Biomedical subjects

Aviram Spernath

Publications and source records attributed to Aviram Spernath.

4 recordsLinked to original sources

PubMed2007

Microemulsions as carriers for drugs and nutraceuticals.

Microemulsions are potentially excellent carriers for bioactive molecules. They offer the advantage of spontaneous formation, ease of manufacture, thermodynamic stability, and improved solubilization of bioactive materials. This review explores some of the new trends in microemulsion research through analysis of some representative studies. The solubilization of different classic drugs, peptides, and nutraceuticals in various oral microemulsion compositions and microstructures was reviewed. It was found that even W/O microemulsions, which are expected to break upon dilution in the digestive tract, increase the permeability and bioavailability of drugs. Thus, it seems that component selection (the use of molecules that can act as permeability enhancers) is of great importance. Structures such as self-microemulsifying drug delivery systems (SMEDDS), W/O, bicontinuous, and O/W microemulsions, were closely examined, and their potential to serve as drug carriers was evaluated. It seems that for microemulsion systems to be used as vehicles for bioactive materials, the formulations should be based on SMEEDS, which form O/W upon dilution to a specific water content. U-type microemulsions are actually an improved SMEDDS formulation, capable of being diluted with any given water concentration. Much research is being conducted on microemulsion microstructure since there is an obvious direct connection between the microstructure, solubilization capacity, and bioavailability of the active molecules.

Absorption↗

PubMed2006

Fully dilutable microemulsions embedded with phospholipids and stabilized by short-chain organic acids and polyols.

Evidence on the role of phosphatidylcholine (PC) as a membrane permeability enhancer was the driving force in forming new liquid nanosized (modified microemulsions) oral delivery system containing PC molecules. In this study we have demonstrated the feasibility of constructing phase diagrams with a large isotropic regions capable of being fully diluted with water. The microemulsions were stabilized with mixtures composed of PC and nonionic surfactant (polyoxyethylene-40 hydrogenated castor oil, HECO40) and short-chain organic acid as cosurfactant/cosolvent. When propionic acid served as the cosurfactant/cosolvent, the isotropic region was at its maximum (ca. 72% of the total phase diagram area). The presence of a blend of PC and HECO40 seems to have synergistic effects, forming an isotropic region comprising 72% of the area of the phase diagram, in comparison to 20 and 50% in systems stabilized by PC and HECO40, alone, respectively. The role of the PC molecules in the formation of those microemulsions is demonstrated by comparing three soy lecithins. Lecithin with a high PC content forms larger isotropic regions with more "free dilution" lines. Several nonionic surfactants have been investigated, yet only HECO40 seems to have a packing parameter suitable for the formation of large isotropic U-type systems.

Administration, Oral↗

PubMed2003

Self-diffusion nuclear magnetic resonance, microstructure transitions, and solubilization capacity of phytosterols and cholesterol in Winsor IV food-grade microemulsions.

Microemulsions are of growing interest to the food industry as vehicles for delivering and enhancing solubilization of natural food supplements with nutritional and health benefits. The incorporation of molecular phytosterols, cholesterol-lowering agents, in food products is of great interest to the food industry. In this work is demonstrated the use of water dilutable food-grade microemulsions consisting of ethoxylated sorbitan ester (Tween 60), water, R-(+)-limonene, ethanol, and propylene glycol as vehicles for enhancing the phytosterols solubilization. Phytosterols were solubilized up to 12 times more than the dissolution capacity of the oil [R-(+)-limonene] for the same compounds. The solubilization capacity of phytosterols and cholesterol along a dilution line in a pseudo-ternary phase diagram [on this dilution line the weight ratio of R-(+)-limonene/ethanol/Tween 60 is constant at 1:1:3] was correlated to the microstructure transitions along the dilution line. Structural aspects were studied by self-diffusion NMR spectroscopy. The ability of phytosterols to compete with cholesterol for penetration into bile salt micelles in the gut may be limited to rich aqueous systems (O/W microemulsion).

Cholesterol↗

PubMed2002

Food-grade microemulsions based on nonionic emulsifiers: media to enhance lycopene solubilization.

Water-dilutable food-grade microemulsions consisting of ethoxylated sorbitan esters, and in some cases blended with other emulsifiers, water, (R)-(+)-limonene, ethanol, and propylene glycol, have been prepared. These microemulsions are of growing interest to the food industry as vehicles for delivering and enhancing solubilization of natural food supplements with nutritional and health benefits. Lycopene, an active natural lipophilic antioxidant from tomato, has solubilized in water-in-oil, bicontinuous, and oil-in-water types of microemulsions up to 10 times the oil [(R)-(+)-limonene] dissolution capacity. The effects of aqueous-phase dilution, nature of surfactant (hydrophilic-lypophilic balance), and mixed surfactant on solubilization capacity and solubilization efficiency were studied. Structural aspects studied by self-diffusion NMR were correlated to the solubilization capacity, and transformational structural changes were identified.

Carotenoids↗