Polyo iLactide

A lipophilic derivative of muramyl dipeptide, muramyl tripeptide cholesterol, was incorporated into poly(D, L-lactide) nanocapsules and its immunomodulating properties were assessed in vitro. The nanocapsule form was more effective than the free drug in activating rat alveolar macrophages for a cytostatic effect toward syngeneic tumor cells [857, 858]. The lipophilic compound, a peptidomimetic inhibitor, CGP 57813, of human immunodeficiency virus type 1 (HIV-1) protease, was successfully entrapped into poly(D, L-lactic acid) and pH sensitive methacrylic acid copolymers nanoparticles [859]. The intravenous administration to mice of poly(D, L-lactic acid) nanoparticles loaded with CGP 57813 resulted in a two-fold increase of the area under the plasma concentration-time curve, compared to a control solution. The passage of intact poly(D, L-lactic acid) nanoparticles across the gastrointestinal mucosa appears to be very low. Induction of macrophage no-synthase by an immunomodulator entrapped within polymeric nanocapsules was studied [860]. Gastrointestinal tolerance following intravenous and oral administration of poly(D, L-Lactide) nanocapsules containing nonsteroidal anti-inflammatory drugs were investigated [861].

The nanocapsules prepared from poly(D, L-lactide) containing a nonsteroidal anti-inflammatory drug, diclofenac, were formulated and their stability during storage at room temperature was studied [862]. The influence of some factors that could affect stability, namely, the type of oily phase used or/and its concentration, the concentrations of drug and of surfactants, was investigated. The pH of the preparation, the particle size, and the quantity of drug remaining (encapsulated and total), and polymer molecular weight were determined at intervals for up to 8 months after nano-capsule preparation.

Atovaquone and rifabutine had potential therapeutic activity against toxoplasmosis but the low water solubility of these drugs reduced their bioavailability [863]. Their formulation as a colloidal suspension of poly(D, L-lactic acid) nanocapsules increased that effectiveness. The atovaquone formulation was more stable than the rifabutine one and was injected at 15 mg/kg per day by the intragastric route to mice infected with toxoplasma gondii.

The mouse macrophage cell line RAW 264.7 was stimulated to produce nitric oxide by muramyltripeptide cholesterol included within biodegradable poly(D, L-lactide) nanocapsules [864]. The aim was to determine whether one or both of the cytokines transforming growth factor-^ (TGF-3) and interleukin -10 (IL-10) could be responsible for feedback, control seen at high concentrations.

Biodegradable C-14-poly-(D, L-lactic acid) [PLA(50)] nanoparticles coated either with a readily digestible protein albumin or with a nondigestible coating agent, polyvinyl alcohol (PVA), were prepared by the solvent evaporation technique [865]. The nanoparticles were administered perorally to guinea pigs to evaluate the gastrointestinal degradation of their PLA(50) matrix. In the case of PLA(50) nanoparticles coated with digestible albumin, substantial gastrointestinal degradation of the PLA(50) matrix occurred, leading to the passage of a considerable amount (greater than or equal to 45%) of water-soluble products across the gastrointestinal barrier.

The benzathine penicillin G nanoemulsion and nano-capsules were formulated, their physicochemical and stabilizing characteristics were evaluated, and their antimicrobial activity and penicillin in vitro release kinetics were determined [866]. Nanoemulsions were produced by the spontaneous emulsification approach and nanocapsules of poly(D, L-lactic acid-co-glycolic acid) (PLGA) polymer were prepared by the method of interfacial deposition of a preformed polymer.

Several formulations of poly(e-caprolactone) (PCL), PLA, and PLGA nanocapsules containing phenylbutazone were prepared according to the interfacial deposition technique [867]. These formulations differed in the type of polymer used to form the shell of the nanocapsules. Analysis of particle size distribution and encapsulation efficiency of the nanocapsules revealed that the type and molecular weight of polyester used were the main factors influencing these properties. PLA had the highest encapsulation efficiency with the best reproducibility.

The loading capacity of pentamidine-loaded poly(D, L-lactide) nanoparticles, the factors influencing pentamidine release, and the cytotoxicity of nanoparticles prepared by nanoprecipitation method were reported [868]. Various concentrations of pentamidine base and polymer were tested. The influence of the dilution, temperature, and ionic strength was evaluated. A nonlinear increase in drug uptake per unit mass of polymer with the equilibrium pentamidine concentration was found.

The interactions of naked and surface-modified PLA nanocapsules, where PEG was adsorbed or covalently attached, were studied with a macrophage-like cell line [869]. The fluorescent oil marker, DID, was successfully encapsulated in nanocapsules in order to follow their interactions with cells. The cell-associated fluorescence obtained with PEG-PLA nanocapsules was about 3 to 13-fold lower than that obtained with naked-PLA nanocapsules.

The poly(D, L-lactide) nanocapsules containing bovine serum albumin were prepared by means of a modified w/o/w double-emulsion technology [870]. A mixture of glycerin and water was used instead of the traditional stabilizer system in the preparation of polymeric nanocapsules. The results showed that the high viscosity of the mixture and the hydroxyl group of the glycerin were helpful in the formation of the nanocapsules. The prepared nanocapsules had a similar spherical form.

Lectin poly(lactide) microsphere conjugates specifically designed for oral administration were prepared and their activity and specificity in the presence of mucus were characterized [871]. The presence of hydroxyl or amino groups suitable for covalent coupling of lectins by the glutaralde-hyde method at the surface of the microspheres was ensured by preparing the particles in the presence of either PVA or bovine serum albumin (BSA).

Although the oral route for insulin delivery is the most convenient, directly administered oral insulin is degraded by proteolytic enzymes in the gastrointestinal (GI) tract. Polylactide was prepared in order to microcapsulate the insulin to avoid the enzymes in the GI [872]. The poor selectivity of photosensitizers for tumor tissue remains a drawback in photodynamic therapy (PDT) and could be improved by adapted formulations. The cellular uptake, localization, and phototoxicity of meta-tetra(hydroxyphenyl) chlorin (mTHPC) encapsulated in submicronic colloidal carriers were studied in macrophage-like J774 cells and EFT 29 human adenocarcinoma cells [873]. Nanocapsules with an external layer made of poly(D, L-lactic acid), PLA grafted with polyethylene glycol, PLA coated with polox-amer 188 (polox PLA NCs), and oil/water nanoemulsion were examined.

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