by approximately 50% when co-administered with probenecid.
Administration of theophylline or aminophylline may reduce the sedative effects of benzodiazepines, including lorazepam.
Ativan (lorazepam) produces depression of the CNS when administered with ethyl alcohol, phenothiazines, barbiturates, MAO inhibitors and other antidepressants. When scopolamine is used concomitantly with injectable lorazepam, an increased incidence of sedation, hallucinations and irrational behaviour has been observed.