Succinylcholine

Succinylcholine chloride injection is indicated in adults and pediatric patients: as an adjunct to general anesthesia to facilitate tracheal intubation to provide skeletal muscle relaxation during surgery or mechanical ventilation. Succinylcholine chloride is a depolarizing neuromuscular blocker indicated in adults and pediatric patients: as an adjunct to general anesthesia ( 1 ) to facilitate tracheal intubation (1 ) to provide skeletal muscle relaxation during surgery or mechanical ventilation. (1 )

Succinylcholine chloride injection, USP is supplied as a clear, colorless solution as follows: 200 mg/10 mL (20 mg/mL) in multiple-dose vials contains: 20 mg of succinylcholine anhydrous (equivalent to 22.65 mg of Succinylcholine chloride, USP). Injection: 200 mg/10 mL (20 mg/mL) in multiple-dose vials ( 3 )

Succinylcholine chloride injection is contraindicated: in patients with skeletal muscle myopathies [see Warnings and Precautions ( 5.1 )] in patients with known hypersensitivity to succinylcholine. Severe anaphylactic reactions to succinylcholine have been reported [see Warnings and Precautions ( 5.2) ] after the acute phase of injury following major burns, multiple trauma, extensive denervation of skeletal muscle, or upper motor neuron injury, which may result in severe hyperkalemia and cardiac arrest [see Warnings and Precautions ( 5.4 )] in patients with known or suspected genetic susceptibility to malignant hyperthermia [see Warnings and Precautions ( 5.5 ), Clinical Pharmacology ( 12.5 )] Skeletal muscle myopathies (4) Known hypersensitivity to succinylcholine (4 ) After the acute phase of injury following major burns, multiple trauma, extensive denervation of skeletal muscle, or upper motor neuron injury (4) Known or suspected genetic susceptibility to malignant hyperthermia ( 4)

Anaphylaxis: Severe anaphylactic reactions to neuromuscular blocking agents, including succinylcholine, have been reported. Some cases have been life-threatening and fatal. Take necessary precautions, such as the immediate availability of appropriate emergency treatment. ( 5.2 ) Risk of Death due to Medication Errors: Unintended administration of succinylcholine chloride injection may result in paralysis, respiratory arrest and death. Confirm proper selection of intended product and avoid confusion with other injectable solutions that are present in critical care and other clinical settings. ( 5.3) Hyperkalemia: Succinylcholine chloride injection may induce serious cardiac arrhythmias or cardiac arrest due to hyperkalemia. ( 5.4 ) Malignant Hyperthermia: Malignant hyperthermia may occur, especially in individuals with known or suspected susceptibility based on genetic factors or family history. Discontinue triggering agents, administer intravenous dantrolene sodium, and apply supportive therapies. ( 5.5 ) Bradycardia: Intravenous bolus administration may result in profound bradycardia or, rarely, asystole. The incidence is higher following a second dose of succinylcholine. Pretreatment with anticholinergic agents (e.g., atropine) may reduce the occurrence of bradyarrhythmias. ( 5.6 )

5.1 Ventricular Dysrhythmias, Cardiac Arrest, and Death From Hyperkalemic Rhabdomyolysis in Pediatric Patients There have been reports of ventricular dysrhythmias, cardiac arrest, and death secondary to acute rhabdomyolysis with hyperkalemia in apparently healthy pediatric patients who received succinylcholine. Many of these pediatric patients were subsequently found to have a skeletal muscle myopathy such as Duchenne muscular dystrophy whose clinical signs were not obvious. The syndrome often presented as sudden cardiac arrest within minutes after the administration of succinylcholine. These pediatric patients were usually, but not exclusively, males, and most frequently 8 years of age or younger. There have also been reports in adolescents. There may be no signs or symptoms to alert the practitioner to which patients are at risk. A careful history and physical may identify developmental delays suggestive of a myopathy. A preoperative creatine kinase could identify some but not all patients at risk. When a healthy-appearing pediatric patient develops cardiac arrest within minutes after administration of succinylcholine chloride injection, not felt to be due to inadequate ventilation, oxygenation or anesthetic overdose, immediate treatment for hyperkalemia should be instituted. Due to the abrupt onset of this syndrome, routine resuscitative measures are likely to be unsuccessful. Careful monitoring of the electrocardiogram may alert the practitioner to peaked T‑waves (an early sign). Administration of intravenous calcium, bicarbonate, and glucose with insulin, with hyperventilation have resulted in successful resuscitation in some of the reported cases. Extraordinary and prolonged resuscitative efforts have been effective in some cases. In addition, in the presence of signs of malignant hyperthermia, appropriate treatment should be initiated concurrently [see Warnings and Precautions ( 5.5 )]. Because it is difficult to identify which patients are at risk, reserve the use of succinylcholine chloride injection in pediatric patients for emergency intubation or instances where immediate securing of the airway is necessary, e.g., laryngospasm, difficult airway, full stomach, or for intramuscular use when a suitable vein is inaccessible.

