Risks from Concomitant Use with Opioids
Concomitant use of benzodiazepines, including Lorazepam injection, and opioids may result in profound sedation, respiratory depression, coma, and death. If a decision is made to use Lorazepam injection concomitantly with opioids, monitor patients closely for respiratory depression and sedation (see PRECAUTIONS, Drug Interactions).
Abuse, Misuse, and Addiction
The use of benzodiazepines, including Lorazepam injection, exposes users to the risks of abuse, misuse, and addiction, which can lead to overdose or death. Abuse and misuse of benzodiazepines often (but not always) involve the use of doses greater than the maximum recommended dosage and commonly involve concomitant use of other medications, alcohol, and/or illicit substances, which is associated with an increased frequency of serious adverse outcomes, including respiratory depression, overdose, or death (see DRUG ABUSE AND DEPENDENCE, Abuse).
Before prescribing Lorazepam injection and throughout treatment, assess each patient's risk for abuse, misuse, and addiction. Use of Lorazepam injection, particularly in patients at elevated risk, necessitates counseling about the risks and proper use of Lorazepam injection along with monitoring for signs and symptoms of abuse, misuse, and addiction. Do not exceed the recommended dosing frequency; avoid or minimize concomitant use of CNS depressants and other substances associated with abuse, misuse, and addiction (e.g., opioid analgesics, stimulants); and advise patients on the proper disposal of unused drug. If a substance use disorder is suspected, evaluate the patient and institute (or refer them for) early treatment, as appropriate.
Dependence and Withdrawal Reactions After Use of Lorazepam Injection More Frequently Than Recommended
For patients using Lorazepam injection more frequently than recommended, to reduce the risk of withdrawal reactions, use a gradual taper to discontinue Lorazepam injection (a patient-specific plan should be used to taper the dose).
Patients at an increased risk of withdrawal adverse reactions after benzodiazepine discontinuation or rapid dosage reduction include those who take higher dosages, and those who have had longer durations of use.
Acute Withdrawal Reactions
The continued use of benzodiazepines may lead to clinically significant physical dependence. Although Lorazepam injection is indicated only for intermittent use (see INDICATIONS AND USAGE and DOSAGE AND ADMINISTRATION), if used more frequently than recommended, abrupt discontinuation or rapid dosage reduction of Lorazepam injection, or administration of flumazenil (a benzodiazepine antagonist) may precipitate acute withdrawal reactions, which can be life-threatening (e.g., seizures) (see DRUG ABUSE AND DEPENDENCE, Dependence).
Protracted Withdrawal Syndrome
In some cases, benzodiazepine users have developed a protracted withdrawal syndrome with withdrawal symptoms lasting weeks to more than 12 months (see DRUG ABUSE AND DEPENDENCE, Dependence).
Use in Status Epilepticus
Management of Status Epilepticus
Status epilepticus is a potentially life-threatening condition associated with a high risk of permanent neurological impairment, if inadequately treated. The treatment of status, however, requires far more than the administration of an anticonvulsant agent. It involves observation and management of all parameters critical to maintaining vital function and the capacity to provide support of those functions as required. Ventilatory support must be readily available. The use of benzodiazepines, like Lorazepam injection, is ordinarily only one step of a complex and sustained intervention which may require additional interventions (e.g., concomitant intravenous administration of phenytoin). Because status epilepticus may result from a correctable acute cause such as hypoglycemia, hyponatremia, or other metabolic or toxic derangement, such an abnormality must be immediately sought and corrected. Furthermore, patients who are susceptible to further seizure episodes should receive adequate maintenance antiepileptic therapy.
Any healthcare professional who intends to treat a patient with status epilepticus should be familiar with this package insert and the pertinent medical literature concerning current concepts for the treatment of status epilepticus. A comprehensive review of the considerations critical to the informed and prudent management of status epilepticus cannot be provided in drug product labeling. The archival medical literature contains many informative references on the management of status epilepticus, among them the report of the working group on status epilepticus of the Epilepsy Foundation of America "Treatment of Convulsive Status Epilepticus" (JAMA 1993; 270:854–859). As noted in the report just cited, it may be useful to consult with a neurologist if a patient fails to respond (e.g., fails to regain consciousness).
For the treatment of status epilepticus, the usual recommended dose of Lorazepam injection is 4 mg given slowly (2 mg/min) for patients 18 years and older. If seizures cease, no additional Lorazepam injection is required. If seizures continue or recur after a 10- to 15-minute observation period, an additional 4 mg intravenous dose may be slowly administered. Experience with further doses of lorazepam is very limited. The usual precautions in treating status epilepticus should be employed. An intravenous infusion should be started, vital signs should be monitored, an unobstructed airway should be maintained, and artificial ventilation equipment should be available.
