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Parenteral Nutrition Cysteine Product Shortage Considerations 

September, 2011


There is a growing and critical shortage of L-cysteine needed for parenteral nutrition (PN) in the neonatal population.  We have heard from many consumer groups, healthcare systems, and clinicians regarding their short supplies or inability to obtain this product.  For the most up-to-date supply information, please see these websites:

American Society of Health-System Pharmacists (ASHP), Drug Shortages Resource Center: 

A.S.P.E.N. News section (on homepage):  


While there is no replacement for L-cysteine, dose conservation measures can be taken.  Under general feeding and growth circumstances there is no need to supplement PN with L-cysteine while providing a minimum of 3 g/kg per day protein.  This will provide adequate methionine when using commonly-prescribed amino acid solutions.  The American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) has developed conservation recommendations in order to cope with the shortages.  If the shortage persists, patients will go untreated or have nutrient imbalances.  We consider the lack of L-cysteine injections to be a serious health issue for neonatal patients requiring PN in the U.S.


During the L-cysteine shortage period, consider one or more of the following measures:


  1. If there is some product available, restrict L-cysteine supplementation in PN to neonates <1 kg or those neonates >1 kg who are at high risk for cysteine deficiency such as neonates who are post-surgical or those with sepsis.
  2. Normal needs for PN L-cysteine are estimated to be 30-40 mg/g of protein provided.  However, studies have documented that as little as 20 mg/g of protein provided is adequate.
  3. Assess each patient as to the indication for PN and provide nutrition via the oral or enteral route when possible.
  4. Purchase only as much L-cysteine injections supply as needed.  In the interest of fair allocation to all patients nationally, please do not stockpile.
  5. Reconsider / discourage using L-cysteine as an agent to re-establish intravascular access catheter patency.
  6. Compound PN in a single, central location (either in a centralized pharmacy or as outsourced preparation) in order to decrease inventory waste.  Consider a supply outreach to other facilities in your geographic location.
  7. If using an automated compounding device (ACD) to prepare PN formulations add the L-cysteine to the PN as a separate additive rather than adding it to the amino acid solution (so that it is pumped as a single product).  This will conserve supplies and reserve its use for the intended population.  Consult the ACD manufacturer for proper placement of L-cysteine on the ACD configuration.  If you compound manually, add the L-cysteine to the PN immediately before or after adding the amino acids solution and prior to adding the calcium.
  8. When removing or reducing the dose of PN L-cysteine re-evaluate the calcium-phosphorus solubility charts or software to insure that a precipitate will not develop due to the increase in the pH of the PN formulation.  Consider using calcium-phosphorus solubility data that do not include the presence of L-cysteine in the PN formulation.
  9. Facilities and practitioners must continue to observe and be compliant with the product labeling (e.g., package insert), USP General Chapter <797> Pharmaceutical Compounding-Sterile Preparations, and state Boards of Pharmacy rules and regulations.
  10. Report severe drug product shortage information to the FDA Drug Shortage Program (DSP). See:  
  11. Report any patient problems related to shortages to ISMP Medication Errors Reporting Program (MERP).  To access that reporting mechanism, click here.



Suggested Readings:


  1. Riedijk MA, van Beek RHT, Voortman G, de Bie HMA, Dassel ACM, van Goudoever JB.  Cysteine: a conditionally essential amino acid in low-birth-weight preterm infants? Am J Clin Nutr. 2007;86:1120-1125.
  2. Riedijk MA, Voortman G, van Beek RHT, Baartsman MGA, Wafelman LS, van Goudoever JB.  Cyst(e)ine requirements in enterally fed very low birth weight infants. Pediatrics. 2008;121 (3):e561-567.
  3. Courtney-Martin G, Moore AM, Ball RO, Pencharz PB. The addition of cysteine to the total sulphur amino acid requirement as methionine does not increase erythrocytes glutathione synthesis in the parenterally fed human neonate. Pediatr Res. 2010;67:320-324.
  4. Shew SB, Keshen TH, Jahoo F, Jaksic T. Assessment of cysteine synthesis in very low–birth weight neonates using a [13C6]glucose tracer. J Pediatr Surg. 2005;40:52-56.
  5. Trissel LA.  Trissel’s Calcium and Phosphate Compatibility in Parenteral Nutrition, 2001.  TriPharma Communications, Houston, TX.


Important Note: These recommendations do not constitute medical or professional advice, and should not be taken as such.  To the extent the information published herein may be used to assist in the care of patients, this is the result of the sole professional judgment of the attending health professional whose judgment is the primary component of quality medical care.  The information presented herein is not a substitute for the exercise of such judgment by the health professional.

Developed by an ad hoc L-cysteine workgroup: Steve Plogsted, PharmD, BCNSP, CNSC (leader); Kathleen M. Gura, PharmD, BCNSP, FASHP; Richard A. Helms, PharmD; Daniel Robinson, MD;  and Christina Valentine, MD, MS, RD; the A.S.P.E.N. CPC Shortage Subcommittee: Beverly Holcombe, PharmD, BCNSP, FASHP (Chair); Deborah A Andris, MSN, APNP; Gary Brooks, PharmD, BCPS, BCNSP; Deborah R Houston, RPh, CIC, BCNSP; and Steve Plogsted, PharmD, BCNSP, CNSC.  Approved by the Clinical Practice Committee, and the A.S.P.E.N. Board of Directors.

Questions regarding these recommendations should be directed to Peggi Guenter, PhD, RN, CNSN, A.S.P.E.N. Director of Clinical Practice, Advocacy and Research Affairs at: 


Printable pdf of Considerations