cysteine (Rx)

Frequency Not Defined

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

Generalized flushing, fever, and nausea

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

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.

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

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