The most important risk associated with the use of Lorazepam injection in status epilepticus is respiratory depression. Accordingly, airway patency must be assured and respiration monitored closely. Ventilatory support should be given as required.
AIRWAY OBSTRUCTION MAY OCCUR IN HEAVILY SEDATED PATIENTS. INTRAVENOUS LORAZEPAM AT ANY DOSE, WHEN GIVEN EITHER ALONE OR IN COMBINATION WITH OTHER DRUGS ADMINISTERED DURING ANESTHESIA, MAY PRODUCE HEAVY SEDATION; THEREFORE, EQUIPMENT NECESSARY TO MAINTAIN A PATENT AIRWAY AND TO SUPPORT RESPIRATION/VENTILATION SHOULD BE AVAILABLE.
As is true of similar CNS-acting drugs, the decision as to when patients who have received injectable lorazepam, particularly on an outpatient basis, may again operate machinery, drive a motor vehicle, or engage in hazardous or other activities requiring attention and coordination must be individualized. It is recommended that no patient engage in such activities for a period of 24 to 48 hours or until the effects of the drug, such as drowsiness, have subsided, whichever is longer. Impairment of performance may persist for greater intervals because of extremes of age, concomitant use of other drugs, stress of surgery, or the general condition of the patient.
Clinical trials have shown that patients over the age of 50 years may have a more profound and prolonged sedation with intravenous lorazepam (see DOSAGE AND ADMINISTRATION, Preanesthetic).
As with all central-nervous-system-depressant drugs, care should be exercised in patients given injectable lorazepam as premature ambulation may result in injury from falling.
There is no added beneficial effect from the addition of scopolamine to injectable lorazepam, and their combined effect may result in an increased incidence of sedation, hallucination and irrational behavior.
General (All Uses)
PRIOR TO INTRAVENOUS USE, LORAZEPAM INJECTION MUST BE DILUTED WITH AN EQUAL AMOUNT OF COMPATIBLE DILUENT (see DOSAGE AND ADMINISTRATION). INTRAVENOUS INJECTION SHOULD BE MADE SLOWLY AND WITH REPEATED ASPIRATION. CARE SHOULD BE TAKEN TO DETERMINE THAT ANY INJECTION WILL NOT BE INTRA-ARTERIAL AND THAT PERIVASCULAR EXTRAVASATION WILL NOT TAKE PLACE. IN THE EVENT THAT A PATIENT COMPLAINS OF PAIN DURING INTENDED INTRAVENOUS INJECTION OF LORAZEPAM INJECTION, THE INJECTION SHOULD BE STOPPED IMMEDIATELY TO DETERMINE IF INTRA-ARTERIAL INJECTION OR PERIVASCULAR EXTRAVASATION HAS TAKEN PLACE.
Since the liver is the most likely site of conjugation of lorazepam and since excretion of conjugated lorazepam (glucuronide) is a renal function, this drug is not recommended for use in patients with hepatic and/or renal failure. Lorazepam should be used with caution in patients with mild-to-moderate hepatic or renal disease (see DOSAGE AND ADMINISTRATION).
LORAZEPAM MAY CAUSE FETAL DAMAGE WHEN ADMINISTERED TO PREGNANT WOMEN. Ordinarily, Lorazepam injection should not be used during pregnancy except in serious or life-threatening conditions where safer drugs cannot be used or are ineffective. Status epilepticus may represent such a serious and life-threatening condition.
An increased risk of congenital malformations associated with the use of minor tranquilizers (chlordiazepoxide, diazepam and meprobamate) during the first trimester of pregnancy has been suggested in several studies. In humans, blood levels obtained from umbilical cord blood indicate placental transfer of lorazepam and lorazepam glucuronide.
Reproductive studies in animals were performed in mice, rats, and two strains of rabbits. Occasional anomalies (reduction of tarsals, tibia, metatarsals, malrotated limbs, gastroschisis, malformed skull, and microphthalmia) were seen in drug-treated rabbits without relationship to dosage. Although all of these anomalies were not present in the concurrent control group, they have been reported to occur randomly in historical controls. At doses of 40 mg/kg orally or 4 mg/kg intravenously and higher, there was evidence of fetal resorption and increased fetal loss in rabbits which was not seen at lower doses.
The possibility that a woman of childbearing potential may be pregnant at the time of therapy should be considered.
There are insufficient data regarding obstetrical safety of parenteral lorazepam, including use in cesarean section. Such use, therefore, is not recommended.
