Nanocapsules formulation

Tewa-Tagne, P., Briangon, S. Fessi, H. (2006). Spray-dried microparticles containing polymeric nanocapsules Formulation aspects, liquid phase interactions and particles characteristics. International Journal of Pharmaceutics, Vol. 325, 1-2, (November 2006), pp. (63-74), ISSN 0378-5173... 

Phase B aqueous phase consisting of phosphate saline buffer (pi I 7.4) and dsDNA (if any) Fig-1 Schematic representation of the PBCA nanocapsules formulation process in miniemulsion... 

J. M. Irache, M. Berrabah, P. Verite, and S. Menager, Phenobarbitone-loaded poly-curly epsilon-caprolactone nanocapsules In vitro kinetics and in vivo behaviour by the oral route, in Formulation of Poorly-Available Drugs for Oral Administration, Paris, 1996, pp. 334-337. 

The procedure chosen for the preparation of lipid complexes of AmB was nanoprecipitation. This procedure has been developed in our laboratory for a number of years and can be applied to the formulation of a number of different colloidal systems liposomes, microemulsions, polymeric nanoparticles (nanospheres and nanocapsules), complexes, and pure drug particles (14-16). Briefly, the substances of interest are dissolved in a solvent A and this solution is poured into a nonsolvent B of the substance that is miscible with the solvent A. As the solvent diffuses, the dissolved material is stranded as small particles, typically 100 to 400 nm in diameter. The solvent is usually an alcohol, acetone, or tetrahydrofuran and the nonsolvent A is usually water or aqueous buffer, with or without a hydrophilic surfactant to improve colloid stability after formation. Solvent A can be removed by evaporation under vacuum, which can also be used to concentrate the suspension. The concentration of the substance of interest in the organic solvent and the proportions of the two solvents are the main parameters influencing the final size of the particles. For liposomes, this method is similar to the ethanol injection technique proposed by Batzii and Korn in 1973 (17), which is however limited to 40 mM of lipids in ethanol and 10% of ethanol in final aqueous suspension. 

Calvo et al. [63] studied ehitosan (CS)- and poly-L-lysine (PLL)-eoated poly-e-caprolactone (PECL) nanocapsules for oeular application. In comparison with commercial eye drops, the systems investigated (uncoated, PLL-coated, and CS-coated nanocapsules) significantly increased the eoneentrations of indomethacin in the cornea and aqueous humor of rabbit eyes. The ehitosan-eoated formulation doubled the ocular bioavailability of indomethacin over the uncoated partieles, whereas the PLL coating was ineffective. The authors eoneluded that the speeifie nature of CS was responsible for the enhaneed indomethaein uptake and not the positive surfaee eharge. Both the PLL- and CS-eoated nanoeapsules displayed good oeular toleranee [63]. 

Santos-Magalhaes et al. [27] reported on PLGA nanocapsules/nanoemulsions for benzathine pencillin G. Nanoemulsions were produced by spontaneous emulsification and nanocapsules by interfacial deposition of the pre-formed polymer. They have observed similar release kinetics from both formulations [27]. 

The crosslinking of starch at the droplet interface in inverse miniemulsion leads to the formation of hydrogels. The formulation process for the preparation of crosslinked starch capsules in inverse miniemulsion is schematically shown in Fig. 10. The influence of different parameters such as the amount of starch, surfactant P(E/B-fe-EO), and crosslinker (2,4-toluene diisocyanate, TDI) on the capsule size and stability of the system were studied. The obtained capsules were in a size range of 320-920 nm. Higher amounts of starch and surfactant result in a smaller capsule size. The TEM images of crosslinked starch capsules prepared with different amount of crosslinker (TDI) are presented in Fig. 11. The nanocapsules can be employed as nanocontainers for the encapsulation of dsDNA molecules with different lengths [114] and for the encapsulation of magnetite nanoparticles. 

Cytotoxicity The cytotoxicity of nanocapsules was investigated against L929 mouse fibroblast cells and human polymorphonuclear PMNC cells with MTT assay [90], Cell viability values of different nanocapsule and nanosphere formulations on L929 and PMNC cells indicated that nonsurfactant P-CDC6 nanocapsules were less cytotoxic than nanocapsules containing surfactants. The cytotoxicity of the nanoparticles mostly arises from surfactant presence and was concentration dependent [90]. 

Losa, C. Marchal-Heussler, L. Orallo, F. Vila Jato, J.L. Alonso, M.J. Design of new formulations for topical ocular administration polymeric nanocapsules containing metipranolol. Pharm. Res. 1993,10, 80-87. 

