Parenteral nutrition

Formulation of multifunctional oil-in-water nanosized emulsions for active and passive targeting of drugs to otherwise inaccessible internal organs of the human body

Oil-in-water (o/w) type nanosized emulsions (NE) have been widely investigated as vehicles/carrier for the formulation and delivery of drugs with a broad range of applications. A comprehensive summary is presented on how to formulate the multifunctional o/w NE for active and passive targeting of drugs to otherwise inaccessible internal organs of the human body. The NE is classified into three generations based on its development over the last couple of decades to make ultimately a better colloidal carrier for a target site within the internal and external organs/parts of the body, thus allowing site-specific drug delivery and/or enhanced drug absorption. The third generation NE has tremendous application for drug absorption enhancement and for 'ferrying' compounds across cell membranes in comparison to its first and second generation counterparts. Furthermore, the third generation NE provides an interesting opportunity for use as drug delivery vehicles for numerous therapeutics that can range in size from small molecules to macromolecules.

Efficacy and safety of an olive oil-based intravenous fat emulsion in adult patients on home parenteral nutrition

BACKGROUND

The most frequently used intravenous lipid emulsions are composed of 100% long chain triacylglycerols from soybean oil or of 50% long chain triacylglycerols-50% medium chain triacylglycerols. A newer emulsion, ClinOleic 20% containing 80% olive oil and 20% soybean oil, was suggested to reduce lipid peroxidation and immune function impairment.

AIM

To assess ClinOleic 20%'s efficacy, safety and effect upon systemic inflammatory parameters in adults on home parenteral nutrition.

METHODS

In stable home parenteral nutrition patients, the initial intravenous lipid emulsion was changed for ClinOleic 20%. Nutritional status, clinical and biological tolerance, and systemic inflammatory markers were analysed before and after 1 and 3 months of home parenteral nutrition, with ClinOleic 20% as intravenous lipid emulsion.

RESULTS

Clinical and biological nutritional markers and inflammatory parameters did not differ between day 0 and month +3. There was no essential fatty acids deficiency. No side-effects were reported. Three of five patients presenting with migraine during home parenteral nutrition infusion at day 0 felt consistently better at month +3.

CONCLUSIONS

ClinOleic 20% is safe and efficient in adult home parenteral nutrition. It maintains normal essential fatty acids status and did not influence inflammatory parameters. In contrast to studies in preterm infants or paediatric patients, no effect on vitamin E concentration or lipid peroxidation was observed.

Oil-in-water lipid emulsions: implications for parenteral and ocular delivering systems

Lipid emulsions (LEs) are heterogenous dispersions of two immiscible liquids (oil-in-water or water-in-oil) and they are subjected to various instability processes like aggregation, flocculation, coalescence and hence eventual phase separation according to the second law of thermodynamics. However, the physical stability of the LE can substantially be improved with help of suitable emulsifiers that are capable of forming a mono- or multi-layer coating film around the dispersed liquid droplets in such a way to reduce interfacial tension or to increase droplet-droplet repulsion. Depending on the concentrations of these three components (oil-water-emulsifier) and the efficiency of the emulsification equipments used to reduce droplet size, the final LE may be in the form of oil-in-water (o/w), water-in-oil (w/o), micron, submicron and double or multiple emulsions (o/w/o and w/o/w). The o/w type LEs (LE) are colloidal drug carriers, which have various therapeutic applications. As an intravenous delivery system it incorporates lipophilic water non-soluble drugs, stabilize drugs that tend to undergo hydrolysis and reduce side effects of various potent drugs. When the LE is used as an ocular delivery systems they increase local bioavailability, sustain the pharmacological effect of drugs and decrease systemic side effects of the drugs. Thus, the rationale of using LE as an integral part of effective treatment is clear. Following administration of LE through these routes, the biofate of LE associated bioactive molecules are somehow related to the vehicles disposition kinetics inside blood or eyeball. However, the LE is not devoid from undergoing various bio-process while exerting their efficacious actions. The purpose of this review is therefore to give an implication of LE for parenteral and ocular delivering systems.

