cysteine (Rx)

Brand and Other Names:Elcys, Nouress
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

injectable solution

  • 50mg/mL (single-dose 10-mL vial)

Total Parenteral Nutrition

Indicated for adults with severe liver disease who may have impaired enzymatic processes and require total parenteral nutrition (TPN)

May also be added to amino acid (AA) solutions to provide a more complete profile of AAs for protein synthesis

Stable patients

  • Recommended protein requirement: 0.8-1 g AA/kg/day
  • Recommended dose: 7 mg/g AA
  • Recommended volume: 0.14 mL/g AA

Critically ill patients

  • Recommended protein requirement: 1.5-2 g AA/kg/day
  • Recommended dose: 7 mg/g AA
  • Recommended volume: 0.14 mL/g AA

Dosage Modifications

Renal impairment

  • Clinically evaluate and closely monitor renal function (eg, serum electrolytes, fluid balance)

Hepatic impairment

  • Clinically evaluate and closely monitor liver function (eg, bilirubin, liver function parameters)

Dosing Considerations

Dosage of final parenteral nutrition solution containing cysteine must be based on concentration of all components in the solution and recommended nutritional requirements

Dosage of cysteine should be individualized based on patient’s clinical condition, body weight, and nutritional/fluid requirements

Prior to administration, correct severe fluid, electrolyte, and acid-base disorders

Dosage Forms & Strengths

injectable solution

  • 50mg/mL (single-dose 10-mL vial)

Total Parenteral Nutrition

Indicated to fulfill nutritional requirements of newborn infants requiring TPN and of pediatric patients with severe liver disease who may have impaired enzymatic processes and require TPN

May also be added to AA solutions to provide a more complete profile of AAs for protein synthesis

Preterm and term infants (<1 month)

  • Recommended protein requirement: 3-4 g AA/kg/day
  • Recommended dose: 22 mg/g AA
  • Recommended volume: 0.44 mL/g AA

1 month to <1 year

  • Recommended protein requirement: 2-3 g AA/kg/day
  • Recommended dose: 22 mg/g AA
  • Recommended volume: 0.44 mL/g AA

1 to <12 years

  • Recommended protein requirement: 1-2 g AA/kg/day
  • Recommended dose: 22 mg/g AA
  • Recommended volume: 0.44 mL/g AA

12 to 17 years

  • Recommended protein requirement: 0.8-1.5 g AA/kg/day
  • Recommended dose: 7 mg/g AA
  • Recommended volume: 0.14 mL/g AA

Dosage Modifications

Renal impairment

  • Clinically evaluate and closely monitor renal function (eg, serum electrolytes, fluid balance)

Hepatic impairment

  • Clinically evaluate and closely monitor liver function (eg, bilirubin, liver function parameters)
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Interactions

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                    Adverse Effects

                    Frequency Not Defined

                    Local infusion site reactions, including a warm sensation, erythema, phlebitis, and thrombosis, at the infusion site

                    Generalized flushing, fever, and nausea

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                    Warnings

                    Contraindications

                    Hypersensitivity to one or more AAs

                    Inborn errors of AA metabolism due to risk of severe metabolic or neurologic complications

                    Pulmonary edema or acidosis due to low cardiac output

                    Cautions

                    Pulmonary vascular precipitates causing pulmonary vascular emboli and pulmonary distress reported; in some fatal cases, pulmonary embolism occurred due to calcium precipitates; if signs of pulmonary distress occur, stop parenteral nutrition infusion, initiate a medical evaluation, and periodically inspect the solution and infusion set

                    For admixture use only and must be diluted; it is not direct IV infusion; solutions with an osmolarity (>900 mOsm/L) infuse through a central catheter; infusion of hypertonic nutrient injections into a peripheral vein may result in vein irritation, vein damage, and/or thrombosis

                    IV infusion of AAs may induce a rise in BUN, especially in patients with impaired hepatic or renal function; perform appropriate laboratory tests periodically and discontinue infusion if BUN levels exceed normal postprandial limits and continue to rise

                    Administration may result in metabolic acidosis in preterm infants; administration of AA solutions to a patient with hepatic impairment may result in serum AA imbalances, metabolic alkalosis, prerenal azotemia, hyperammonemia, stupor, and coma; frequent clinical evaluation and laboratory determinations are necessary for proper monitoring of acid-base balance during parenteral nutrition

                    Hepatobiliary disorders are known to develop in some patients without preexisting liver disease who receive parenteral nutrition (eg, cholecystitis, cholelithiasis, cholestasis, hepatic steatosis, fibrosis, cirrhosis, possibly leading to hepatic failure); etiology of these disorders is thought to be multifactorial and may differ between patients; monitor liver function parameters and ammonia levels

                    Hyperammonemia is of special significance in infants, as it can result in neurocognitive delays; closely monitor blood ammonia levels in infants; instances of asymptomatic hyperammonemia reported in patients without overt liver dysfunction

