BNF for Children 2011-2012

642 15.1.5 Neuromuscular blocking drugs BNFC 2011–201215 AnaesthesiaLicensed use not licensed for use in children under 1yearIndication and doseTo avoid excessive dosage in obese children, doseshould be calculated on the basis of ideal weight forheightEnhancement and maintenance of anaesthesiain ventilated patients. By intravenous administrationNeonate by intravenous infusion 0.4–1 micrograms/kg/minute;additional doses of 1 microgram/kgcan be given by intravenous injectionduring the intravenous infusionChild 1 month–12 years initially by intravenousinjection 0.1–1 micrograms/kg over at least 30seconds (omitted if not required) then by intravenousinfusion 0.05–1.3 micrograms/kg/minuteaccording to anaesthetic technique and adjustedaccording to response; additional doses can begiven by intravenous injection during the intravenousinfusionChild 12–18 years initially by intravenous injection0.1–1 micrograms/kg over at least 30 seconds(omitted if not required) then by intravenousinfusion 0.05–2 micrograms/kg/minute accordingto anaesthetic technique and adjusted according toresponse; additional doses can be given by intravenousinjection during the intravenous infusionAdministration for intravenous injection, reconstituteto a concentration of 1 mg/mL; for continuous intravenousinfusion, dilute further with Glucose 5% orSodium Chloride 0.9% to a concentration of 20–25 micrograms/mL for Child 1–12 years or 20–250 micrograms/mL (usually 50 micrograms/mL) forChild 12–18 yearsUltiva c (GSK) 2Injection, powder for reconstitution, remifentanil (ashydrochloride), net price 1-mg vial = £5.12; 2-mg vial= £10.23; 5-mg vial = £25.5815.1.5 Neuromuscular blockingdrugsImportantThe drugs in this section should be used by experiencedpersonnel only.Neuromuscular blocking drugs used in anaesthesia arealso known as muscle relaxants. By specific blockadeof the neuromuscular junction they enable light anaesthesiato be used with adequate relaxation of the musclesof the abdomen and diaphragm. They also relax thevocal cords and allow the passage of a tracheal tube.Their action differs from the muscle relaxants used inmusculoskeletal disorders (section 10.2.2) that act onthe spinal cord or brain.Children who have received a neuromuscular blockingdrug should always have their respiration assisted orcontrolled until the drug has been inactivated or antagonised(section 15.1.6). They should also receive sufficientconcomitant inhalational or intravenous anaestheticor sedative drugs to prevent awareness.Non-depolarising neuromuscularblocking drugsNon-depolarising neuromuscular blocking drugs (alsoknown as competitive muscle relaxants) compete withacetylcholine for receptor sites at the neuromuscularjunction and their action can be reversed with anticholinesterases,such as neostigmine (section 15.1.6).Non-depolarising neuromuscular blocking drugs can bedivided into the aminosteroid group, comprising pancuronium,rocuronium, and vecuronium, and the benzylisoquinoliniumgroup, which includes atracurium,cisatracurium, and mivacurium.Non-depolarising neuromuscular blocking drugs have aslower onset of action than suxamethonium. Thesedrugs can be classified by their duration of action asshort-acting (15–30 minutes), intermediate-acting (30–40 minutes), and long-acting (60–120 minutes),although duration of action is dose-dependent. Drugswith a shorter or intermediate duration of action, suchas atracurium and vecuronium, are more widely usedthan those with a longer duration of action, such aspancuronium.Non-depolarising neuromuscular blocking drugs haveno sedative or analgesic effects and are not consideredto trigger malignant hyperthermia.For children receiving intensive care and who requiretracheal intubation and mechanical ventilation, a nondepolarisingneuromuscular blocking drug is chosenaccording to its onset of effect, duration of action, andside-effects. Rocuronium, with a rapid onset of effect,may facilitate intubation. Atracurium or cisatracuriummay be suitable for long-term neuromuscular blockadesince their duration of action is not dependent onelimination by the liver or the kidneys.Cautions Allergic cross-reactivity between neuromuscularblocking drugs has been reported; caution isadvised in cases of hypersensitivity to these drugs. Theiractivity is prolonged in children with myasthenia gravisand in hypothermia, therefore lower doses are required.Non-depolarising neuromuscular blocking drugs shouldbe used with great care in those with other neuromusculardisorders and those with fluid and electrolytedisturbances, as response in these children is unpredictable.Resistance may develop in children with burnswho may require increased doses; low plasma cholinesteraseactivity in these children requires dose titrationfor mivacurium. The rate of administration of neuromuscularblocking drugs should be reduced in childrenwith cardiovascular disease. Interactions: Appendix 1(muscle relaxants).Pregnancy Non-depolarising neuromuscular blockingdrugs are highly ionised at physiological pH and aretherefore unlikely to cross the placenta in significantamounts.Breast-feeding Because they are ionised at physiologicalpH, non-depolarising neuromuscular blockingdrugs are unlikely to be present in milk in significantamounts. Breast-feeding may be resumed once themother has recovered from neuromuscular block.