http://europepmc.org/articles/PMC1300937?pdf=render

Effect of Chain Length and Unsaturation on Elasticity of Lipid Bilayers

Since their discovery in the 1960s, liposomes have been studied in depth, and they continue to constitute a field of intense research. Liposomes are valued for their biological and technological advantages, and are considered to be the most successful drug-carrier system known to date. Notable progress has been made, and several biomedical applications of liposomes are either in clinical trials, are about to be put on the market, or have already been approved for public use. In this review, we briefly analyze how the efficacy of liposomes depends on the nature of their components and their size, surface charge, and lipidic organization. Moreover, we discuss the influence of the physicochemical properties of liposomes on their interaction with cells, half-life, ability to enter tissues, and final fate in vivo. Finally, we describe some strategies developed to overcome limitations of the "first-generation" liposomes, and liposome-based drugs on the market and in clinical trials.

https://www.dovepress.com/getfile.php?fileID=23533

Liposomes as nanomedical devices

Liposomes are the first nano drug delivery systems that have been successfully translated into real-time clinical applications. These closed bilayer phospholipid vesicles have witnessed many technical advances in recent years since their first development in 1965. Delivery of therapeutics by liposomes alters their biodistribution profile, which further enhances the therapeutic index of various drugs. Extensive research is being carried out using these nano drug delivery systems in diverse areas including the delivery of anti-cancer, anti-fungal, anti-inflammatory drugs and therapeutic genes. The significant contribution of liposomes as drug delivery systems in the healthcare sector is known by many clinical products, e.g., Doxil®, Ambisome®, DepoDur™, etc. This review provides a detailed update on liposomal technologies e.g., DepoFoam™ Technology, Stealth technology, etc., the formulation aspects of clinically used products and ongoing clinical trials on liposomes.

Liposomal formulations in clinical use: An updated review

Ethosomes — novel vesicular carriers for enhanced delivery: characterization and skin penetration properties

Encapsulation involves the incorporation of food ingredients, enzymes, cells or other materials in small capsules. Applications for this technique have increased in the food industry since the encapsulated materials can be protected from moisture, heat or other extreme conditions, thus enhancing their stability and maintaining viability. Encapsulation in foods is also utilized to mask odours or tastes. Various techniques are employed to form the capsules, including spray drying, spray chilling or spray cooling, extrusion coating, fluidized bed coating, liposome entrapment, coacervation, inclusion complexation, centrifugal extrusion and rotational suspension separation. Each of these techniques is discussed in this review. A wide variety of foods is encapsulated--flavouring agents, acids bases, artificial sweeteners, colourants, preservatives, leavening agents, antioxidants, agents with undesirable flavours, odours and nutrients, among others. The use of encapsulation for sweeteners such as aspartame and flavours in chewing gum is well known. Fats, starches, dextrins, alginates, protein and lipid materials can be employed as encapsulating materials. Various methods exist to release the ingredients from the capsules. Release can be site-specific, stage-specific or signalled by changes in pH, temperature, irradiation or osmotic shock. In the food industry, the most common method is by solvent-activated release. The addition of water to dry beverages or cake mixes is an example. Liposomes have been applied in cheese-making, and its use in the preparation of food emulsions such as spreads, margarine and mayonnaise is a developing area. Most recent developments include the encapsulation of foods in the areas of controlled release, carrier materials, preparation methods and sweetener immobilization. New markets are being developed and current research is underway to reduce the high production costs and lack of food-grade materials.

/pdf/encapsulation-in-the-food-industry-a-review-5fceoudsmh.pdf

Encapsulation in the food industry: a review

Part 1 Introduction, R.R.C.New preparation of liposomes, R.R.C.New liposome characterization, R.R.C.New covalent attachment of proteins to liposomes, F.J.Martin physical methods of study, G.R.Jones and A.R.Cossins liposomes in biological systems, R.R.C.New et al. Appendices: miscellaneous methods manufacturers and suppliers standard texts of liposomes and phospholipid membranes.

Liposomes : a practical approach

Hydrophobic preparations which are useful as, among other things, pharmaceutical delivery systems comprise: (i) an oil phase comprising one or more medium chain monoglycerides, such as Akoline MCMTM; (ii) at least one amphiphile, preferably including a phospholipid such as phosphatidyl choline; and (iii) a hydrophilic species, which may be a protein such as insulin or calcitonin or another macromolecule, solubilised or otherwise dispersed in the one or more glycerides. (The hydrophilic species is one that is not normally soluble in the glycerides).

Hydrophobic preparations containing medium chain monoglycerides

Aim: Randomized, open, single-centre, two-way crossover study comparing the pharmacokinetic (PK) and pharmacodynamic (PD) properties of subcutaneous (sc) regular human insulin (Actrapid) and oral insulin in a capsule form (Capsulin).

Methods: Sixteen persons (12 males) with type 2 diabetes on oral hypoglycaemic agents (OHAs) participated. Mean (s.d.) age 60.2 (5.5) years, BMI 28.3 (3.4) kg/m2, haemoglobin A1c (HbA1c) 7.4% (1.1). Two 6-h isoglycaemic glucose clamp studies were conducted 11 days apart. All subjects received in random order 12U sc Actrapid on one clamp study day and either 150U or 300U Capsulin (Cap) on the other day. Glucose infusion rates (GIRs), plasma insulin and C-peptide concentrations were determined throughout each 6-h isoglycaemic clamp. Between the clamp study days, all patients received 150U Capsulin twice daily, dropping all their standard OHAs apart from metformin. Self-monitored blood glucose (SMBG) levels were taken four times a day between the clamp study days.

Results: Administration of either Actrapid or Capsulin (150 and 300U) increased GIRs reaching a maximum values at approximately 280–330 min. Overall values for maximum GIR values were higher for Actrapid than either dose of Capsulin (p < 0.05). The significantly greater systemic insulin concentrations following Actrapid were reflected in the AUC0–6 h (910 ± 270 vs. 472 ± 245 pmol h/L; 950 ± 446 vs. 433 ± 218 pmol h/L; both p < 0.05 for Actrapid vs. 150U Capsulin and 300U Capsulin respectively). No difference was observed between 150U and 300U Capsulin. During the repeat-dosing period, good safety and tolerability were observed with Capsulin, and SMBG levels remained stable. At the poststudy visit, significant falls in HbA1c, weight and triglycerides were observed.

Conclusions: Administration of the oral insulin Capsulin preparation demonstrated a significant hypoglycaemic action over a period of 6 h associated with only a small increase in circulating plasma insulin concentrations.

Roger New

Papers

Liposomes : a practical approach

Hydrophobic preparations containing medium chain monoglycerides

The glucose lowering effect of an oral insulin (Capsulin) during an isoglycaemic clamp study in persons with type 2 diabetes

Reverse micelle-encapsulated recombinant baculovirus as an oral vaccine against H5N1 infection in mice

Solubilisation of hydrophilic drugs in oily formulations