296
Stability of Three-in-One
TPN
Solutions To the Editor: I read with great interest and enthusiasm the article titled &dquo;Three-in-One Parenteral Nutrition: A Safe and Economical Method of Nutritional Support for Infants&dquo;
(JPEN 14:290-294, 1990). Only limited information is available
on the use of this economical method of nutritional support for infants. It is most encouraging to see researchers attempting to adapt such knowledge and experience with adults, to the pediatric scene. Dr C. Rollins et al carefully consider and discuss the factors affecting calcium and phosphate compatibility in parenteral nutrition solutions, particularly the shift in pH as a result of lipid addition. In addition to the question of the calcium and phosphate compatibility, the stability of the lipid emulsion should be considered. Factors such as pH, dextrose, amino acids, trace elements and electrolytes, particularly multivalent cations, greatly effect lipid stability. It has been postulated that multivalent cation may ’bridge’ between neighboring negatively charged phosphate groups on neighboring oil droplets. Critical aggregation numbers can be calculated to predict lipid stability and they have been 2 derived from well-known theories of colloidal science.2 I wish to invite the authors to comment on the stability of their three-in-one solutions with respect to lipid rather than calcium and phosphate compatibility. more
lipid emulsions.’-’ Despite this, our experience at the University of Arizona Health Sciences Center suggests that three-in-one PN formulations are quite stable. The incidence of lipid destabilization, as judged by visible creaming and/or cracking of three-in-one PN solutions, has been less than 0.5% for formulations prepared for children and under 0.1 % for formulations pre-
pared for adults over the past 3 years. This represents lipid destabilization of solutions prepared for three pediatric patients and three adult patients. One solution prepared for an adult patient receiving PN at home destabilized beyond its 7-day expiration date. The cracking of another solution involving a home pediatric patient occurred shortly after mixing and may be partially explained by the use of Troph Amine (Kendall McGaw, Irvine, CA) for PN preparation. Troph Amine is not among those amino acid formulations evaluated and considered compatible with Intralipid (KabiVitrum, Alameda, CA).~ The remaining four incidents of lipid destabilization were not explainable on the basis of any known destabilizing factors or deviations from the standard protocol for three-in-one PN preparation at the University of Arizona Health Sciences Center. The critical aggregation number (CAN) is mentioned by Mr Lilley in relation to predicting lipid stability. The CAN refers to the cationic concentration at, and above, which lipid particles aggregate because of neutralization of their anionic surface groups. These anionic groups normally maintain lipid emulsion stability because of the repulsive forces generated from the -30 to -40 mV surface charges or zeta potential. 6,1 Calculation of the CAN is accomplished using the following formula:
BRIAN LILLEY
Deputy Director of Pharmacy Royal Children’s Hospital Melbourne, Victoria Australia REFERENCES 1. Brown R, Querica R, Sigman R: Total nutrient admixture: A review. JPEN 10:650-658, 1986 2. Allwood MC: Compatibility and stability of TPN mixtures in big bags. J Clin Hosp Pharm 9:181-198, 1984
where A mmol monovalent cation per liter of PN, B mmol mmol divalent cation per liter of PN, and C trivalent cation per liter of PN.6 For Intralipid alone, aggregation of lipid particles occurs when the CAN is between 130 and 200.~ Considering that the CAN is well above 200 for the majority of PN solutions prepared at the Arizona Health Sciences Center and given the low incidence of lipid destabilization mentioned previously, it does not seem that the CAN is clinically useful in predicting three-in-one PN solution =
=
=
destabilization.
Response
to Mr
Lilley’s Letter
To the Editor: Thank you for the
opportunity to respond to Mr Lilley’s inquiry concerning the stability of lipid emulsions in parenteral nutrition solutions. The stability of lipid emulsions is certainly a major consideration with respect to three-in-one parenteral nutrition (PN) solutions. As indicated by Mr Lilley in his letter, numerous factors are reported to destabilize
There are two possible explanations for this. First, Gimble and Silk’ suggest that charge reversal may stabilize lipid systems when the CAN is high and that lipid destabilization occurs only when the CAN is approximately 130 to 200. The second possible explanation is that the CAN may be inappropriately applied to lipid emulsions, since it was developed for less complex systems with electrical potentials greater than +50 V.7 Lipid emulsions are complex low-voltage systems with electrical potentials (zeta potentials) of -30 to -40 m V.6,7 In conclusion, our experience at the Arizona Health Sciences Center indicates that lipid destabilization with three-in-one PN solutions occurs infrequently. When destabilization does occur, a complex interaction between factors seems to be responsible since an individual destabilizing factor is not usually identified.
