4.1. Therapeutic indications

Atracurium Besilate solution for injection/infusion is indicated as an adjunct to general anaesthesia during surgery to relax skeletal muscles, and to facilitate endotracheal intubation and mechanical ventilation. It is also indicated to facilitate mechanical ventilation in intensive care unit (ICU) patients. Atracurium Besilate solution for injection/infusion is indicated in adults and in paediatric patients aged over 1 month to 18 years.

4.2. Posology and method of administration

Atracurium Besilate solution for injection/infusion should only be administered by, or under the supervision of, anaesthesiologists or practitioners familiar with the use and action of neuromuscular blocking agents and only when facilities are immediately available for endotracheal intubation and for providing adequate ventilation support, including the administration of oxygen under positive pressure and the elimination of carbon dioxide. The clinician must be prepared to assist or control ventilation, and anticholinesterase agents should be immediately available for reversal of neuromuscular blockade.

Posology

Atracurium Besilate solution for injection/infusion should only be administered by intravenous injection/infusion. Do not give Atracurium Besilate solution for injection/infusion intramuscularly since this may result in tissue irritation and there are no clinical data to support this route of administration.

In common with all neuromuscular blocking agents, monitoring of neuromuscular function is recommended during the use of Atracurium Besilate solution for injection/infusion in order to individualise dosage requirements.

Use as an adjunct to general anaesthesia

To avoid distress to the patient, Atracurium Besilate solution for injection/infusion should not be administered before unconsciousness has been induced.

Initial bolus doses for intubation

An initial Atracurium Besilate solution for injection/infusion dose of 0.3 to 0.6 mg/kg (depending on the duration of full block required), given as an intravenous bolus injection, is recommended. This will provide adequate relaxation for about 15 to 35 minutes.

Endotracheal intubation can usually be accomplished within 90 to 120 seconds of the intravenous injection of 0.5 to 0.6 mg/kg. Maximum neuromuscular blockade is generally achieved approximately 3 to 5 minutes after administration. The recovery index (25% to 75%) is 10 to 15 minutes. Spontaneous recovery from the end of full block occurs in about 35 minutes as measured by the restoration of the tetanic response to 95% of normal neuromuscular function.

Maintenance doses

Intermittent IV injection

During prolonged surgical procedures neuromuscular blockade may be maintained with Atracurium Besilate solution for injection/infusion maintenance doses of 0.1 to 0.2 mg/kg. Successive supplementary dosing does not give rise to accumulation of neuromuscular blocking effect.

Use as an infusion

After the initial Atracurium Besilate solution for injection/infusion bolus dose, neuromuscular blockade may be maintained during prolonged surgical procedures by administering Atracurium Besilate solution for injection/infusion as a continuous intravenous infusion at a rate of 0.3 to 0.6 mg/kg/hour. The infusion should not be commenced until early spontaneous recovery from the initial atracurium bolus dose is evident. After infusion, the recovery index (25% to 75%) is 10 to 15 minutes, which is similar to that observed after intermittent injection.

Atracurium Besilate solution for injection/infusion can be administered by infusion during cardiopulmonary bypass surgery at the recommended infusion rates. Induced hypothermia to a body temperature of 25 ºC to 26 ºC reduces the rate of inactivation of atracurium, and therefore full neuromuscular block may be maintained with approximately half the original infusion rate at these temperatures.

Facilitation of mechanical ventilation in intensive care unit (ICU) patients

After an optional initial bolus dose of 0.3 to 0.6 mg/kg, neuromuscular block may be maintained by administering a continuous infusion of Atracurium Besilate solution for injection/infusion at rates of between 11 and 13 microgram/kg/min (0.65 to 0.78 mg/kg/hr). There may be wide inter-patient variability in dosage requirements, and these may increase or decrease with time. Infusion rates as low as 4.5 microgram/kg/min (0.27 mg/kg/hr) or as high as 29.5 microgram/kg/min (1.77 mg/kg/hr) are required in some patients.