                    Because of immature renal function, preterm infants receiving prolonged parenteral nutrition treatment may be at higher risk of aluminum toxicity

                    Monitor fluid and electrolyte status, serum osmolarity, blood glucose, liver and kidney function, blood cell count, and coagulation parameters throughout treatment

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                    Pregnancy & Lactation

                    Pregnancy

                    Appropriate administration is not expected to cause major birth defects, miscarriage, or adverse maternal or fetal outcomes

                    Animal reproduction studies have not been conducted with cysteine

                    Lactation

                    Data available on the effects of cysteine on infants, either directly or through breastmilk, do not suggest a significant risk of adverse events from exposure

                    Although there are no data on the presence of cysteine in human or animal milk or the effects on milk production, appropriate administration is not expected to cause harm to a breastfed infant

                    Consider the developmental and health benefits of breastfeeding along with the mother’s clinical need for the drug, and any potential adverse effects on the breastfed infant from the drug or from the underlying maternal condition

                    Pregnancy Categories

                    A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

                    B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

                    C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

                    D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

                    X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

                    NA: Information not available.

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                    Pharmacology

                    Mechanism of Action

                    Endogenous cysteine is synthesized from methionine by the enzyme, cystathionase, via the trans-sulfuration pathway, and serves as a precursor substrate for both glutathione and taurine; provides cysteine to systemic circulation of patients who require parenteral nutrition and cannot synthesize adequate quantities of cysteine due to insufficient or deficient cystathionase activity

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                    Administration

                    IV Compatibilities

                    Dextrose 5%

                    IV Incompatibilities

                    Evaluate all additions to the parenteral nutrition container for compatibility and stability of the resulting preparation

                    IV Preparation

                    Must be diluted and used as an admixture in parenteral nutrition solutions

                    Remove vial from the carton and inspect for particulate matter

                    Transfer required amount of cysteine to an AA solution using strict aseptic techniques to avoid microbial contamination

                    AA solution containing cysteine can then be used to prepare admixtures in the parenteral nutrition container using strict aseptic techniques

                    Follow the proper mixing sequence to minimize pH-related problems

                    • Transfer dextrose injection to the parental nutrition-pooling container
                    • Transfer phosphate salt
                    • Transfer cysteine-containing AA solution
                    • Transfer electrolytes Transfer trace elements

                    Use gentle agitation during admixing to minimize localized concentration effects; shake containers gently after each addition

                    Inspect the final parenteral nutrition solution containing cysteine to ensure that precipitates have not formed during mixing or addition of additives

                    Discard if any precipitates are observed

                    IV Administration

                    Not for direct IV infusion

                    Prepare only in a suitable work area such as a laminar flow hood (or an equivalent clean-air compounding area)

                    Use aseptic technique to avoid inadvertent touch contamination during mixing of solutions and addition of other nutrients

                    For addition to AA solutions prior to further admixing with dextrose injection using a parenteral nutrition container

                    IV lipid emulsions can be infused concurrently into the same vein as AA and dextrose solutions by a Y-connector located near the infusion site; flow rates of each solution should be controlled separately by infusion pumps

                    For administration without lipid emulsion, use a 0.22-micron in-line filter

                    To prevent air embolism, use a nonvented infusion set or close the vent on a vented set; avoid multiple connections

                    If infused with lipid emulsion, do not use administration sets and lines that contain di-2-ethylhexyl phthalate (DEHP); administration sets that contain polyvinyl chloride (PVC) components have DEHP as a plasticizer

                    Visually inspect diluted parenteral nutrition solution for particulate matter before admixing, after admixing, and prior to administration

                    Solution should be clear and there should be no precipitates; a slight yellow color does not alter the quality and efficacy of this product

                    Storage

                    Unused vials

                    • Store at 20-25°C (68-77°F); avoid excessive heat; protect from freezing
                    • If accidentally frozen, discard vial

                    Diluted solutions

                    • Use for admixing should be limited to up to 4 hr at room temperature (25ºC/77ºF) after container closure has been penetrated
                    • Discard any remaining drug
                    • Use parenteral nutrition solution containing cysteine promptly after mixing
                    • Any storage of the admixture should be refrigerated and for no longer than 24 hr
                    • After removal from refrigeration, use promptly and complete infusion within 24 hr; discard any remaining admixture
                    • Protect from light
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                    Patient Handout

                    A Patient Handout is not currently available for this monograph.
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                    Formulary

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                    The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

                    Tier Description
                    1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
                    2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
                    3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
                    4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
                    5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
                    6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
                    NC NOT COVERED – Drugs that are not covered by the plan.
                    Code Definition
                    PA Prior Authorization
                    Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
                    QL Quantity Limits
                    Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
                    ST Step Therapy
                    Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
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                    Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.