L-CYSTEINE HYDROCHLORIDE � cysteine hydrochloride injection, solution
American Regent, Inc.
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Rx Only
FOR INTRAVENOUS ADMINISTRATION AFTER DILUTION
DESCRIPTION
L-Cysteine Hydrochloride Injection, USP is a sterile, nonpyrogenic solution. Each mL contains: LCysteine Hydrochloride (Monohydrate) 50 mg, Water for Injection q.s. pH (range between 1.0 and 2.5) may be adjusted with Concentrated Hydrochloric Acid and/or Sodium Hydroxide. L-Cysteine is a sulfur containing amino acid. In premixed solutions of crystalline amino acids, cysteine is relatively unstable over time, eventually converting to insoluble cystine. To avoid such precipitation, L-Cysteine Hydrochloride Injection, USP is intended to be used as an additive with Crystalline Amino Acid Injections immediately prior to administration to the patient.
The structural formula of L-Cysteine Hydrochloride Monohydrate USP is:
1923c5a9-figure-01
(click image for full-size original)
CLINICAL PHARMACOLOGY
L-Cysteine is synthesized from methionine via the trans-sulfuration pathway in the adult, but newborn infants lack the enzyme necessary to effect this conversion. Therefore, L-Cysteine is generally considered to be an essential amino acid in infants.
INDICATIONS AND USAGE
L-Cysteine Hydrochloride Injection, USP is indicated for use only after dilution as an additive to Crystalline Amino Acid Injections to meet the intravenous amino acid nutritional requirements of infants receiving total parenteral nutrition.
CONTRAINDICATIONS
This preparation should not be used in patients with hepatic coma or metabolic disorders involving impaired nitrogen utilization.
WARNINGS
Peripheral intravenous infusion of amino acids may induce a rise in blood urea nitrogen (BUN) especially in patients with impaired hepatic or renal function. Appropriate laboratory tests should be performed periodically and infusion discontinued if BUN levels exceed normal postprandial limits and continue to rise. It should be noted that a modest rise in BUN normally occurs as a result of increased protein intake.
Administration of amino acid solutions to a patient with hepatic insufficiency may result in serum amino acid imbalances, metabolic alkalosis, prerenal azotemia, hyperammonemia, stupor and coma.
Administration of amino acid solutions in the presence of impaired renal function may augment an increasing BUN, as does any protein dietary component.
Solutions containing sodium ion should be used with great care, if at all, in patients with congestive heart failure, severe renal insufficiency, and in clinical states in which there exists edema with sodium retention.
Solutions which contain potassium ion should be used with great care, if at all, in patients with hyperkalemia, severe renal failure and in conditions in which potassium retention is present.
Solutions containing acetate ion should be used with great care in patients with metabolic or respiratory alkalosis.
Acetate should be administered with great care in those conditions in which there is an increased level or an impaired utilization of this ion such as severe hepatic insufficiency.
Hyperammonemia is of special significance in infants, as it can result in mental retardation. Therefore, it is essential that blood ammonia levels be measured frequently in infants.
Instances of asymptomatic hyperammonemia have been reported in patients without overt liver dysfunction. The mechanisms of this reaction are not clearly defined but may involve genetic defects and immature or subclinically impaired liver function.
This product contains aluminum that may be toxic. Aluminum may reach toxic levels with prolonged parenteral administration if kidney function is impaired. Premature neonates are particularly at risk because their kidneys are immature, and they require large amounts of calcium and phosphate solutions, which contain aluminum.
Research indicates that patients with impaired kidney function, including premature neonates, who receive parenteral levels of aluminum at greater than 4 to 5 mcg/kg/day accumulate aluminum at levels associated with central nervous system and bone toxicity. Tissue loading may occur at even lower rates of administration.
