The additive central-nervous-system effects of other drugs, such as phenothiazines, narcotic analgesics, barbiturates, antidepressants, scopolamine, and monoamine-oxidase inhibitors, should be borne in mind when these other drugs are used concomitantly with or during the period of recovery from Lorazepam Injection (see CLINICAL PHARMACOLOGY and WARNINGS).
Extreme caution must be used when administering Lorazepam Injection to elderly patients, very ill patients, or to patients with limited pulmonary reserve because of the possibility that hypoventilation and/or hypoxic cardiac arrest may occur. Resuscitative equipment for ventilatory support should be readily available (see WARNINGS and DOSAGE AND ADMINISTRATION).
When lorazepam injection is used IV as the premedicant prior to regional or local anesthesia, the possibility of excessive sleepiness or drowsiness may interfere with patient cooperation in determining levels of anesthesia. This is most likely to occur when greater than 0.05 mg/kg is given and when narcotic analgesics are used concomitantly with the recommended dose (see ADVERSE REACTIONS).
As with all benzodiazepines, paradoxical reactions may occur in rare instances and in an unpredictable fashion (see ADVERSE REACTIONS). In these instances, further use of the drug in these patients should be considered with caution.
There have been reports of possible propylene glycol toxicity (e.g., lactic acidosis, hyperosmolality, hypotension) and possible polyethylene glycol toxicity (e.g., acute tubular necrosis) during administration of Lorazepam Injection at higher than recommended doses. Symptoms may be more likely to develop in patients with renal impairment.
Seizure activity and myoclonus have been reported to occur following administration of Lorazepam Injection, especially in very low birth weight neonates.
Pediatric patients may exhibit a sensitivity to benzyl alcohol, polyethylene glycol and propylene glycol, components of Lorazepam Injection (see also CONTRAINDICATIONS). The “gasping syndrome”, characterized by central nervous system depression, metabolic acidosis, gasping respirations, and high levels of benzyl alcohol and its metabolites found in the blood and urine, has been associated with the administration of intravenous solutions containing the preservative benzyl alcohol in neonates. Additional symptoms may include gradual neurological deterioration, seizures, intracranial hemorrhage, hematologic abnormalities, skin breakdown, hepatic and renal failure, hypotension, bradycardia, and cardiovascular collapse. Central nervous system toxicity, including seizures and intraventricular hemorrhage, as well as unresponsiveness, tachypnea, tachycardia, and diaphoresis have been associated with propylene glycol toxicity. Although normal therapeutic doses of Lorazepam Injection contain very small amounts of these compounds, premature and low-birth-weight infants as well as pediatric patients receiving high doses may be more susceptible to their effects.
Published juvenile animal studies demonstrate that the administration of anesthetic and sedation drugs, such as lorazepam that either block NMDA receptors or potentiate the activity of GABA during the period of rapid brain growth or synaptogenesis, results in widespread neuronal and oligodendrocyte cell loss in the developing brain and alterations in synaptic morphology and neurogenesis. Based on comparisons across species, the window of vulnerability to these changes is believed to correlate with exposures in the third trimester of gestation through the first several months of life, but may extend out to approximately 3 years of age in humans.
In primates, exposure to 3 hours of ketamine that produced a light surgical plane of anesthesia did not increase neuronal cell loss, however, treatment regimens of 5 hours or longer of isoflurane increased neuronal cell loss. Data from isoflurane-treated rodents and ketamine-treated primates suggest that the neuronal and oligodendrocyte cell losses are associated with prolonged cognitive deficits in learning and memory. The clinical significance of these nonclinical findings is not known, and healthcare providers should balance the benefits of appropriate anesthesia in pregnant women, neonates and young children who require procedures with the potential risks suggested by the nonclinical data. (See WARNINGS, Pediatric Neurotoxicity; PRECAUTIONS, Pregnancy; ANIMAL TOXICOLOGY AND/OR PHARMACOLOGY).