Fat Emulsion for Complete Intravenous Nutrition

Targeted siRNA Delivery Using Lipid Nanoparticles

Efficient intracellular delivery of small-interfering ribonucleic acid (siRNA) to the target organ or tissues in the body is assumed as the main hurdle for a widespread use of siRNAs in the clinics. Solid lipid-based nanoparticles (SLNs) and derivatives can potentially fit this purpose by enabling to overcome the extracellular and intracellular physiological barriers affecting the delivery. For that, rational formulations and rational process designs are needed. This chapter addresses a comprehensive description and critical appraisal of the main production methods of this particular type of lipid nanoparticles and the leading strategies to prompt a targeted delivery of siRNA.

Protein Adsorption Patterns and Analysis on IV Nanoemulsions-The Key Factor Determining the Organ Distribution

Intravenous nanoemulsions have been on the market for parenteral nutrition since the 1950s; meanwhile, they have also been used successfully for IV drug delivery. To be well tolerable, the emulsions should avoid uptake by the MPS cells of the body; for drug delivery, they should be target-specific. The organ distribution is determined by the proteins adsorbing them after injection from the blood (protein adsorption pattern), typically analyzed by two-dimensional polyacrylamide gel electrophoresis, 2-D PAGE. The article reviews the 2-D PAGE method, the analytical problems to be faced and the knowledge available on how the composition of emulsions affects the protein adsorption patterns, e.g., the composition of the oil phase, stabilizer layer and drug incorporation into the interface or oil core. Data were re-evaluated and compared, and the implications for the in vivo distribution are discussed. Major results are that the interfacial composition of the stabilizer layer is the main determining factor and that this composition can be modulated by simple processes. Drug incorporation affects the pattern depending on the localization of the drug (oil core versus interface). The data situation regarding in vivo effects is very limited; mainly, it has to be referred to in the in vivo data of polymeric nanoparticles. As a conclusion, determination of the protein adsorption patterns can accelerate IV nanoemulsion formulation development regarding optimized organ distribution and related pharmacokinetics.

Does intravenous fat spare nitrogen in the injured rat?

The role of glucose versus fat as a source of energy in parenteral nutrition is controversial, particularly when administered after trauma, injury or in sepsis. In the present series of experiments, rats undergoing laparotomy and jugular vein cannulation were infused with hypertonic glucose or Intralipid with and without amino acids. The results demonstrate that the combination of amino acids and glucose has a better nitrogen-conserving ability than amino acids and fat, lasting at least 4 days after injury. However, when infused without amino acids, fat had the same nitrogen-conserving quality as glucose. The authors attribute the improved nitrogen-conserving quality of amino acids and glucose to the specific carbohydrate influence on amino acid metabolism, an action which is specific in both protein-free and protein-containing meals but has only very limited effect in the absence of simultaneously infused or fed amino acids. In the moderately to severely injured rat, a glucose calorie is significantly more effective in sparing nitrogen than a fat calorie.