In pharmaceutical preparations, soybean oil emulsions are primarily used as a fat source in total parenteral nutrition (TPN) regimens. Although other oils, such as peanut oil, have been used for this purpose, soybean oil is now preferred because it is associated with fewer adverse reactions. Emulsions containing soybean oil have also been used as vehicles for the oral and intravenous administration of drugs drug substances that have been incorporated into such emulsions include amphotericin, " diazepam, retinoids, vitamins, poorly water-soluble steroids, fluorocarbons, and insulin. In addition, soybean oil has been used in the formulation of many drug delivery systems such as liposomes, microspheres, dry emulsions, self-emulsifying systems, and nanoemulsions and nanocapsules. ... 

CDC are defined only by their size (most scientists agree on sizes below 1 pm others set 0.5 pm as the upper limit). CDC are very heterogeneous in all other aspects (e.g., thermodynamic stability, chemical composition, and the physical state, including solid, liquid, or liquid-crystalline dispersions) [ 1 ]. The most prominent examples are nanoparticles, nanoemulsions, nanocapsules, liposomes, nanosuspensions, (mixed) micelles, microemulsions, and cubosomes. Some CDC have reached the commercial market. Probably the best known example is the microemulsion preconcentrate of cyclosporine (Sandimmun-Neoral), which minimized the high variability of pharmacokinetics of the Sandimmun formulation. In addition, intravenous injectable CDC have been on the commercial market for many years. Examples include nanoemulsions of etomidate (Etomidat-Lipuro) and diazepam (Diazepam-Lipuro) [2-4], mixed micelles (Valium-MM, Konakion), and liposomes (AmBisome) [5]. 

Watnasirichaikul, S., Rades, T., Tucker, I.G. and Davies N.M. (2002) Effects of formulation variables on characteristics of poly (Ethylcyanoacrylate) nanocapsules prepared from W/O microemulsions. Int. ]. Pharm., 235, 237-246. 

Nanocapsules can be formulated from a variety of synthetic or natural monomers or polymers by using different techniques in order to fulfil the requirements of various applications. Both, hydrophobic and hydrophilic liquids are of high interest for encapsulation. So, e.g., either sensitive or volatile substances, as drugs or fragrances have to be encapsulated and protected for applications with a sustained demand of the respective compound. DNA, proteins, peptides or other active substances can be encapsulated in order to target them to specific cells. A further benefit of the polymeric shell is the possibility to control the release from the composite particles and hence the concentration in the environment. 

Insulin loaded nanocapsules dispersed in biocompatible microemulsion resulted in significantly greater reduction in blood glucose levels than aqueous insulin solution. This demonstrated that formulation of peptides within nanoc sules administered dispersed in microemulsion can facilitate oral absorption of encapsulated peptide. Such system can be prepared in situ by the interfacial polymerization of a w/o microemulsion. 

Lv, Y, Yang, F, Xueying, L., Zhang, X., and Abbas, S. (2014). Formulation of heat-resistant nanocapsules of jasmine essential oil via gelatine/gum Arabic based complex coacervation. Food Hydrocolloids, 35, 305-314. 

Nanosuspensions consist of the pure poorly water-soluble drug without any matrix material suspended in dispersion. It is sub-micron colloidal dispersion of pure particles of drug stabilized by surfactants. By formulating nanosuspensions, problems associated with the delivery of poorly water-soluble drugs and poorly water-soluble and lipid-soluble drugs can be solved. Nanosuspensions differ from nanoparticles, " which are polymeric colloidal carriers of drugs (nanospheres and nanocapsules), and from solid-lipid nanoparticles, which are lipidic carriers of drug. 

For ophthalmic applications, properly formulated drug-loaded nanoparticles (DNPs) are reported to provide ease of application just like eye drop solutions, with the added advantage of being patient friendly, due to less frequent application and extended duration of retention in the extraocular portion. The drug may be attached to a nanoparticle matrix, or dissolved, encapsulated, and entrapped, giving rise to different terminologies as nanoparticles, nanospheres, or nanocapsules. " ... 

In the development of our self-healing epoxy resins, the evaluation of the catalytic activity was investigated for the epoxy matrix (formulation without nanocapsules). 

A detailed study of the influence of nanocapsules with a multilayer shell on cell viability and cell penetration ability was very recently presented by Lukasiewicz and Szczepanowicz. Poly(L-lysine) polycations and poly(L-glutamic acid) polyanions were used to build the capsule walls and the PEG-ylated outer layer was introduced to render the system biocompatible. The authors showed the influence of the number of layers, surface charge, and the presence of outer PEG-ylated layer on the cytotoxicity of the formulation. An increase in a number of layers and positive surface charge led to a stronger negative effect on the cells, while PEG-ylation of the outer layer was beneficial. Interestingly, such PEG-modified nanocapsules were easily internalized by human embryonic kidney 293 (HEK 293) cells. 

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