Regular ArticleRecently, attention has been paid to lecithin/chitosan nanoparticles (NPs) as an alternative colloidal carrier system to polymeric nanoparticles, solid lipid nanoparticles, liposomes and nanoemulsions. These nanoparticles were obtained from the supra-molecular self-organising interaction of the negatively charged lipid material lecithin and the positively charged polysaccharide chitosan, without preliminary vesicle formation.1,2) These constitutive materials are favoured due to their well-known characteristics: Chitosan is a biocompatible and biodegradable cationic polysaccharide exhibiting bioadhesive and penetration enhancing properties 3) ; lecithin is a natural lipid mixture of phospholipids, mainly phosphatidylcholine and phosphatidylethanolamine, and is considered a safe and biocompatible excipient that has been frequently used for the preparation of various delivery nanosystems, such as micro-and nanoemulsions, 4) liposomes, 5) micelles 6) and solid lipid nanoparticles. 7)Mucoadhesive lecithin/chitosan NPs were shown to be suitable carriers for lipophilic drugs. NP suspension prepared with Lipoid S45 lecithin with a lecithin-to-chitosan weight ratio of 20 : 1 enhanced melatonin permeability through a Caco-2 cell monolayer compared to its permeability in an aqueous solution, without inducing plasma membrane damage or a decrease in cell viability at the concentration tested. 8) In another study, lecithin/chitosan NP dispersion was shown to increase accumulation of clobetasol-17-propionate in the skin without any significant permeation across the skin, compared to chitosan gel and commercial cream. 9)These findings imply that lecithin/chitosan NPs have great potential to improve the permeation of encapsulated drugs across various biological barriers. However, the overall poor stability of colloidal nanoparticles in an aqueous medium is a significant drawback from a development perspective. Thus, one of the most important challenges in the development of nanoparticles is to achieve long-term stability during storage.Freeze-drying is a well-established approach to increase the chemical and physical stability of colloidal systems over extended time periods. Prior to the freeze-drying process, special excipients are usually added to the formulation to protect the nanoparticles from various stresses generated during the freezing and drying steps. The role of sugars, such as sorbitol, mannitol, trehalose, glucose, sucrose, and lactose, as lyoprotective and/or cryoprotective agents to prevent nanoparticle aggregation and improve the redispersibility of the dry product has been reviewed in the literature. 10) Briefly, stabilisation of materials in sugar glasses has been explained by the formation of a glassy sugar matrix, which acts as a physical barrier between the particles 11) and inhibits diffusion on a relevant time scale. 12) Recently, Zhang et al. reported that sugars such as glucose and trehalose are very effective in preventing particle aggregation and inhibiting leakage of an active ingredie...

Spray dried microparticles containing mupirocin calcium were designed as acrylic matrix carriers with modulated drug release for efficient local drug delivery at minimum daily dose. Particle generation in spray drying and its effect on release performance were assessed by varying drug : polymer ratios with consequently altered initial saturations. Narrow-sized microparticles with mean diameters of 1.7-2.5 µm were obtained. Properties of the generated solid dispersions were examined by X-ray, thermal (thermogravimetric analysis, modulated differential scanning calorimetry) and spectroscopic (Fourier transformed infrared, Fourier transformed Raman) methods and correlated with drug loading and in vitro release. The best control over mupirocin release was achieved for 2 : 1 (w/w) drug : polymer ratio and found to be strongly process-dependent. For a particular ratio, increased feed concentration (>4%) boosted while increased inlet temperature (≥ 100 °C) reduced drug release. Antimicrobial activity testing confirmed that encapsulated drug preserved its antibacterial effectiveness. Conclusively, spray drying was proven as a suitable method for preparing structured microparticles which can control drug release even at exceptionally high drug loadings.

Acrylic-based MP were confirmed as suitable microcarriers for prolonged drug release using a well-established spray drying technique, while solvent influence was strongly related to the DL employed.

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