The rate of spontaneous recovery from neuromuscular block after infusion of Atracurium Besilate solution for injection/infusion in ICU patients is independent of the duration of administration.

Spontaneous recovery to a train-of-four ratio > 0.75 (the ratio of the height of the fourth to the first twitch in a train-of-four) can be expected to occur in approximately 60 minutes. A range of 32 to 108 minutes has been observed in clinical trials.

Reversal of neuromuscular blockade

The neuromuscular blockade induced by atracurium can be reversed with an anticholinesterase agent such as neostigmine or pyridostigmine, usually in conjunction with an anticholinergic agent such as atropine or glycopyrronium to prevent the adverse muscarinic effects of the anticholinesterase. Under balanced anaesthesia, reversal can usually be attempted approximately 20 to 35 minutes after the initial atracurium dose, or approximately 10 to 30 minutes after the last atracurium maintenance dose, when recovery of muscle twitch has started. Complete reversal of neuromuscular blockade is usually achieved within 8 to 10 minutes after administration of the reversing agents.

Rare instances of breathing difficulties, possibly related to incomplete reversal, have been reported following attempted pharmacological antagonism of atracurium induced neuromuscular blockade. As with other agents in this class, the tendency for residual neuromuscular block is increased if reversal is attempted at deep levels of blockade or if inadequate doses of reversal agents are employed.

Dosage considerations

Use in the elderly

The standard dose of atracurium may be used in elderly patients, however, it is recommended that the initial dose be at the lower end of the range, and it should be administered slowly.

Use in patients with reduced renal and/or hepatic function

Standard dosages may be used at all levels of renal or hepatic function, including endstage failure.

Use in patients with cardiovascular disease

In patients with significant cardiovascular disease the initial dose of atracurium should be administered over a period of at least 60 seconds and the dose should be divided (see section 4.4).

Paediatric population

Use in paediatric patients aged over 1 month

The dosage in paediatric patients over the age of 1 month is similar to that in adults on a body weight basis, however, large individual variability in the neuromuscular response in paediatric patients indicates that neuromuscular monitoring is essential.

Use in neonates

The use of Atracurium solution for injection/infusion is not recommended in neonates since there are insufficient data available (see section 5.1).

Method of administration

For intravenous administration as a bolus injection or as a continuous infusion.

Atracurium Besilate solution for injection/infusion should not be mixed in the same syringe, or administered simultaneously through the same needle, with alkaline solutions (e.g., barbiturate solutions) (see section 4.4).

When a small vein is selected as the injection site, Atracurium solution for injection/infusion should be flushed through the vein with physiological saline after injection. When other anaesthetic drugs are administered through the same indwelling needle or cannula as Atracurium solution for injection/infusion, it is important that each drug is flushed through with an adequate volume of physiological saline.

See section 6.6 for a list of compatible infusion solutions.

4.3. Contraindications

• Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.

• Hypersensitivity to cisatracurium (see section 4.4).

4.4. Special warnings and precautions for use

Atracurium has no known effect on consciousness, pain threshold, or cerebration. In surgery, it should be used only with adequate general anaesthesia.

Anaphylactic reactions

Anaphylactic reactions to neuromuscular blocking agents in general have been reported (sometimes severe, such as shock, cardiac arrest). Although these phenomena only occur rarely with atracurium, precautions should always be taken to prevent the possible occurrence of these reactions (see also section 4.8).

Special precautions should be taken in patients with known anaphylactic reactions to neuromuscular blocking agents, as cross-reactivity may be possible with this product.

During administration of Atracurium Besilate solution for injection/infusion, special attention should be paid to patients with a history of hypersensitivity to other neuromuscular blocking agents, as high levels of crossed allergic reactions (greater than 50%) between neuromuscular blocking agents have been reported (see section 4.3).

In common with other neuromuscular blocking agents, the potential for histamine release exists in susceptible patients during administration of Atracurium Besilate solution for injection/infusion. Caution should be exercised in patients with a history suggestive of an increased sensitivity to the effects of histamine. Bronchospasms may occur, particularly in patients with a history of allergy or asthma. Caution is also recommended in atopic and asthmatic patients.

