Risk of Medication Errors
Accidental administration of neuromuscular blocking agents may be fatal. Store succinylcholine chloride injection with the prefilled syringe and cap intact, and in a manner that minimizes the possibility of selecting the wrong product [see Warnings and Precautions (5.3)].
For Short Surgical Procedures
The average dose required to produce neuromuscular blockade and to facilitate tracheal intubation is 0.6 mg/kg succinylcholine chloride given intravenously. The optimum intravenous dose of succinylcholine chloride injection will vary among patients and may be from 0.3 mg/kg to 1.1 mg/kg for adults. Following intravenous administration of doses in this range, neuromuscular blockade develops in about 1 minute; maximum blockade may persist for about 2 minutes, after which recovery takes place within 4 to 6 minutes. A 5 to 10 mg intravenous test dose of succinylcholine chloride may be used to determine the sensitivity of the patient and the individual recovery time [see Warnings and Precautions (5.9)].
For Long Surgical Procedures
Continuous Intravenous Infusion
The dosage of succinylcholine chloride injection administered by continuous intravenous infusion depends upon the duration of the surgical procedure and the need for muscle relaxation.
Diluted succinylcholine chloride Injection solutions containing from 1 mg/mL to 2 mg/mL succinylcholine have commonly been used for continuous intravenous infusion [see Dosage and Administration (2.5)]. The more dilute solution (1 mg/mL) is probably preferable from the standpoint of ease of control of the rate of administration of succinylcholine chloride injection and, hence, of relaxation. This diluted succinylcholine chloride injection solution containing 1 mg/mL may be administered intravenously at a rate of 0.5 mg (0.5 mL) per minute to 10 mg (10 mL) per minute to obtain the required amount of relaxation. The amount required per minute will depend upon the individual response as well as the degree of relaxation required. The average rate of continuous intravenous infusion for an adult ranges between 2.5 mg per minute and 4.3 mg per minute.
Monitor neuromuscular function with a peripheral nerve stimulator when using succinylcholine chloride injection by infusion in order to avoid overdose, detect development of Phase II block, follow its rate of recovery, and assess the effects of reversing agents [see Warnings and Precautions (5.8)].
Intermittent Intravenous Injection
Intermittent intravenous injections of succinylcholine chloride injection may also be used to provide muscle relaxation for long procedures. An intravenous injection of 0.3 mg/kg to 1.1 mg/kg may be given initially, followed, at appropriate intervals, by further intravenous injections of 0.04 mg/kg to 0.07 mg/kg to maintain the degree of relaxation required.
Risk Summary
Available data from published literature from case reports and case series over decades of use with succinylcholine during pregnancy have not identified a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes. Succinylcholine is used commonly during delivery by caesarean section to provide muscle relaxation. If succinylcholine is used during labor and delivery, there is a risk for prolonged apnea in some pregnant women (see Clinical Considerations). Animal reproduction studies have not been conducted with succinylcholine chloride.
The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively.
Clinical Considerations
Maternal Adverse Reactions
Plasma cholinesterase levels are decreased by approximately 24% during pregnancy and for several days postpartum which can prolong the effect of succinylcholine. Therefore, some pregnant patients may experience prolonged apnea.
Fetal/Neonatal Adverse Reactions
Apnea and flaccidity may occur in the newborn after repeated high doses to, or in the presence of atypical plasma cholinesterase, in the mother.
Labor or Delivery
Succinylcholine is commonly used to provide muscle relaxation during delivery by caesarean section. Succinylcholine is known to cross the placental barrier in an amount that is dependent on the concentration gradient between the maternal and fetal circulation.
Risk Summary
There are no data on the presence of succinylcholine or its metabolite in either human or animal milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for succinylcholine chloride injection and any potential adverse effects on the breastfed infant from succinylcholine chloride injection or from the underlying maternal condition.
Elimination
Succinylcholine levels were reported to be below the detection limit of 2 μg/mL after 2.5 minutes of an intravenous bolus dose of 1 or 2 mg/kg in 14 anesthetized patients.
Metabolism
Succinylcholine is rapidly hydrolyzed by plasma cholinesterase to succinylmonocholine (which possesses clinically insignificant depolarizing muscle relaxant properties) and then more slowly to succinic acid and choline.
Excretion
About 10% of the drug is excreted unchanged in the urine.
Specific Populations
Pediatric Patients
Due to the relatively large volume of distribution in the pediatric patient versus the adult patient, the effective dose of succinylcholine chloride injection in pediatric patients may be higher than that predicted by body weight dosing alone [see Dosage and Administration (2.3)].
Carcinogenesis
There have been no long-term studies performed in animals to evaluate carcinogenic potential of succinylcholine.
Mutagenesis
Adequate studies have not been completed to evaluate the genotoxic potential of succinylcholine.
Impairment of Fertility
There are no studies to evaluate the potential impact of succinylcholine on fertility.