Atracurium Besylate Drug Information

Atracurium Besylate Injection, USP is indicated, as an adjunct to general anesthesia, to facilitate endotracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical ventilation.

To avoid distress to the patient, atracurium should not be administered before unconsciousness has been induced. Atracurium should not be mixed in the same syringe, or administered simultaneously through the same needle, with alkaline solutions (e.g., barbiturate solutions). Atracurium besylate should be administered intravenously.

DO NOT GIVE ATRACURIUM BESYLATE BY INTRAMUSCULAR ADMINISTRATION. Intramuscular administration of atracurium besylate may result in tissue irritation and there are no clinical data to support this route of administration. As with other neuromuscular blocking agents, the use of a peripheral nerve stimulator will permit the most advantageous use of atracurium besylate, minimizing the possibility of overdosage or underdosage, and assist in the evaluation of recovery.

Clinically required neuromuscular block generally lasts 20 to 35 minutes under balanced anesthesia. Atracurium is potentiated by isoflurane or enflurane anesthesia. The same initial atracurium besylate dose of 0.4 to 0.5 mg/kg may be used for intubation prior to administration of these inhalation agents; however, if atracurium is first administered under steady-state of isoflurane or enflurane, the initial atracurium besylate dose should be reduced by approximately one-third, i.e., to 0.25 to 0.35 mg/kg, to adjust for the potentiating effects of these anesthetic agents.

With halothane, which has only a marginal (approximately 20%) potentiating effect on atracurium, smaller dosage reductions may be considered. Atracurium besylate doses of 0.08 to 0.1 mg/kg are recommended for maintenance of neuromuscular block during prolonged surgical procedures. The first maintenance dose will generally be required 20 to 45 minutes after the initial atracurium besylate injection, but the need for maintenance doses should be determined by clinical criteria.

Because atracurium lacks cumulative effects, maintenance doses may be administered at relatively regular intervals for each patient, ranging approximately from 15 to 25 minutes under balanced anesthesia, slightly longer under isoflurane or enflurane. Higher atracurium doses (up to 0.2 mg/kg) permit maintenance dosing at longer intervals. Pediatric Patients No atracurium dosage adjustments are required for pediatric patients two years of age or older.

Maintenance doses may be required with slightly greater frequency in infants and children than in adults. Special Considerations An initial atracurium besylate dose of 0.3 to 0.4 mg/kg, given slowly or in divided doses over one minute, is recommended for adults, children, or infants with significant cardiovascular disease and for adults, children, or infants with any history (e.g., severe anaphylactoid reactions or asthma) suggesting a greater risk of histamine release. Dosage reductions must be considered also in patients with neuromuscular disease, severe electrolyte disorders, or carcinomatosis in which potentiation of neuromuscular block or difficulties with reversal have been demonstrated.

There has been no clinical experience with atracurium in these patients, and no specific dosage adjustments can be recommended. No atracurium dosage adjustments are required for patients with renal disease. An initial atracurium besylate dose of 0.3 to 0.4 mg/kg is recommended for adults following the use of succinylcholine for intubation under balanced anesthesia.

Further reductions may be desirable with the use of potent inhalation anesthetics. The patient should be permitted to recover from the effects of succinylcholine prior to atracurium administration. Insufficient data are available for recommendation of a specific initial atracurium dose for administration following the use of succinylcholine in children and infants.

Use by Continuous Infusion Infusion in the Operating Room (OR) After administration of a recommended initial bolus dose of atracurium besylate injection (0.3 to 0.5 mg/kg), a diluted solution of atracurium besylate can be administered by continuous infusion to adults and pediatric patients aged 2 or more years for maintenance of neuromuscular block during extended surgical procedures. Infusion of atracurium should be individualized for each patient. The rate of administration should be adjusted according to the patient’s response as determined by peripheral nerve stimulation.

Accurate dosing is best achieved using a precision infusion device. Infusion of atracurium should be initiated only after early evidence of spontaneous recovery from the bolus dose. An initial infusion rate of 9 to 10 mcg/kg/min may be required to rapidly counteract the spontaneous recovery of neuromuscular function.