Usage in Preterm Infants and Neonates
Lorazepam injection contains benzyl alcohol. Exposure to excessive amounts of benzyl alcohol has been associated with toxicity (hypotension, metabolic acidosis), particularly in neonates, and an increased incidence of kernicterus, particularly in small preterm infants. There have been rare reports of deaths, primarily in preterm infants, associated with exposure to excessive amounts of benzyl alcohol. The amount of benzyl alcohol from medications is usually considered negligible compared to that received in flush solutions containing benzyl alcohol. Administration of high dosages of medications (including Lorazepam) containing this preservative must take into account the total amount of benzyl alcohol administered. The recommended dosage range of Lorazepam for preterm and term infants includes amounts of benzyl alcohol well below that associated with toxicity; however, the amount of benzyl alcohol at which toxicity may occur is not known. If the patient requires more than the recommended dosages or other medications containing this preservative, the practitioner must consider the daily metabolic load of benzyl alcohol from these combined sources (see WARNINGS and PRECAUTIONS, Pediatric Use).
Published animal studies demonstrate that the administration of anesthetic and sedation drugs that block NMDA receptors and/or potentiate GABA activity increase neuronal apoptosis in the developing brain and result in long-term cognitive deficits when used for longer than 3 hours. The clinical significance of these findings is not clear. However, based on the available data, 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 three years of age in humans (see PRECAUTIONS, Pregnancy, Pediatric Use; ANIMAL TOXICOLOGY AND/OR PHARMACOLOGY).
Some published studies in children suggest that similar deficits may occur after repeated or prolonged exposures to anesthetic agents early in life and may result in adverse cognitive or behavioral effects. These studies have substantial limitations, and it is not clear if the observed effects are due to the anesthetic/sedation drug administration or other factors such as the surgery or underlying illness.
Anesthetic and sedation drugs are a necessary part of the care of children needing surgery, other procedures, or tests that cannot be delayed, and no specific medications have been shown to be safer than any other. Decisions regarding the timing of any elective procedures requiring anesthesia should take into consideration the benefits of the procedure weighed against the potential risks.
There are insufficient data to support the use of lorazepam injection for outpatient endoscopic procedures. Inpatient endoscopic procedures require adequate recovery room observation time.
When lorazepam injection is used for peroral endoscopic procedures, adequate topical or regional anesthesia is recommended to minimize reflex activity associated with such procedures.
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 intravenous 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.
Information for Patients
Risks From Concomitant Use With Opioids
Concomitant use of benzodiazepines, including Lorazepam injection, and opioids may result in profound sedation, respiratory depression, coma, and death (see WARNINGS and PRECAUTIONS, Drug Interactions).
Abuse, Misuse, and Addiction
Inform patients that the use of Lorazepam injection more frequently than recommended, even at recommended dosages, exposes users to risks of abuse, misuse, and addiction, which can lead to overdose and death, especially when used in combination with other medications (e.g., opioid analgesics), alcohol, and/or illicit substances. Inform patients about the signs and symptoms of benzodiazepine abuse, misuse, and addiction; to seek medical help if they develop these signs and/or symptoms; and on the proper disposal of unused drug (see WARNINGS and DRUG ABUSE AND DEPENDENCE).
Inform patients that use of Lorazepam injection more frequently than recommended may lead to clinically significant physical dependence and that abrupt discontinuation or rapid dosage reduction of Lorazepam injection may precipitate acute withdrawal reactions, which can be life-threatening. Inform patients that in some cases, patients taking benzodiazepines have developed a protracted withdrawal syndrome with withdrawal symptoms lasting weeks to more than 12 months (see WARNINGS and DRUG ABUSE AND DEPENDENCE).
Patients should be informed of the pharmacological effects of the drug, including sedation, relief of anxiety, and lack of recall, the duration of these effects (about 8 hours), and be apprised of the risks as well as the benefits of therapy.
Patients who receive lorazepam injection as a premedicant should be cautioned that driving a motor vehicle, operating machinery, or engaging in hazardous or other activities requiring attention and coordination, should be delayed for 24 to 48 hours following the injection or until the effects of the drug, such as drowsiness, have subsided, whichever is longer. Sedatives, tranquilizers and narcotic analgesics may produce a more prolonged and profound effect when administered along with injectable lorazepam. This effect may take the form of excessive sleepiness or drowsiness and, on rare occasions, interfere with recall and recognition of events of the day of surgery and the day after.
