title: Quality assessment of total parenteral nutrition admixtures by the use of fractional factorial design.
abstract: OBJECTIVE
  Parenteral nutrition as a specific as pect of providing nutritients still remains a permanent topic of both theoretical and experimental research. Total parenteral nutrition (TPN) admixtures have complex con tents making difficult to maintain their stability. The most critical parameter is the diameter of a lipid droplet, i.e. droplet size distribution. It is recommended that droplet size should not be more than 5 microm and that the presence of greater droplets should not exceede the value of 0.05%. Lipid droplets size is affected particularly by electrolyte addition, especially polyvalent cations. There is a danger of the added electrolytes interaction with lipid droplets which leads to their aggregation and negative effects upon the admixtures stability. The aim of this study was to as sess the effect of added electrolyte and lipid phase quan tity on the admixture stability.
  
  
  METHODS
  Electrolytes were added to the studied admixture of a defined basic formulation contents in accordance with recommenda tions from the literature. Droplets size measurements were performed using the method of laser diffraction with a laser particles analyzer. Effects of independent variables were calculated and evaluated using commercial software. Na(+), K(+), Ca(2+) and Mg(2+) concentrations, as well as the quantity of fat phase were chosen as studied fac tors, i.e. independed variables. The system response, or dependent variable was the median of droplets size. Each of the factors was varied at two levels, higher (+1) and lower (-1), according to the 2(5-2) fractional factorial design.
  
  
  RESULTS
  The study suggested the presence of relative uni formity of the results of all the measurements regardless of the quantity of added electrolytes and lipid phase. It was shown that undoubtedly there is the influence of 2 valent cations (calcium and magnesium) upon lipid drop lets size, which is in a direct correlation with theoretical assumption.
  
  
  CONCLUSIONS
  Within a 72-hour testing period there was no significant increase in droplet size, i.e. the studied admixtures remained stable considering droplet size median as the criterion of stability.
authors.affiliation: Pharmacy Department, Military Medical Academy, Belgrade, Serbia. ducim@eunet.rs
authors.forename: Dusica
authors.initials: D
authors.lastname: Mirković
authors.forename: Svetlana
authors.initials: S
authors.lastname: Ibrić
authors.forename: Mirjana
authors.initials: M
authors.lastname: Antunović
mesh_terms: D004355:Drug Stability; D005217:Fat Emulsions, Intravenous; D006801:Humans; D008055:Lipids / Q000737:chemistry; D010289:Parenteral Nutrition, Total / Q000592:standards; D010316:Particle Size; D011786:Quality Control
chemical_list: D005217:Fat Emulsions, Intravenous; D008055:Lipids