Occasional patients may require infusion rates as low as 2 mcg/kg/min or as high as 15 mcg/kg/min. The neuromuscular blocking effect of atracurium administered by infusion is potentiated by enflurane or isoflurane and, to a lesser extent, by halothane. Reduction in the infusion rate of atracurium should, therefore, be considered for patients receiving inhalation anesthesia.

The rate of atracurium infusion should be reduced by approximately one-third in the presence of steady-state enflurane or isoflurane anesthesia; smaller reductions should be considered in the presence of halothane. In patients undergoing cardiopulmonary bypass with induced hypothermia, the rate of infusion of atracurium required to maintain adequate surgical relaxation during hypothermia (25° to 28°C) has been shown to be approximately half the rate required during normothermia. Spontaneous recovery from neuromuscular block following discontinuation of atracurium infusion may be expected to proceed at a rate comparable to that following administration of a single bolus dose.

Infusion in the Intensive Care Unit (ICU) The principles for infusion of atracurium in the OR are also applicable to use in the ICU. Limited information suggests that infusion rates required for pediatric patients in the ICU may be higher than in adult patients. There may be wide interpatient variability in dosage requirements and these requirements may increase or decrease with time (see PRECAUTIONS: Long-Term Use in Intensive Care Unit (ICU) ).

Following recovery from neuromuscular block, readministration of a bolus dose may be necessary to quickly re-establish neuromuscular block prior to reinstitution of the infusion. Infusion Rate Tables The amount of infusion solution required per minute will depend upon the concentration of atracurium in the infusion solution, the desired dose of atracurium, and the patient’s weight. Infusion solutions should be used within 24 hours of preparation.

Unused solutions should be discarded. Solutions containing 0.2 mg/mL or 0.5 mg/mL atracurium besylate in the above diluents may be stored either under refrigeration or at room temperature for 24 hours without significant loss of potency. Care should be taken during admixture to prevent inadvertent contamination.

Visually inspect prior to administration. Spontaneous degradation of atracurium besylate has been demonstrated to occur more rapidly in Lactated Ringer’s solution than in 0.9% sodium chloride solution. Therefore, it is recommended that Lactated Ringer’s Injection not be used as a diluent in preparing solutions of atracurium besylate injection for infusion.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Risk of Medication Errors: Accidental administration of neuromuscular blocking agents may be fatal. Store atracurium besylate injection with the cap and ferrule intact and in a manner that minimizes the possibility of selecting the wrong product.

Observed in Controlled Clinical Studies Atracurium was well tolerated and produced few adverse reactions during extensive clinical trials. Most adverse reactions were suggestive of histamine release. In studies including 875 patients, atracurium was discontinued in only one patient (who required treatment for bronchial secretions) and six other patients required treatment for adverse reactions attributable to atracurium (wheezing in one, hypotension in five).

Of the five patients who required treatment for hypotension, three had a history of significant cardiovascular disease. The overall incidence rate for clinically important adverse reactions, therefore, was 7/875 or 0.8%. Table 1 includes all adverse reactions reported attributable to atracurium during clinical trials with 875 patients.

Table 1: Percent of Patients Reporting Most adverse reactions were of little clinical significance unless they were associated with significant hemodynamic changes. Table 2 summarizes the incidences of substantial vital sign changes noted during atracurium clinical trials with 530 patients, without cardiovascular disease, in whom these parameters were assessed. Table 2: Percent of Patients Showing >30% Vital Sign Changes Following Administration of Atracurium Observed in Clinical Practice Based on initial clinical practice experience in approximately 3 million patients who received atracurium in the U.S. and in the United Kingdom, spontaneously reported adverse reactions were uncommon (approximately 0.01% to 0.02%).