Patients should be advised that getting out of bed unassisted may result in falling and injury if undertaken within 8 hours of receiving lorazepam injection. Since tolerance for CNS depressants will be diminished in the presence of lorazepam injection, these substances should either be avoided or taken in reduced dosage. Alcoholic beverages should not be consumed for at least 24 to 48 hours after receiving lorazepam injectable due to the additive effects on central-nervous-system depression seen with benzodiazepines in general. Elderly patients should be told that lorazepam injection may make them very sleepy for a period longer than 6 to 8 hours following surgery.
Effect of Anesthetic and Sedation Drugs on Early Brain Development
Studies conducted in young animals and children suggest repeated or prolonged use of general anesthetic or sedation drugs in children younger than 3 years may have negative effects on their developing brains. Discuss with parents and caregivers the benefits, risks, and timing and duration of surgery or procedures requiring anesthetic and sedation drugs (see WARNINGS, Pediatric Neurotoxicity).
In clinical trials, no laboratory test abnormalities were identified with either single or multiple doses of lorazepam injection. These tests included: CBC, urinalysis, SGOT, SGPT, bilirubin, alkaline phosphatase, LDH, cholesterol, uric acid, BUN, glucose, calcium, phosphorus, and total proteins.
Interaction With Benzodiazepines and Other CNS Depressants
The concomitant use of benzodiazepines and opioids increases the risk of respiratory depression because of actions at different receptor sites in the CNS that control respiration. Benzodiazepines interact at GABAA sites and opioids interact primarily at mu receptors. When benzodiazepines and opioids are combined, the potential for benzodiazepines to significantly worsen opioid-related respiratory depression exists. Monitor patients closely for respiratory depression and sedation.
Lorazepam injection, like other injectable benzodiazepines, produces additive depression of the central nervous system when administered with other CNS depressants such as 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 behavior has been observed.
There have been rare reports of significant respiratory depression, stupor and/or hypotension with the concomitant use of loxapine and lorazepam.
Marked sedation, excessive salivation, ataxia, and, rarely, death have been reported with the concomitant use of clozapine and lorazepam.
Apnea, coma, bradycardia, arrhythmia, heart arrest, and death have been reported with the concomitant use of haloperidol and lorazepam.
The risk of using lorazepam in combination with scopolamine, loxapine, clozapine, haloperidol, or other CNS-depressant drugs has not been systematically evaluated. Therefore, caution is advised if the concomitant administration of lorazepam and these drugs is required.
Concurrent administration of any of the following drugs with lorazepam had no effect on the pharmacokinetics of lorazepam: metoprolol, cimetidine, ranitidine, disulfiram, propranolol, metronidazole, and propoxyphene. No change in lorazepam dosage is necessary when concomitantly given with any of these drugs.
Concurrent administration of lorazepam (2 mg intravenously) with valproate (250 mg twice daily orally for 3 days) to 6 healthy male subjects resulted in decreased total clearance of lorazepam by 40% and decreased formation rate of lorazepam glucuronide by 55%, as compared with lorazepam administered alone. Accordingly, lorazepam plasma concentrations were about two-fold higher for at least 12 hours post-dose administration during valproate treatment. Lorazepam dosage should be reduced to 50% of the normal adult dose when this drug combination is prescribed in patients (see DOSAGE AND ADMINISTRATION).
Lorazepam-Oral Contraceptive Steroids Interaction
Coadministration of lorazepam (2 mg intravenously) with oral contraceptive steroids (norethindrone acetate, 1 mg, and ethinyl estradiol, 50 mcg, for at least 6 months) to healthy females (n=7) was associated with a 55% decrease in half-life, a 50% increase in the volume of distribution, thereby resulting in an almost 3.7-fold increase in total clearance of lorazepam as compared with control healthy females (n=8). It may be necessary to increase the dose of lorazepam in female patients who are concomitantly taking oral contraceptives (see DOSAGE AND ADMINISTRATION).
Concurrent administration of lorazepam (2 mg intravenously) with probenecid (500 mg orally every 6 hours) to 9 healthy volunteers resulted in a prolongation of lorazepam half-life by 130% and a decrease in its total clearance by 45%. No change in volume of distribution was noted during probenecid co-treatment. Lorazepam dosage needs to be reduced by 50% when coadministered with probenecid (see DOSAGE AND ADMINISTRATION).
Drug/Laboratory Test Interactions
No laboratory test abnormalities were identified when lorazepam was given alone or concomitantly with another drug, such as narcotic analgesics, inhalation anesthetics, scopolamine, atropine, and a variety of tranquilizing agents.
Carcinogenesis, Mutagenesis, Impairment of Fertility
No evidence of carcinogenic potential emerged in rats and mice during an 18-month study with oral lorazepam. No studies regarding mutagenesis have been performed. The results of a preimplantation study in rats, in which the oral lorazepam dose was 20 mg/kg, showed no impairment of fertility.