Do not give Atracurium Besilate solution for injection/infusion by intramuscular administration.

Atracurium Besilate solution for injection/infusion has an acid pH and therefore should not be mixed with alkaline solutions (e.g., barbiturate solutions) in the same syringe or administered simultaneously during intravenous infusion through the same needle. Depending on the resultant pH of such mixtures, Atracurium Besilate solution for injection/infusion may be inactivated, and a free acid may be precipitated.

Atracurium Besilate solution for injection/infusion may have profound effects in patients with myasthenia gravis, Eaton-Lambert syndrome, or other neuromuscular diseases in which potentiation of non-depolarising agents has been noted. A reduced dosage of Atracurium Besilate solution for injection/infusion and the use of a peripheral nerve stimulator for assessing neuromuscular blockade is especially important in these patients. Similar precautions should be taken in patients with severe electrolyte disorders.

Atracurium Besilate solution for injection/infusion does not have significant vagal or ganglion blocking properties in the recommended dosage range. Consequently, Atracurium Besilate solution for injection/infusion will not counteract the bradycardia produced by many anaesthetic agents or by vagal stimulation during surgery. Therefore, bradycardia during anaesthesia may be more common with Atracurium Besilate solution for injection/infusion than with other muscle relaxants.

As with other non-depolarising neuromuscular blocking agents, resistance to Atracurium Besilate solution for injection/infusion may develop in patients suffering from burns. Such patients may require increased doses of Atracurium Besilate solution for injection/infusion depending on the time elapsed since the burn injury and the extent of the burn.

Atracurium Besilate solution for injection/infusion should be administered over a period of at least 60 seconds to patients who may be unusually sensitive to falls in arterial blood pressure, for example those who are hypovolaemic.

Atracurium Besilate solution for injection/infusion is hypotonic and must not be applied into the infusion line of a blood transfusion.

Monitoring of serial creatine phosphokinase (CPK) values should be considered in asthmatic patients receiving high dose corticosteroids and neuromuscular blocking agents in intensive care units.

Intensive care unit (ICU) patients

The administration of laudanosine, the atracurium and cisatracurium metabolite, at high doses to laboratory animals has been accompanied by transient hypotension and in some species, cerebral excitatory effects. In the most sensitive animal species, these effects occurred for plasma laudanosine concentrations identical to those observed in ICU patients after prolonged infusion of atracurium.

There have been rare reports of seizures in ICU patients who had received Atracurium Besilate solution for injection/infusion concurrently with several other agents. These patients usually had one or more medical conditions predisposing to seizures (e.g., cranial trauma, cerebral oedema, viral encephalitis, hypoxic encephalopathy, uraemia). In clinical trials, there appeared to be no correlation between plasma laudanosine concentration and the occurrence of seizures.

After prolonged administration of Atracurium Besilate solution for injection/infusion in severely ill patients under intensive care, some incidences of muscle weakness and/or myopathy occurred. Most patients were concomitantly treated with corticosteroids. A causal relationship with Atracurium Besilate solution for injection/infusion therapy has not been established.

4.5. Interaction with other medicinal products and other forms of interaction

As with other non-depolarising neuromuscular blocking agents, the magnitude and/or duration of the effects of Atracurium Besilate solution for injection/infusion may be increased as a result of an interaction with the following agents.

Inhalation anaesthetics: atracurium is potentiated by isoflurane, desflurane, sevoflurane and enflurane anaesthesia, and only marginally potentiated by halothane anaesthesia.

Antibiotics: including the aminoglycosides, polymyxins, spectinomycin, tetracyclines, lincosamides (e.g., lincomycin, clindamycin), vancomycin and telithromycin.

Anticonvulsants (acute administration only): phenytoin, carbamazepine.

Local anaesthetics: lidocaine.

