NIMBEX

What it is

Nimbex is cisatracurium besilate injection. Nimbex injection is supplied in two strengths, either 2 mg or 5 mg of cisatracurium besilate per mL. Cisatracurium besilate, a stereoisomer of atracurium, is an intermediate duration, non-depolarising benzylisoquinolinium skeletal muscle relaxant. Cisatracurium besilate binds to cholinergic receptors on the motor end-plate to antagonise the action of acetylcholine, resulting in a competitive block of neuromuscular transmission.

Approved indications

— Relax skeletal muscles, and to facilitate tracheal intubation and mechanical ventilation during surgical and other procedures and in intensive care. — As an adjunct to general anaesthesia, or sedation in the intensive care unit.

Dosing overview

The recommended intubation dose of Nimbex injection for adults is 0.15 mg/kg bodyweight. A dose of 0.03 mg/kg bodyweight provides approximately 20 minutes of additional clinically effective neuromuscular block during opioid or propofol anaesthesia. For paediatric patients ages 1 month to 12 years, the recommended intubation dose of Nimbex injection is 0.15 mg/kg bodyweight administered rapidly over 5 to 10 seconds. For maintenance in paediatric patients, a dose of 0.02 mg/kg bodyweight provides approximately 9 minutes of additional clinically effective neuromuscular block during halothane anaesthesia. For maintenance of neuromuscular block by infusion, an initial infusion rate of 3 µg/kg/min (0.18 mg/kg/hr) is recommended to restore 89 to 99% T1 suppression following evidence of spontaneous recovery. After an initial period of stabilisation of neuromuscular block, a rate of 1 to 2 µg/kg/min (0.06 to 0.12 mg/kg/hr) should be adequate to maintain block in this range in most patients.

Key safety warnings

Cisatracurium besilate paralyses the respiratory muscles as well as other skeletal muscles but has no effect on consciousness or pain threshold. Nimbex injection should only be administered by, or under the supervision of, anaesthetists or other clinicians who are familiar with the use and action of neuromuscular blocking agents. Facilities for tracheal intubation and maintenance of pulmonary ventilation and adequate arterial oxygenation should be available. Laudanosine, a major biologically active metabolite of atracurium and cisatracurium without neuromuscular blocking activity, produces transient hypotension and, in higher doses, cerebral excitatory effects (generalised muscle twitching and seizures) when administered to several species of animals. Consistent with the decreased infusion rate requirements of cisatracurium, plasma laudanosine concentrations are approximately one third those following atracurium infusion. Patients with myasthenia gravis and other forms of neuromuscular disease have shown greatly increased sensitivity to non-depolarising blocking agents. An initial dose of not more than 0.02 mg/kg bodyweight cisatracurium besilate is recommended in these patients. Very rarely, severe anaphylactic reactions have been reported in patients receiving Nimbex in conjunction with one or more anaesthetic agents.

Contraindications

Nimbex injection is contraindicated in patients known to be hypersensitive to cisatracurium besilate, atracurium or benzenesulfonic acid.

Regulatory history

Nimbex cisatracurium besilate injection was first listed on the ARTG on 13 September 1996. The date of first approval was 13 September 1996.