The following adverse reactions are among the most frequently reported, but there are insufficient data to support an estimate of their incidence: General: Allergic reactions (anaphylactic or anaphylactoid responses) which, in rare instances, were severe (e.g., cardiac arrest) Musculoskeletal: Inadequate block, prolonged block Cardiovascular: Hypotension, vasodilatation (flushing), tachycardia, bradycardia Respiratory: Dyspnea, bronchospasm, laryngospasm Integumentary: Rash, urticaria, reaction at injection site There have been rare spontaneous reports of seizures in ICU patients following long-term infusion of atracurium to support mechanical ventilation. There are insufficient data to define the contribution, if any, of atracurium and/or its metabolite laudanosine. (See PRECAUTIONS: Long-Term Use in Intensive Care Unit (ICU) ). There have been post-marketing reports of severe allergic reactions (anaphylactic and anaphylactoid reactions) associated with use of neuromuscular blocking agents, including atracurium besylate.

These reactions, in some cases, have been life-threatening and fatal. Because these reactions were reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency (see WARNINGS and PRECAUTIONS ).

Drug Interactions Drugs which may enhance the neuromuscular blocking action of atracurium include: enflurane; isoflurane; halothane; certain antibiotics, especially the aminoglycosides and polymyxins; lithium; magnesium salts; procainamide; and quinidine. If other muscle relaxants are used during the same procedure, the possibility of a synergistic or antagonist effect should be considered. The prior administration of succinylcholine does not enhance the duration, but quickens the onset and may increase the depth, of neuromuscular block induced by atracurium besylate.

Atracurium should not be administered until a patient has recovered from succinylcholine-induced neuromuscular block.

Pregnancy Teratogenic Effects: Atracurium besylate has been shown to be potentially teratogenic in rabbits when given in doses up to approximately one-half the human dose. There are no adequate and well-controlled studies in pregnant women. Atracurium should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Atracurium besylate was administered subcutaneously on days 6 through 18 of gestation to non-ventilated Dutch rabbits. Treatment groups were given either 0.15 mg/kg once daily or 0.10 mg/kg twice daily. There was an increased incidence of certain spontaneously occurring visceral and skeletal anomalies or variations in one or both treated groups when compared to non-treated controls.

Pediatric Use Safety and effectiveness in pediatric patients below the age of 1 month have not been established.

Atracurium besylate is contraindicated in patients known to have a hypersensitivity to it. Use of atracurium besylate from multiple dose vials containing benzyl alcohol as a preservative is contraindicated in patients with a known hypersensitivity to benzyl alcohol.

There has been limited experience with overdosage of atracurium besylate. The possibility of iatrogenic overdosage can be minimized by carefully monitoring muscle twitch response to peripheral nerve stimulation. Excessive doses of atracurium can be expected to produce enhanced pharmacological effects.

Overdosage may increase the risk of histamine release and cardiovascular effects, especially hypotension. If cardiovascular support is necessary, this should include proper positioning, fluid administration, and the use of vasopressor agents if necessary. The patient’s airway should be assured, with manual or mechanical ventilation maintained as necessary.

A longer duration of neuromuscular block may result from overdosage and a peripheral nerve stimulator should be used to monitor recovery. Recovery may be facilitated by administration of an anticholinesterase reversing agent such as neostigmine, edrophonium, or pyridostigmine, in conjunction with an anticholinergic agent such as atropine or glycopyrrolate. The appropriate package inserts should be consulted for prescribing information.

Cardiovascular changes were minimal. Nonetheless the possibility of cardiovascular changes must be considered in the case of overdose. An adult patient (17 years of age) unintentionally received an initial dose of 1.3 mg/kg of atracurium besylate.

The patient experienced moderate hemodynamic changes (13% increase in mean arterial pressure and 27% increase in heart rate) which persisted for 40 minutes and did not require treatment. Deaths occurred within 2 minutes and were caused by respiratory paralysis. The subcutaneous LD 50 determined in non-ventilated male Wistar rats was 282.8 mg/kg.

Tremors, ptosis, loss of reflexes and respiratory failure preceded death which occurred 45 to 120 minutes after injection.