5.2 Anaphylaxis Severe anaphylactic reactions to neuromuscular blocking agents, including succinylcholine, have been reported. These reactions have, in some cases, been life-threatening and fatal. Due to the potential severity of these reactions, the necessary precautions, such as the immediate availability of appropriate emergency treatment, should be taken. Allergic cross-reactivity between neuromuscular blocking agents, both depolarizing and non-depolarizing, has been reported in this class of drugs. Therefore, assess patients for previous anaphylactic reactions to other neuromuscular blocking agents before administering succinylcholine chloride injection.

5.3 Risk of Death due to Medication Errors Administration of succinylcholine chloride injection results in paralysis, which may lead to respiratory arrest and death; this progression may be more likely to occur in a patient for whom it is not intended. Confirm proper selection of intended product and avoid confusion with other injectable solutions that are present in critical care and other clinical settings. If another healthcare provider is administering the product, ensure that the intended dose is clearly labeled and communicated.

5.4 Hyperkalemia Succinylcholine chloride injection may induce serious cardiac arrhythmias or cardiac arrest due to hyperkalemia in patients with electrolyte abnormalities and those who may have digitalis toxicity. Succinylcholine chloride injection is contraindicated after the acute phase of injury following major burns, multiple trauma, extensive denervation of skeletal muscle, or upper motor neuron injury [see Contraindications ( 4 )] . The risk of hyperkalemia in these patients increases over time and usually peaks at 7 to 10 days after the injury. The risk is dependent on the extent and location of the injury. The precise time of onset and the duration of the risk period are undetermined. Patients with chronic abdominal infection, subarachnoid hemorrhage, or conditions causing degeneration of central and peripheral nervous systems are at an increased risk of developing severe hyperkalemia after succinylcholine chloride injection administration. Consider avoiding use of succinylcholine chloride injection in these patients or verify the patient’s baseline potassium levels are within the normal range prior to succinylcholine chloride injection administration.

5.5 Malignant Hyperthermia In susceptible individuals, succinylcholine may trigger malignant hyperthermia, a skeletal muscle hypermetabolic state leading to high oxygen demand. Fatal outcomes of malignant hyperthermia have been reported . The risk of developing malignant hyperthermia increases with the concomitant administration of succinylcholine and volatile anesthetic agents. Succinylcholine chloride injection can induce malignant hyperthermia in patients with known or suspected susceptibility based on genetic factors or family history, including those with certain inherited ryanodine receptor (RYR1) or dihydropyridine receptor (CACNA1S) variants [see Contraindications ( 4 ), Clinical Pharmacology ( 12.5 )]. Signs consistent with malignant hyperthermia may include hyperthermia, hypoxia, hypercapnia, muscle rigidity (e.g., jaw muscle spasm), tachycardia (e.g., particularly that unresponsive to deepening anesthesia or analgesic medication administration), tachypnea, cyanosis, arrhythmias, hypovolemia, and hemodynamic instability. Skin mottling, coagulopathies, and renal failure may occur later in the course of the hypermetabolic process. Successful treatment of malignant hyperthermia depends on early recognition of the clinical signs. If malignant hyperthermia is suspected, discontinue all triggering agents (i.e., volatile anesthetic agents and succinylcholine), administer intravenous dantrolene sodium, and initiate supportive therapies. Consult prescribing information for intravenous dantrolene sodium for additional information on patient management. Supportive therapies include administration of supplemental oxygen and respiratory support based on clinical need, maintenance of hemodynamic stability and adequate urinary output, management of fluid and electrolyte balance, correction of acid base derangements, and institution of measures to control rising temperature . […]

