Amidate

INDICATIONS AND USAGE AMIDATE is indicated by intravenous injection for the induction of general anesthesia. When considering use of AMIDATE, the usefulness of its hemodynamic properties (see CLINICAL PHARMACOLOGY ) should be weighed against the high frequency of transient skeletal muscle movements (see ADVERSE REACTIONS ). Intravenous AMIDATE is also indicated for the supplementation of subpotent anesthetic agents, such as nitrous oxide in oxygen, during maintenance of anesthesia for short operative procedures such as dilation and curettage or cervical conization.

DOSAGE AND ADMINISTRATION Do not administer unless solution is clear and container is undamaged. Discard unused portion (see DOSAGE AND ADMINISTRATION ). AMIDATE is intended for administration only by the intravenous route (see CLINICAL PHARMACOLOGY ). The dose for induction of anesthesia in adult patients and in pediatric patients above the age of ten (10) years will vary between 0.2 mg/kg and 0.6 mg/kg of body weight, and it must be individualized in each case. The usual dose for induction in these patients is 0.3 mg/kg, injected over a period of 30 to 60 seconds. There are inadequate data to make dosage recommendations for induction of anesthesia in patients below the age of ten (10) years; therefore, such use is not recommended. Geriatric patients may require reduced doses of etomidate. Smaller increments of intravenous AMIDATE may be administered to adult patients during short operative procedures to supplement subpotent anesthetic agents, such as nitrous oxide. The dosage employed under these circumstances, although usually smaller than the original induction dose, must be individualized. There are insufficient data to support this use of etomidate for longer adult procedures or for any procedures in pediatric patients; therefore, such use is not recommended. The use of intravenous fentanyl and other neuroactive drugs employed during the conduct of anesthesia may alter the etomidate dosage requirements. Consult the prescribing information for all other such drugs before using. Premedication AMIDATE is compatible with commonly administered pre-anesthetic medications, which may be employed as indicated. See also CLINICAL PHARMACOLOGY , ADVERSE REACTIONS , and dosage recommendations for maintenance of anesthesia. AMIDATE anesthesia does not significantly alter the usual dosage requirements of neuromuscular blocking agents employed for endotracheal intubation or other purposes shortly after induction of anesthesia. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. To prevent needle-stick injuries, needles should not be recapped, purposely bent, or broken by hand.

CONTRAINDICATIONS AMIDATE is contraindicated in patients who have shown hypersensitivity to it.

WARNINGS INTRAVENOUS AMIDATE SHOULD BE ADMINISTERED ONLY BY PERSONS TRAINED IN THE ADMINISTRATION OF GENERAL ANESTHETICS AND IN THE MANAGEMENT OF COMPLICATIONS ENCOUNTERED DURING THE CONDUCT OF GENERAL ANESTHESIA. BECAUSE OF THE HAZARDS OF PROLONGED SUPPRESSION OF ENDOGENOUS CORTISOL AND ALDOSTERONE PRODUCTION, THIS FORMULATION IS NOT INTENDED FOR ADMINISTRATION BY PROLONGED INFUSION. Pediatric Neurotoxicity 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 PHARMACOLOGY AND/OR TOXICOLOGY ). 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.