Antiarrhythmic drugs: lidocaine, procainamide, quinidine.

Beta-blockers: propranolol, oxprenolol.

Antirheumatic drugs: chloroquine, d-penicillamine.

Calcium channel blockers: diltiazem, nicardipine, nifedipine, verapamil.

Diuretics: furosemide, thiazides, acetazolamide and possibly mannitol.

Ganglion blocking agents: trimetaphan, hexamethonium.

Others: dantrolene, parenteral magnesium sulphate, chlorpromazine, steroids, ketamine, lithium salts and quinine.

Rarely, some of the above drugs may aggravate or unmask latent myasthenia gravis or actually induce a myasthenic syndrome. In these situations a consequent increased sensitivity to Atracurium Besilate solution for injection/infusion would be expected.

The administration of combinations of non-depolarising neuromuscular blocking agents in conjunction with Atracurium Besilate solution for injection/infusion may produce a degree of neuromuscular blockade in excess of that which might be expected were an equipotent total dose of Atracurium Besilate solution for injection/infusion administered. Any synergistic effect may vary between different drug combinations.

Administration of anticholinesterases, usually used in the treatment of Alzheimer's disease, such as donepezil, may decrease the duration and intensity of the neuromuscular block induced by Atracurium Besilate solution for injection/infusion.

A depolarising muscle relaxant such as suxamethonium chloride should not be administered to prolong the neuromuscular blocking effects of non-depolarising blocking agents such as Atracurium Besilate solution for injection/infusion, as this may result in a prolonged and complex block which can be difficult to reverse with anticholinesterase drugs.

The prior use of suxamethonium reduces the onset (to maximum blockade) by approximately 2 to 3 minutes and may increase the depth of neuromuscular blockade induced by Atracurium Besilate solution for injection/infusion. Therefore, the initial Atracurium Besilate solution for injection/infusion dose should be reduced, and the reduced dose should not be administered until the patient has recovered from the neuromuscular blocking effects of suxamethonium.

The use of intravenous corticosteroids with neuromuscular blocking agents has been reported to antagonise neuromuscular blockades. In addition, prolonged co-administration of these agents may increase the risk and/or severity of myopathy resulting in prolonged flaccid paralysis following discontinuation of the neuromuscular blocking agent. The myopathy is usually reversible with recovery in several months.

The onset of neuromuscular blockade is likely to be lengthened and the duration of blockade shortened in patients receiving chronic anticonvulsant therapy (e.g., carbamazepine, phenytoin). However, if the anticonvulsants are given acutely, the neuromuscular blocking effects may be increased.

In principle, maintaining neuromuscular monitoring until complete reversal of neuromuscular blockade should permit detection of most interactions. Nevertheless, recurrence of neuromuscular blockade may occur, for example, upon treatment with post-surgical antibiotics.

Aminoglycosides, colistin and lincosamides

Potentiation of muscular blockade may occur when the antibiotic is administered parenterally and/or peritoneally before, during or after the neuromuscular blocking agent. Monitor the level of neuromuscular blockade at the end of anaesthesia.

4.6. Fertility, pregnancy and lactation

Pregnancy

Atracurium crosses the placenta but there have been no demonstrated adverse effects in the foetus or newborn infant. Animal studies have indicated that atracurium has no adverse effects on foetal development. As with all neuromuscular blocking agents, the use of Atracurium Besilate solution for injection/infusion in the first three months of pregnancy should be avoided and it should not be used during the second and third trimesters unless clearly necessary.

Atracurium Besilate solution for injection/infusion is suitable for maintenance of muscle relaxation during caesarean section as it does not cross the placenta in clinically significant amounts following recommended doses. In an open-label study, atracurium besilate (0.3 mg/kg) was administered to 26 pregnant women during delivery by caesarean section. No harmful effects were attributable to atracurium in any of the newborn infants, although small amounts of atracurium were shown to cross the placental barrier. The possibility of respiratory depression in the newborn infant should always be considered following caesarean section during which a neuromuscular blocking agent has been administered.

