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.

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 Adverse Reactions * Includes the recommended initial dosage range for most patients. Adverse Reaction Initial Atracurium Dose (mg/kg) 0.00 to 0.30 (n = 485) 0.31 to 0.50 * (n = 366) > 0.60 (n = 24) Total (n = 875) Skin Flush 1% 8.7% 29.2% 5% Erythema 0.6% 0.5% 0% 0.6% Itching 0.4% 0% 0% 0.2% Wheezing/Bronchial Secretions 0.2% 0.3% 0% 0.2% Hives 0.2% 0% 0% 0.1% 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 * Includes the recommended initial dosage range for most patients. Vital Sign Change Initial Atracurium Dose (mg/kg) 0.00 to 0.30 (n = 365) 0.31 to 0.50 * (n = 144) > 0.60 (n = 21) Total (n = 530) Mean Arterial Pressure Increase 1.9% 2.8% 0% 2.1% Decrease 1.1% 2.1% 14.3% 1.9% Heart Rate Increase 1.6% 2.8% 4.8% 2.1% Decrease 0.8% 0% 0% 0.6% 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. Lethal respiratory distress occurred in two 0.15 mg/kg animals and in one 0.10 mg/kg animal, with transient respiratory distress or other evidence of neuromuscular block occurring in 10 of 19 and in 4 of 20 of the 0.15 mg/kg and 0.10 mg/kg animals, respectively.

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. The percentage of male fetuses was lower (41% vs. 51%) and the post-implantation losses were increased (15% vs. 8%) in the group given 0.15 mg/kg once daily when compared to the controls; the mean numbers of implants (6.5 vs. 4.4) and normal live fetuses (5.4 vs. 3.8) were greater in this group when compared to the control group.

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.

Three pediatric patients (3 weeks, 4 and 5 months of age) unintentionally received doses of 0.8 mg/kg to 1 mg/kg of atracurium besylate. The time to 25% recovery (50 to 55 minutes) following these doses, which were 5 to 6 times the ED 95 dose, was moderately longer than the corresponding time observed following doses 2 to 2.5 times the atracurium ED 95 dose in infants (22 to 36 minutes). 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 time from injection to 25% recovery (83 minutes) was approximately twice that observed following maximum recommended doses in adults (35 to 45 minutes). 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. The intravenous LD 50 s determined in non-ventilated male and female albino mice and male Wistar rats were 1.9, 2.01 and 1.31 mg/kg, respectively.

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.