Published studies in pregnant primates demonstrate that the administration of anesthetic and sedation drugs that block NMDA receptors and/or potentiate GABA activity during the period of peak brain development increases neuronal apoptosis in the developing brain of the offspring when used for longer than 3 hours.
There are no data on pregnancy exposures in primates corresponding to periods prior to the third trimester in humans.
In a published study in primates, administration of an anesthetic dose of ketamine for 24 hours on Gestation Day 122 increased neuronal apoptosis in the developing brain of the fetus. In other published studies, administration of either isoflurane or propofol for 5 hours on Gestation Day 120 resulted in increased neuronal and oligodendrocyte apoptosis in the developing brain of the offspring. With respect to brain development, this time period corresponds to the third trimester of gestation in the human. The clinical significance of these findings is not clear; however, studies in juvenile animals suggest neuroapoptosis correlates with long-term cognitive deficits (see WARNINGS, Pediatric Neurotoxicity, Pediatric Use, and ANIMAL TOXICOLOGY AND/OR PHARMACOLOGY).
Labor and Delivery
There are insufficient data to support the use of lorazepam injection during labor and delivery, including cesarean section; therefore, its use in this clinical circumstance is not recommended.
Lorazepam has been detected in human breast milk. Therefore, lorazepam should not be administered to nursing mothers because, like other benzodiazepines, the possibility exists that lorazepam may sedate or otherwise adversely affect the infant.
The safety and effectiveness of lorazepam for status epilepticus have not been established in pediatric patients. A randomized, double-blind, superiority-design clinical trial of lorazepam versus intravenous diazepam in 273 pediatric patients ages 3 months to 17 years failed to establish the efficacy of lorazepam for the treatment of status epilepticus. In that trial, assisted ventilation was required in 18% of patients treated with lorazepam versus 16% of patients treated with diazepam. Patients treated with lorazepam were also more likely to be reported as sedated (67% for lorazepam vs. 50% for diazepam), and the time for return to baseline mental status was, on average, 2 hours longer for lorazepam than for diazepam.
Open-label studies described in the medical literature included 273 pediatric patients; the age range was from a few hours old to 18 years of age. Paradoxical excitation was observed in 10% to 30% of the pediatric patients under 8 years of age and was characterized by tremors, agitation, euphoria, logorrhea, and brief episodes of visual hallucinations. Paradoxical excitation in pediatric patients also has been reported with other benzodiazepines when used for status epilepticus, as an anesthesia, or for pre-chemotherapy treatment.
Pediatric patients (as well as adults) with atypical petit mal status epilepticus have developed brief tonic-clonic seizures shortly after lorazepam was given. This "paradoxical" effect was also reported for diazepam and clonazepam. Nevertheless, the development of seizures after treatment with benzodiazepines is probably rare, based on the incidence in the uncontrolled treatment series reported (i.e., seizures were not observed for 112 pediatric patients and 18 adults or during approximately 400 doses).
Lorazepam injection contains benzyl alcohol as a preservative. Benzyl alcohol, a component of this product, has been associated with serious adverse events and death, particularly in pediatric patients. 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 benzyl alcohol dosages greater than 99 mg/kg/day in neonates and low-birth-weight neonates. Additional symptoms may include gradual neurological deterioration, seizures, intracranial hemorrhage, hematologic abnormalities, skin breakdown, hepatic and renal failure, hypotension, bradycardia, and cardiovascular collapse. Although normal therapeutic doses of this product deliver amounts of benzyl alcohol that are substantially lower than those reported in association with the "gasping syndrome", the minimum amount of benzyl alcohol at which toxicity may occur is not known. Premature and low-birth-weight infants, as well as patients receiving high dosages, may be more likely to develop toxicity. Practitioners administering this and other medications containing benzyl alcohol should consider the combined daily metabolic load of benzyl alcohol from all sources.
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 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).
Clinical studies of lorazepam generally were not adequate to determine whether subjects aged 65 and over respond differently than younger subjects; however, age over 65 may be associated with a greater incidence of central nervous system depression and more respiratory depression (see WARNINGS, Preanesthetic Use, PRECAUTIONS, General and ADVERSE REACTIONS, Preanesthetic). Age does not appear to have a clinically significant effect on lorazepam kinetics (see CLINICAL PHARMACOLOGY).
Clinical circumstances, some of which may be more common in the elderly, such as hepatic or renal impairment, should be considered. Greater sensitivity (e.g., sedation) of some older individuals cannot be ruled out. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range (see DOSAGE AND ADMINISTRATION).