Downloaded from pen.sagepub.com at MICHIGAN STATE UNIV LIBRARIES on June 13, 2015
Stability of Three-in-One
TPN
Solutions To the Editor: I read with great interest and enthusiasm the article titled &dquo;Three-in-One Parenteral Nutrition: A Safe and Economical Method of Nutritional Support for Infants&dquo;
(JPEN 14:290-294, 1990). Only limited information is available
on the use of this economical method of nutritional support for infants. It is most encouraging to see researchers attempting to adapt such knowledge and experience with adults, to the pediatric scene. Dr C. Rollins et al carefully consider and discuss the factors affecting calcium and phosphate compatibility in parenteral nutrition solutions, particularly the shift in pH as a result of lipid addition. In addition to the question of the calcium and phosphate compatibility, the stability of the lipid emulsion should be considered. Factors such as pH, dextrose, amino acids, trace elements and electrolytes, particularly multivalent cations, greatly effect lipid stability. It has been postulated that multivalent cation may ’bridge’ between neighboring negatively charged phosphate groups on neighboring oil droplets. Critical aggregation numbers can be calculated to predict lipid stability and they have been 2 derived from well-known theories of colloidal science.2 I wish to invite the authors to comment on the stability of their three-in-one solutions with respect to lipid rather than calcium and phosphate compatibility. more
lipid emulsions.’-’ Despite this, our experience at the University of Arizona Health Sciences Center suggests that three-in-one PN formulations are quite stable. The incidence of lipid destabilization, as judged by visible creaming and/or cracking of three-in-one PN solutions, has been less than 0.5% for formulations prepared for children and under 0.1 % for formulations pre-
pared for adults over the past 3 years. This represents lipid destabilization of solutions prepared for three pediatric patients and three adult patients. One solution prepared for an adult patient receiving PN at home destabilized beyond its 7-day expiration date. The cracking of another solution involving a home pediatric patient occurred shortly after mixing and may be partially explained by the use of Troph Amine (Kendall McGaw, Irvine, CA) for PN preparation. Troph Amine is not among those amino acid formulations evaluated and considered compatible with Intralipid (KabiVitrum, Alameda, CA).~ The remaining four incidents of lipid destabilization were not explainable on the basis of any known destabilizing factors or deviations from the standard protocol for three-in-one PN preparation at the University of Arizona Health Sciences Center. The critical aggregation number (CAN) is mentioned by Mr Lilley in relation to predicting lipid stability. The CAN refers to the cationic concentration at, and above, which lipid particles aggregate because of neutralization of their anionic surface groups. These anionic groups normally maintain lipid emulsion stability because of the repulsive forces generated from the -30 to -40 mV surface charges or zeta potential. 6,1 Calculation of the CAN is accomplished using the following formula:
BRIAN LILLEY
Deputy Director of Pharmacy Royal Children’s Hospital Melbourne, Victoria Australia REFERENCES 1. Brown R, Querica R, Sigman R: Total nutrient admixture: A review. JPEN 10:650-658, 1986 2. Allwood MC: Compatibility and stability of TPN mixtures in big bags. J Clin Hosp Pharm 9:181-198, 1984
where A mmol monovalent cation per liter of PN, B mmol mmol divalent cation per liter of PN, and C trivalent cation per liter of PN.6 For Intralipid alone, aggregation of lipid particles occurs when the CAN is between 130 and 200.~ Considering that the CAN is well above 200 for the majority of PN solutions prepared at the Arizona Health Sciences Center and given the low incidence of lipid destabilization mentioned previously, it does not seem that the CAN is clinically useful in predicting three-in-one PN solution =
=
=
destabilization.
Response
to Mr
Lilley’s Letter
To the Editor: Thank you for the
opportunity to respond to Mr Lilley’s inquiry concerning the stability of lipid emulsions in parenteral nutrition solutions. The stability of lipid emulsions is certainly a major consideration with respect to three-in-one parenteral nutrition (PN) solutions. As indicated by Mr Lilley in his letter, numerous factors are reported to destabilize
There are two possible explanations for this. First, Gimble and Silk’ suggest that charge reversal may stabilize lipid systems when the CAN is high and that lipid destabilization occurs only when the CAN is approximately 130 to 200. The second possible explanation is that the CAN may be inappropriately applied to lipid emulsions, since it was developed for less complex systems with electrical potentials greater than +50 V.7 Lipid emulsions are complex low-voltage systems with electrical potentials (zeta potentials) of -30 to -40 m V.6,7 In conclusion, our experience at the Arizona Health Sciences Center indicates that lipid destabilization with three-in-one PN solutions occurs infrequently. When destabilization does occur, a complex interaction between factors seems to be responsible since an individual destabilizing factor is not usually identified.
Downloaded from pen.sagepub.com at MICHIGAN STATE UNIV LIBRARIES on June 13, 2015