In vitro adsorption of plasma proteins onto the surface (charges) modified-submicron emulsions for intravenous administration

Surface (charge) modified submicron emulsions (cationic and anionic) were prepared following the well established combined emulsification techniques and characterized for their droplet size distribution and surface charge. The effect of these emulsions on in vitro adsorption of plasma proteins was investigated by means of two dimensional polyacrylamide gel electrophoresis (2D PAGE). The presence of poloxamer 188 in tested emulsions effectively eliminated the adsorption of the larger proteins like immunoglobulins, fibrinogen, etc. However, depending on the type of surface charges, the smaller proteins such as apolipoproteins and albumin were almost completely adsorbed onto the submicron emulsions. Indeed, when compared to marketed lipofundin MCT 10%-and deoxycholic acid-based anionic emulsions, the adsorption of apolipoprotein, especially apoA-1, was approximately three times more on stearylamine-and oleylamine-based cationic emulsions and oleic acid-based anionic emulsions. In addition, the ratio between the apoA-1 and apoA-IV was found to be 1 for lipofundin MCT 10% whereas it was about 0.26 for deoxycholic acid-based anionic emulsion and above 5 for oleic acid-based anionic emulsions and cationic emulsions. This indicates that emulsions having similar surface/interfacial charge imparted by different anion-forming stabilizers (oleic or deoxycholic acids) exhibited markedly different protein adsorption patterns.

In vitro modulation of inflammatory cytokine production by three lipid emulsions with different fatty acid compositions

BACKGROUND AND AIMS

Studies have suggested that 100% long-chain triacylglycerols (LCTs) lipid emulsions exhibit immunosuppressive effects, sometimes suspected to favor infectious complications in patients receiving parenteral nutrition. Newer emulsions, in particular olive oil-based emulsions, seem to have lesser immunosuppressive effects. We studied the in vitro effect of 100% LCTs (Intralipide), 50% LCTs-50% medium chain triacylglycerols (Medialipide), and 80% olive oil-based lipid emulsions (ClinOleic) on inflammatory cytokines production by peripheral blood mononuclear cells (PBMCs).

METHODS

PBMCs separated by gradient centrifugation, or whole blood, were incubated with 0.001%, 0.01%, 0.1% and 1% of the three tested lipid emulsions during 24h in the presence or absence of activation by lipopolysaccharide and phytohemagglutinin. Then, supernatants were collected and cytokines measured (ELISA).

RESULTS

The three lipid emulsions reduced basal TNF-alpha and IL-1beta production in PBMCs and whole blood cultures. However, ClinOleic was significantly less powerful in TNF-alpha and IL-1beta inhibition by isolated PBMCs than Intralipide and Medialipide. Basal TNF-alpha production was equally inhibited by the three emulsions in whole blood, but IL-1beta production was not significantly modified by ClinOleic. Interleukin-6 and -8 were not affected. After cell activation, lipid emulsions exhibit no effect on cytokines production.

CONCLUSION

ClinOleic induces a significantly lower in vitro inhibition of TNF-alpha and IL-1beta production by PBMCs than 100% LCTs or 50% LCTs-50% MCTs emulsions, and therefore might be more immune neutral. These effects vary from one subject to another, and disappeared after cell activation. Therefore, caution must be taken before extrapolation in vivo. Provided information should be taken into account for future design of clinical trials studying the immune modulating properties of lipid emulsions.

Glutamine dipeptides in clinical nutrition

Glutamine is a conditional indispensable amino acid during stress. However, limited solubility and instability of glutamine prevent its addition to presently available nutritional preparations. To overcome these drawbacks, we propose the dipeptide concept by which stable and highly soluble synthetic glutamine containing dipeptides are used. The synthetic dipeptides fulfill all chemical/physical properties to be considered as parenteral substrates. Numerous experimental studies show rapid clearance of parenteral supplied glutamine containing dipeptides without accumulation in tissues; the loss via the urine being inconsequential. Differences related to the dipeptide structure are not observed. There is overwhelming evidence existent that a nutritional support with supplemental glutamine dipeptide positively influences nitrogen excretion, immune status, gut integrity, morbidity, rehabilitation and outcome. Consequently, omission of glutamine from conventional TPN and its subsequent administration should be considered as a replacement of a deficiency rather than a supplementation. It might thus be conceivable that the beneficial effects observed with glutamine nutrition are simply a correction of disadvantages produced by an inadequacy of conventional amino acid solutions. The availability of stable glutamine containing preparations will certainly facilitate an adequate amino acid nutrition in routine clinical setting during episodes of stress and malnutrition.

