From the FDA Drug Label
The average dose required to produce neuromuscular blockade and to facilitate tracheal intubation is 0.6 mg/kg Succinylcholine Chloride Injection given intravenously. The optimum dose will vary among individuals and may be from 0.3 to 1.1 mg/kg for adults. Intermittent intravenous injections of succinylcholine may also be used to provide muscle relaxation for long procedures. An intravenous injection of 0.3 to 1.1 mg/kg may be given initially, followed, at appropriate intervals, by further injections of 0.04 to 0.07 mg/kg to maintain the degree of relaxation required.
The recommended dose for a second dose of succinylcholine is 0.04 to 0.07 mg/kg given at appropriate intervals to maintain the degree of relaxation required, as the initial dose is 0.3 to 1.1 mg/kg.
- The dosage of succinylcholine should be individualized and determined by the clinician after careful assessment of the patient.
- Neuromuscular function should be carefully monitored with a peripheral nerve stimulator when using succinylcholine by infusion to avoid overdose and detect development of Phase II block 1.
From the Research
The recommended dose for a second administration of succinylcholine is typically 50-100% of the initial dose (0.5-1.0 mg/kg), based on clinical need and duration of action required. When administering a repeat dose, it should only be given after recovery from the first dose has begun and only if absolutely necessary for continued muscle relaxation. Timing is crucial - the second dose should generally be administered no sooner than 5-10 minutes after the initial dose. Repeated doses of succinylcholine can lead to prolonged neuromuscular blockade, cardiovascular effects including bradycardia, and increased risk of hyperkalemia, as seen in studies such as 2 which highlights the risk of hyperkalemia in critically ill patients. Phase II block (a non-depolarizing type of blockade) may develop with repeated or high doses, resulting in prolonged recovery time. Monitoring with a peripheral nerve stimulator is essential when administering repeat doses, as suggested by the need for careful management of neuromuscular function 3. Clinicians should be prepared to provide continued ventilatory support and have alternative non-depolarizing neuromuscular blocking agents available if longer paralysis is needed, as repeated succinylcholine administration is generally not recommended for extended procedures.
Some key considerations when administering a second dose of succinylcholine include:
- The potential for increased risk of bradycardia, particularly in pediatric patients, although studies such as 4 suggest that the routine use of atropine before succinylcholine in children may not be necessary.
- The importance of monitoring for signs of hyperkalemia, especially in critically ill patients, as highlighted by 2.
- The need for careful timing and dosing to avoid prolonged neuromuscular blockade and Phase II block, as discussed in 3.
- The availability of alternative non-depolarizing neuromuscular blocking agents for extended procedures, to minimize the risks associated with repeated succinylcholine administration.
Overall, the decision to administer a second dose of succinylcholine should be made with caution, taking into account the potential risks and benefits, and with careful consideration of the individual patient's needs and clinical context, as informed by the most recent and highest quality evidence, such as 3.