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Cysteine Hydrochloride

Pronunciation: SIS-te-een HYE-droe-KLOR-ide
Class: Amino acid

Trade Names

Cysteine Hydrochloride
- Injection, solution, concentrate 50 mg/mL

L-Cysteine Hydrochloride
- Injection, solution, concentrate 50 mg/mL


Essential amino acid in infants.

Indications and Usage

As an additive to crystalline amino acid solution to meet the IV amino acid nutritional requirements of infants receiving TPN.


Hepatic coma; metabolic disorders involving impaired nitrogen utilization.

Dosage and Administration


Not intended for use in adults.


IV 500 mg (10 mL) of cysteine injection combined with 12.5 g of crystalline amino acid injection (eg, 250 mL of 5% injection). The admixture is then diluted with 250 mL of dextrose 50% or such lesser volume as indicated.

General Advice

  • Do not give undiluted. Add to crystalline amino acid injection.
  • Use within 1 h of mixing. Otherwise, refrigerate immediately and use within 24 h.
  • Add to TPN solution.
  • Use of large peripheral veins, in-line filters, and slowing the rate of infusion may reduce the incidence of local venous irritation.


Store between 59° and 86°F.

Drug Interactions


Tetracycline may reduce the nitrogen-sparing effects of infused amino acids.

Adverse Reactions




Erythema, phlebitis, thrombosis at the infusion site, warm sensation.


Fever, generalized flushing.



Monitor glucose, urea nitrogen, serum electrolytes, ammonia, cholesterol, acid-base balance, serum proteins, kidney and liver function tests, osmolarity, and hemogram. WBC and blood cultures are to be determined if indicated. Urinary osmolarity and glucose should be determined frequently. Carefully monitor nitrogen intake in patients with impaired renal function.


Not indicated for use in pregnant women.


Not indicated for use in breast-feeding women.


The effect of infusion of amino acids, without dextrose, upon carbohydrate metabolism of children is not known at this time.

Renal Function

May increase BUN. Discontinue if BUN levels exceed normal postprandial limits and continue to rise. A modest rise in BUN normally occurs as a result of increased protein intake.

Hepatic Function

May increase BUN, and cause serum amino acid imbalances, metabolic alkalosis, prerenal azotemia, hyperammonemia, stupor, and coma.

Special Risk Patients

Use with caution in patients with a history of renal disease, pulmonary disease, or with cardiac insufficiency to avoid excessive fluid accumulation. Use sodium-containing solutions with caution, if at all, in patients with CHF or severe renal insufficiency, and in clinical states in which there exists edema with sodium retention. Use potassium-containing solutions with caution, if at all, in patients with hyperkalemia or severe renal failure, and in clinical states in which potassium retention is present. Use acetate-containing solutions with caution in patients with metabolic or respiratory alkalosis and in those conditions in which there is an increased level or an impaired utilization of this ion (eg, severe hepatic insufficiency).


Use caution when administering hypertonic glucose to provide calories in diabetic or prediabetic patients.

Aluminum toxicity

Parenteral products may contain 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.

Exogenous calories

Provide exogenous calories concurrently with amino acids in patients receiving long-term total nutrition or if the patient has inadequate fat stores.


May result in mental retardation in infants. Monitor blood ammonia levels frequently.

Patient Information

  • Advise patient that medication will be prepared and administered by a health care provider in a hospital setting.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.