Droplet-size distribution and stability of commercial injectable lipid emulsions containing fish oil

Lipid emulsions in clinical nutrition: Enteral and parenteral nutrition

Clinical nutrition emulsions are important products that can be life-saving for many patients suffering from gastrointestinal tract disorders, swallowing impairment, cancer, liver diseases, and many other clinical conditions. The transfer of lipids to the human body can be either intravenously (Parenteral Nutrition, PN) or through the gastrointestinal tract (Enteral Nutrition, EN). PN emulsions are considered pharmaceuticals and thus regulated accordingly. On the other hand, EN emulsions are classified as Food for Specific Medical Purposes (FSMP) and do not follow pharmaceutical regulations. Regarding product design, PN emulsions must follow theoretical emulsion formulation and production aspects, but special requirements regarding droplet size distribution must be followed to comply with national pharmacopeia monographs. Furthermore, a full clinical program on clinical evidence to prove safety and efficacy must be provided for marketing approval. On the contrary, EN emulsions require limited clinical evidence to substantiate health or clinical benefits. A short introduction to clinical nutrition with a focus on lipid emulsions is presented in this chapter. Furthermore, a general overview of the composition and main ingredients of clinical nutrition lipid emulsions is reviewed. Main clinical aspects are also mentioned here, highlighting the difficulties of clinically proving the efficacy of these products. The manufacturing and control of clinical nutrition emulsions are also reviewed, focusing on PN products and the main regulatory requirements related to the safety of these intravenous emulsions. Finally, stability and physicochemical properties are reviewed, and examples of commercially available products are used to illustrate these properties linked to the stability of these products. Lipids in clinical nutrition is a moving field and we do hope this chapter may remain a valuable source to understand newly emerging research on this topic.

Relation between Droplet Size Distributions and Physical Stability for Zein Microfluidized Emulsions

Zein, a subproduct of the food industry and a protein, possesses limited applications due to its high hydrophobic character. The objective of this research was to investigate the influence of homogenization pressure and cycles on the volumetric mean diameter (D_4,3), span values, and Turbiscan Stability Index (TSI) using the response surface methodology for microfluidized emulsions containing zein as a unique stabilizer. Results showed that homogenization pressure seems to be the most influential parameter to obtain enhanced physical stability and droplet size distributions, with the optimum being 20,000 psi. Interestingly, the optimum number of cycles for volumetric diameter, span value, and TSI is not the same. Although a decrease of D_4,3 with number of cycles is observed (optimum three cycles), this provokes an increase of span values (optimum one cycle) due to the recoalescence effect. Since physical stability is influenced by D_4,3 and span, the minimum for TSI is observed at the middle level of the cycles (2 cycles). This work highlights that not only volumetric diameter, but also span value must be taken into consideration in order to obtain stable zein emulsions. In addition, this study wants to extend the limited knowledge about zein-based emulsions processed with a Microfluidizer device.

Biological and Clinical Aspects of an Olive Oil-Based Lipid Emulsion-A Review

Intravenous lipid emulsions (ILEs) have been an integral component of parenteral nutrition for more than 50 years. Numerous formulations are available and are based on vegetable (soybean, olive, coconut) and animal (fish) oils. Therefore, each of these formulations has a unique fatty acid composition that offers both benefits and limitations. As clinical experience and our understanding of the effects of fatty acids on various physiological processes has grown, there is evidence to suggest that some ILEs may have benefits compared with others. Current evidence suggests that olive oil-based ILE may preserve immune, hepatobiliary, and endothelial cell function, and may reduce lipid peroxidation and plasma lipid levels. There is good evidence from a large randomized controlled study to support a benefit of olive oil-based ILE over soybean oil-based ILE on reducing infections in critically ill patients. At present there is limited evidence to demonstrate a benefit of olive oil-based ILE over other ILEs on glucose metabolism, and few data exist to demonstrate a benefit on clinical outcomes such as hospital or intensive care unit stay, duration of mechanical ventilation, or mortality. We review the current research and clinical evidence supporting the potential positive biological and clinical aspects of olive oil-based ILE and conclude that olive oil-based ILE is well tolerated and provides effective nutritional support to various PN-requiring patient populations. Olive oil-based ILE appears to support the innate immune system, is associated with fewer infections, induces less lipid peroxidation, and is not associated with increased hepatobiliary or lipid disturbances. These data would suggest that olive oil-based ILE is a valuable option in various PN-requiring patient populations.

Compatibility of intravenous ibuprofen with lipids and parenteral nutrition, for use as a continuous infusion

There is increasing interest to administer ibuprofen as a continuous infusion instead of a traditional bolus for treating Patent Ductus Arteriosus (PDA). However, its compatibility data with commonly used drugs in the neonatal period, including parenteral nutrition (PN) and lipids is unavailable. The aim is to determine the compatibility of intravenous ibuprofen lysine with various ANZNN parenteral nutrition consensus group standard neonatal PN formulations and lipids. The PN and lipid solutions used in a tertiary neonatal unit were obtained. These included a Starter, Standard Preterm and low carbohydrate PN, and IV SMOF lipid admixture (SMOFLipid 20% 15 mL; Vitalipid N infant 4 mL, Soluvit N 1 mL) plus vitamin mixtures. 10% glucose was used as a control. 1:1 mixtures of different concentrations (1.25 to 5mg/mL) of ibuprofen lysine and each of the PN/glucose/lipid formulations were made. Samples were taken at hourly intervals for a total of 4 hours and tested for both physical (visual assessment, pH and microscopy) and chemical compatibility (High Performance Liquid Chromatography analysis). Zeta potential and particle diameter were measured for SMOF lipid admixture and ibuprofen combination to assess emulsion stability. 24 hour stability of ibuprofen dilution in 5 mL BD Luer-lok polypropylene syringes at 25°C was also assessed. Most PN formed opaque solutions when mixed with ibuprofen 2.5 and 5mg/mL solutions. However, ibuprofen dilution of 1.25mg/mL produced clear, colourless solutions with no microscopic particles when mixed with all PN/glucose/lipid formulations tested. Ibuprofen was chemically stable with all PN and SMOF lipid admixture, for a period of 4 hours. The zeta potential and particle diameter were within acceptable limits. Ibuprofen lysine was stable over 24 hours in Luer-lok polypropylene syringes. Ibuprofen 1.25mg/mL is physically and chemically compatible with 10% glucose, starter PN, standard preterm and low carbohydrate PN, and SMOF lipid admixture plus vitamins for a period of four hours, which is the maximum time they could be in an admixture during a continuous infusion.

Intravenous Lipid Emulsions in Parenteral Nutrition

Fat is an important macronutrient in the human diet. For patients with intestinal failure who are unable to absorb nutrients via the enteral route, intravenous lipid emulsions play a critical role in providing an energy-dense source of calories and supplying the essential fatty acids that cannot be endogenously synthesized. Over the last 50 y, lipid emulsions have been an important component of parenteral nutrition (PN), and over the last 10-15 y many new lipid emulsions have been manufactured with the goal of improving safety and efficacy profiles and achieving physiologically optimal formulations. The purpose of this review is to provide a background on the components of lipid emulsions, their role in PN, and to discuss the lipid emulsions available for intravenous use. Finally, the role of parenteral fat emulsions in the pathogenesis and management of PN-associated liver disease in PN-dependent pediatric patients is reviewed.