ADVERSE REACTIONS The most frequent adverse reactions associated with use of intravenous AMIDATE are transient venous pain on injection and transient skeletal muscle movements, including myoclonus: 1. Transient venous pain was observed immediately following intravenous injection of etomidate in about 20% of the patients, with considerable difference in the reported incidence (1.2% to 42%). This pain is usually described as mild to moderate in severity but it is occasionally judged disturbing. The observation of venous pain is not associated with a more than usual incidence of thrombosis or thrombophlebitis at the injection site. Pain also appears to be less frequently noted when larger, more proximal arm veins are employed and it appears to be more frequently noted when smaller, more distal, hand or wrist veins are employed. 2. Transient skeletal muscle movements were noted following use of intravenous etomidate in about 32% of the patients, with considerable difference in the reported incidence (22.7% to 63%). Most of these observations were judged mild to moderate in severity but some were judged disturbing. The incidence of disturbing movements was less when 0.1 mg of fentanyl was given immediately before induction. These movements have been classified as myoclonic in the majority of cases (74%), but averting movements (7%), tonic movements (10%), and eye movements (9%) have also been reported. No exact classification is available, but these movements may also be placed into three groups by location: a. Most movements are bilateral. The arms, legs, shoulders, neck, chest wall, trunk and all four extremities have been described in some cases, with one or more of these muscle groups predominating in each individual case. Results of electroencephalographic studies suggest that these muscle movements are a manifestation of disinhibition of cortical activity; cortical electroencephalograms, taken during periods when these muscle movements were observed, have failed to reveal seizure activity. b. Other movements are described as either unilateral or having a predominance of activity of one side over the other. These movements sometimes resemble a localized response to some stimuli, such as venous pain on injection, in the lightly anesthetized patient (averting movements). Any muscle group or groups may be involved, but a predominance of movement of the arm in which the intravenous infusion is started is frequently noted. c. Still other movements probably represent a mixture of the first two types. Skeletal muscle movements appear to be more frequent in patients who also manifest venous pain on injection. Other Adverse Observations Respiratory System Hyperventilation, hypoventilation, apnea of short duration (5 to 90 seconds with spontaneous recovery); laryngospasm, hiccup and snoring suggestive of partial upper airway obstruction have been observed in some patients. These conditions were managed by conventional countermeasures. Circulatory System Hypertension, hypotension, tachycardia, bradycardia and other arrhythmias have occasionally been observed during induction and maintenance of anesthesia. One case of severe hypotension and tachycardia, judged to be anaphylactoid in character, has been reported. Geriatric patients, particularly those with hypertension, may be at increased risk for the development of cardiac depression following etomidate administration (see CLINICAL PHARMACOLOGY ). Gastrointestinal System Postoperative nausea and/or vomiting following induction of anesthesia with etomidate is probably no more frequent than the general incidence. When etomidate was used for both induction and maintenance of anesthesia in short procedures such as dilation and curettage, or when insufficient analgesia was provided, the incidence of postoperative nausea and/or vomiting was higher than that noted in control patients who received thiopental.

Pregnancy Risk Summary There are no adequate and well-controlled studies in pregnant women. In animal reproduction studies, fetal deaths and reduced pup survival were noted after intravenous administration of etomidate to pregnant rats at doses 0.17 times the human induction dose of 0.3 mg/kg. Reduced pup survival was noted after intravenous administration of etomidate to pregnant rabbits at 1.6 times the human induction dose. 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 (see Data ). The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Animal Data No malformations or adverse fetal effects were noted in a study in which pregnant rats were intravenously administered 0.31, 1.25, or 5 mg/kg/day etomidate (0.17, 0.68, or 2.7 times the human induction dose of 0.3 mg/kg based on body surface area) during organogenesis (Gestation Days 6–15). Reduced pup survival was noted in all doses tested in a study in which pregnant rabbits were intravenously administered 1.5 or 4.5 mg/kg/day etomidate (1.6 or 4.9 times the human induction dose of 0.3 mg/kg based on body surface area) during organogenesis (Gestation Day 6–18). These doses also produced maternal toxicity (increased mortality). Increased still born fetuses and decreased pup survival was noted at all doses tested in a study where pregnant rats were intravenously administered 0.31, 1.25, or 5 mg/kg/day etomidate (0.17, 0.68, or 2.7 times the human induction dose of 0.3 mg/kg based on body surface area) during gestation and throughout lactation (Gestation Day 16 through Lactation Day 21). These doses also produced maternal toxicity (decreased food consumption and increased mortality). In this study, offspring were not evaluated for sexual maturation, neurobehavioral function including learning and memory, or reproductive function. 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 , PRECAUTIONS/Pregnancy , ANIMAL TOXICOLOGY AND/OR PHARMACOLOGY ).