Glyceryl Diesters.

The Expert Panel for Cosmetic Ingredient Safety reviewed newly available studies since their original assessment in 2002, along with updated information regarding product types and concentrations of use, and confirmed that these 17 glyceryl diesters are safe as cosmetic ingredients in the practices of use and concentration as described in this report.

Spray congealing as a microencapsulation technique to develop modified-release ibuprofen solid lipid microparticles: the effect of matrix type, polymeric additives and drug-matrix miscibility.

This study aimed to achieve modified-release of ibuprofen (IBU) by encapsulation within lipid-based matrix materials [cetyl alcohol (CA), stearic acid (SA) and glyceryl dibehenate (GB)] using spray congealing to produce solid lipid microparticles (SLMs). Polymeric additives, polyvinyl-2-pyrrolidone-vinyl-acetate and ethylcellulose, were employed as release-modifying agents. Spray-congealed SLMs yield, scanning electron microscopy (SEM)-based morphology, particle size, drug content and entrapment efficiency were investigated. The influence of matrix type, additive type and concentration and drug-matrix miscibility on release of IBU was elucidated. Yields (81.4-96.4%) and drug encapsulation efficiencies (88.4-100%) of SLMs were high for all formulations. SLMs were generally discrete, spherical and dense. Increasing additives concentration led to not only larger median size SLMs but also faster drug release due to increased hydrophilicity conferred by the additives. Solid solution systems (SA-IBU, GB-IBU) sustained the release of IBU better than solid dispersion system (CA-IBU). CA- and GB-based SLMs closely adhered to the Weibull model of drug release, while SA counterparts followed the Korsmeyer-Peppas model.

Advanced Chemical and Imaging Methods for Studying Structure Morphology and Excipients Solid State Transformations in Pharmaceutical Multiparticulate Formulations.

The formulation of paediatric medicines faces significant challenges to meet the requirements for safe and accurate administration, while maintaining a suitable taste. Multiparticulate formulations have a strong potential to address these challenges because they combine dose flexibility with ease of administration. Understanding the stability of multiparticulate formulations over storage as a function of time and environmental parameters, such as humidity and temperature, is important to manage their commercialisation and use. In this work, we have expanded the toolkit of available techniques for studying multiparticulates beyond those such as scanning electron microscopy (SEM) and confocal laser scanning microscopy. We include advanced methods of environmentally-controlled SEM to monitor temperature- and humidity-induced changes in-situ, and a variety of Raman spectroscopies including stimulated Raman scattering microscopy to identify and localise the different ingredients at the surface and inside the multiparticulates. These techniques allowed unprecedented monitoring of specific changes to the particulate structure and distribution of individual ingredients due to product aging. These methods should be considered as valuable novel tools for in-depth characterisation of multiparticulate formulations to further understand chemical changes occurring during their development, manufacturing and long-term storage. We envisage these techniques to be useful in furthering the development of future medicine formulations.

Evaluation of the digestibility of solid lipid nanoparticles of glyceryl dibehenate produced by two techniques: Ultrasonication and spray-flash evaporation.

OBJECTIVE: To evaluate the digestibility of Solid Lipid Nanoparticles (SLN) of glyceryl dibehenate prepared either with surfactants by ultrasonication or without surfactant by spray-flash evaporation. METHODS: SLN of glyceryl dibehenate (Compritol® 888 ATO) were produced by two processes: (i) high-shear homogenization with a solution of water-soluble surfactants followed by ultrasonication (ii) and Spray-Flash Evaporation (SFE) of the pure lipid. The digestibility of these nanoparticles was then tested by in vitro lipolysis using a pH-stat apparatus and the assay of glycerides by gel phase chromatography. RESULTS: SLN of glyceryl dibehenate prepared by ultrasonication exhibited a mean particle size of 180nm and showed a limited digestion of the lipid excipient. SLN comprising only glyceryl dibehenate produced by SFE have a mean particle size between 235 and 411nm depending on process parameters. These nanoparticles were not digested by lipases. The presence of surfactant at the lipid/water interface of the SLN seems to be mandatory to allow the adsorption of the lipase and degradation of glyceryl behenate. CONCLUSIONS: Glyceryl dibehenate as a solid particle - even as a SLN - is not digested by pancreatin during in vitro lipolysis test.

In silico simulation of niacin release from lipid tablets: theoretical predictions and independent experiments.

A mechanistically realistic mathematical model is presented allowing for the quantification of niacin release from lipid tablets, based on glyceryl dibehenate. The systems were prepared either by direct compression or via hot-melt extrusion/grinding/compression. The model assumptions are based on a thorough physico-chemical characterization of the tablets before and after exposure to the release medium. Importantly, the model allows for the first time for the quantitative prediction of the effects of the composition, dimensions and type of preparation method of the tablets on the resulting niacin release kinetics. These quantitative theoretical model predictions were confirmed by several sets of independent experimental results. Furthermore, in silico simulations revealed the fundamental importance of limited niacin solubility within the lipid tablets: during major parts of the release periods, very steep concentration gradients exist and net vitamin flux is restricted to specific regions within the tablets.