The following clinically significant adverse reactions are discussed in greater detail in other sections of the labeling: Ventricular Dysrhythmias, Cardiac Arrest, and Death from Hyperkalemic Rhabdomyolysis in Pediatric Patients [see Warnings and Precautions ( 5.1 )] Anaphylaxis [see Warnings and Precautions ( 5.2 )] Hyperkalemia [see Warnings and Precautions ( 5.4 )] Malignant Hyperthermia [see Warnings and Precautions ( 5.5 )] Bradycardia [see Warnings and Precautions ( 5.6 )] Increase in Intraocular Pressure [see Warnings and Precautions ( 5.7) ] Prolonged Neuromuscular Block due to Phase II Block and Tachyphylaxis [see Warnings and Precautions ( 5.8 )] The following adverse reactions associated with the use of succinylcholine were identified in clinical studies or postmarketing reports. Because some of these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure: Cardiovascular disorders : Cardiac arrest, arrhythmias, bradycardia, tachycardia, hypertension, hypotension Electrolyte disorders: Hyperkalemia Eye disorders: Increased intraocular pressure Gastrointestinal disorders: Excessive salivation Immune system disorders: Hypersensitivity reactions including anaphylaxis (in some cases life-threatening and fatal) Musculoskeletal disorders : Malignant hyperthermia, rhabdomyolysis with possible myoglobinuric acute renal failure, muscle fasciculation, jaw rigidity, postoperative muscle pain Respiratory disorders: Prolonged respiratory depression or apnea Skin disorders: Rash Adverse reactions reported with succinylcholine are cardiac arrest, malignant hyperthermia, arrhythmias, bradycardia, tachycardia, hypertension, hypotension, hyperkalemia, prolonged respiratory depression or apnea. (6) To report SUSPECTED ADVERSE REACTIONS, contact Dr. Reddy's Laboratories Inc., at 1-888-375-3784 or FDA at 1-800-FDA-1088 or www. fda.gov/medwatch.

Drugs that May Enhance the Neuromuscular Blocking Action of Succinylcholine: promazine, oxytocin, aprotinin, certain non-penicillin antibiotics, quinidine, β-adrenergic blockers, procainamide, lidocaine, trimethaphan, lithium carbonate, magnesium salts, quinine, chloroquine, isoflurane, desflurane, metoclopramide, terbutaline, and drugs that reduce plasma cholinesterase activity. ( 7.1)

7.1 Drugs that May Affect the Neuromuscular Blocking Action of Succinylcholine Chloride Injection Drugs that may enhance the neuromuscular blocking action of succinylcholine include: promazine, oxytocin, aprotinin, certain non-penicillin antibiotics, quinidine, β-adrenergic blockers, procainamide, lidocaine, trimethaphan, lithium carbonate, magnesium salts, quinine, chloroquine, isoflurane, desflurane, metoclopramide, and terbutaline. The neuromuscular blocking effect of succinylcholine may be enhanced by drugs that reduce plasma cholinesterase activity (e.g., chronically administered oral contraceptives, glucocorticoids, or certain monoamine oxidase inhibitors) or by drugs that irreversibly inhibit plasma cholinesterase [see Warnings and Precautions ( 5.9 )] . If other neuromuscular blocking agents are to be used during the same procedure, consider the possibility of a synergistic or antagonistic effect.

8.1 Pregnancy 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 to 4% and 15 to 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.

8.2 Lactation 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 and any potential adverse effects on the breastfed infant from succinylcholine chloride or from the underlying maternal condition.

8.4 Pediatric Use Safety and effectiveness of succinylcholine chloride have been established in pediatric patient age groups, neonate to adolescent. Because of a risk of ventricular dysrhythmias, cardiac arrest, and death from hyperkalemic rhabdomyolysis in pediatric patients, reserve the use of succinylcholine chloride injection in pediatric patients for emergency intubation or instances where immediate securing of the airway is necessary, e.g., laryngospasm, difficult airway, full stomach, or for intramuscular use when a suitable vein is inaccessible [see Warnings and Precautions ( 5.1 )]. Intravenous bolus administration of succinylcholine chloride injection in pediatric patients (including infants) may result in profound bradycardia or, rarely, asystole. The incidence and severity of bradycardia is higher in pediatric patients than adults [see Warnings and Precautions ( 5.6 )]. 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 )].

8.5 Geriatric Use Clinical studies of succinylcholine chloride did not include sufficient numbers of subjects aged 65 years and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

Succinylcholine is a depolarizing neuromuscular blocker. As does acetylcholine, it combines with the cholinergic receptors of the motor end plate to produce depolarization. This depolarization may be observed as fasciculations. Subsequent neuromuscular transmission is inhibited so long as adequate concentration of succinylcholine remains at the receptor site. Onset of flaccid paralysis is rapid (less than one minute after intravenous administration), and with single administration lasts approximately 4 to 6 minutes. The paralysis following administration of succinylcholine is progressive, with differing sensitivities of different muscles. This initially involves consecutively the levator muscles of the face, muscles of the glottis and finally the intercostals and the diaphragm and all other skeletal muscles.