Anaesthesia during the third trimester of pregnancy exposes the mother to Mendelson syndrome (acid pneumopathy due to gastric acid aspiration). If a muscle relaxant is used at induction of anaesthesia, one should be chosen with a short onset and duration of action and low placental transfer and used in the lowest dose required to induce adequate neuromuscular relaxation. In patients receiving magnesium sulphate, the reversal of neuromuscular blockade may be unsatisfactory and the Atracurium Besilate solution for injection/infusion dose should be lowered as indicated.

Breast-feeding

Atracurium has a relatively high molecular weight and is highly ionized at physiologic pH, both factors that markedly reduce transfer into milk. In addition, even though milk is slightly more acidic than plasma, any atracurium transferred into milk would be rapidly degraded. Nevertheless, in view of the potential respiratory depressant effect on the neonate, especially if premature, breast-feeding should be discontinued for 24 hours after administration of Atracurium Besilate solution for injection/infusion.

Fertility

No fertility data are available.

4.7. Effects on ability to drive and use machines

Atracurium Besilate solution for injection/infusion in combination with other anaesthetic agents can have major influence on the ability to drive and use machines. It is not recommended to use potentially dangerous machinery or drive a car within 24 hours after full recovery from the neuromuscular blocking action of atracurium.

4.8. Undesirable effects

The adverse effects are reported in decreasing order of frequency within each system order class (SOC).

As with most neuromuscular blocking agents, the potential exists for undesirable effects suggestive of histamine release in susceptible patients. In clinical trials (875 patients) reports of skin flushing ranged from 1% at doses up to 0.3 mg/kg, to 29% at doses of 0.6 mg/kg or greater. The incidence of transient hypotension ranged from 1% to 14% respectively for the corresponding dosages.

Table for frequency of adverse reactions for Atracurium Besilate solution for injection/infusion

System organ class

Common

(≥ 1/100 to < 1/10)

Uncommon

(≥ 1/1,000 to < 1/100)

Rare

(≥ 1/10,000 to < 1/1,000

Very rare

(< 1/10,000)

Not known (cannot be estimated from the available data)

Immune system disorders

Anaphylactic shock,.

anaphylactic reaction, anaphylactoid reaction

Cardiac disorders

Tachycardia, bradycardia

Cardiac arrest, cardiac failure*

Vascular disorders

Hypertension, hypotension, vasodilatation (flushing)

Respiratory, thoracic and mediastinal disorders

Wheezing

Bronchospasm

Dyspnoea, laryngospasm

Hypoxemia

Bronchial secretions

Skin and subcutaneous tissue disorders

Localised skin reactions, rash, itching

Generalised erythema, hives

Angioneurotic oedema, urticaria

General disorders and administration site conditions

Reaction at injection site

Injury, poisoning and procedural complications

Neuromuscular block prolonged

* In the context of severe allergic reactions.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.

4.9. Overdose

Prolonged muscle paralysis and its consequences are the main signs of overdose.

There is limited experience with atracurium overdosage following parenteral administration. The possibility of iatrogenic overdosage can be minimised by carefully monitoring muscle twitch response to peripheral nerve stimulation. Excessive doses of Atracurium Besilate solution for injection/infusion are likely to produce symptoms consistent with extensions of the usual pharmacological effects. Overdosage may increase the risk of histamine release and adverse cardiovascular effects, especially hypotension. If cardiovascular support is necessary, this should include proper positioning, fluid administration, and the use of vasopressor agents if necessary. It is essential to maintain a patent airway with assisted positive pressure ventilation until spontaneous respiration is adequate. Full sedation will be required since consciousness is not impaired. The duration of neuromuscular blockade may be prolonged, and a peripheral nerve stimulator should be used to monitor recovery. Recovery may be hastened by the administration of an anticholinesterase agent such as neostigmine or pyridostigmine in conjunction with an anticholinergic agent such as atropine, once evidence of spontaneous recovery is present.