Fat emulsions based on structured lipids (1,3-specific triglycerides): an investigation of the in vitro interaction with plasma proteins

Structured lipids (1,3-specific triglycerides) are new chemical entities made by enzymatic transesterification of the fatty acids in the 1,3-positions of the triglyceride. The purpose of this study was to investigate the in vitro interaction of fat emulsions based on either structured lipids or vegetable oils with human plasma proteins employing two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). The structured lipids are triglycerides of the SLS and MLM types, where S is short-chain fatty acids (C4), M is medium-chain fatty acids (C8-10) and L is long-chain fatty acids (C16-18). The vegetable oil-based fat emulsions were the commercially available product, Intralipid, and a soybean oil (LLL) emulsion made de novo identically as the emulsions containing structured lipids. The SLS emulsion was found to adsorb a different protein pattern than the MLM and LLL emulsions. The protein pattern of the SLS emulsion was similar to the protein pattern of Intralipid. These findings might explain the in vivo difference in elimination found in another study, where the emulsion based on structured lipids with short-chain fatty acids in the 1,3-positions was removed more slowly from the general blood circulation compared to emulsions based on lipids with long-chain fatty acids in the 1,3-positions (LLL).

The potential use of parenteral dipeptides in clinical nutrition

The metabolic effects of intravenous peptides have undergone extensive investigation in recent years. Dipeptide solutions provide a mechanism for the provision of selected amino acids that may be conditionally indispensable under certain clinical conditions. In particular, amino acids such as cystine, glutamine, and tyrosine may be difficult to provide in their free form, but their availability can be increased substantially when they are supplied in the form of a dipeptide. Animal and human studies have demonstrated that parenteral dipeptides are cleared rapidly from the plasma compartment and favorably influence nitrogen equilibrium in healthy volunteers and catabolic patients. Certain dipeptides offer the potential for tailoring tissue-specific nutrition therapy. It seems likely that parenteral peptides will offer a major change in the delivery of intravenous nutrients.

Availability of glutamine supplied intravenously as alanylglutamine

In this review, new knowledge about the potential use of glutamine containing dipeptides as substrates in the frame of parenteral nutrition is presented. Using chemical and biotechnological methods, the stable and highly soluble peptide L-alanyl-L-glutamine (Ala-Gln) can be synthesized in high yields. Studies in experimental rats and dogs demonstrate the effective utilization of intravenously supplied Ala-Gln and the rapid provision of free glutamine for maintenance of the intracellular muscle-free glutamine pool in catabolic situations. Subsequent studies in healthy volunteers provide firm evidence that the infused Ala-Gln is rapidly eliminated from plasma (t1/2:3.8 minutes), associated by a prompt equimolar increase in the concentrations of free alanine and glutamine. Bolus injection and continuous infusion of the peptide was not accompanied by any side effects, and no complaints by the subjects were noted. These results may indicate a safe and efficient use of Ala-Gln as source of free glutamine in parenteral nutrition.

Parenteral nourishment of patients undergoing surgical or traumatic stress

Severe surgical or other traumatic stress initiates an integrated central nervous system and metabolic response characterized by catabolism which selectively preserves vital organs, drawing on peripheral tissue proteins for required amino acids. When oral intake is prohibited adequate intravenous nutritional support hastens convalescence and may be life-saving. Intravenous nutrients routinely consist of amino acids for replacement of lost protein, a nonprotein calorie source--usually glucose, and vitamins and minerals. Lipid, infrequently used in routine surgery as part of the calorie source, supplies essential fatty acids and prevents side effects resulting with large amounts of intravenous glucose. Lipid has other benefits. Stress-induced hormones stimulate lipid catabolism. When lipid is used for part of the calorie requirement in intravenous feedings, the plasma insulin level is reduced and peripheral amino acids become available for synthesis of critically needed visceral proteins. Recent work has shown that the branched chain amino acids carnitine and some species of lipid added to intravenous nutrient formulations postoperatively affect the nitrogen retention and may hasten convalescence. Further work should be directed at understanding the unique biochemical changes occurring after injury, devising objective assay procedures to measure the severity of the response and improving intravenous formulations for the acutely ill surgical patient.