Development, characterization and stability of microemulsionated formulations of bacaba, Oenocarpus bacaba oil

Advances in nanotechnology, combined with the use of natural products, represent a promissing research field. Brazil is a country of a rich biodiversity, especially in the Amazon forest. Fruits commonly used by local communities, such as bacaba (Oenocarpus bacaba), are potentially important for prospection of industrial applications of natural products. In nanotechnology, microemulsions stand out for providing a modified release to conveyed substances. This work aimed to develop microemulsionated formulations of bacaba oil, characterize them and evaluate their stability. We determined the HLB (hydrophile-lipophilic balance) of bacaba oil for formulation development. Six formulations were selected from pseudoternary diagrams, which indicated the proportions of surfactants, aqueous phase and bacaba oil. The viability of these formulations was evaluated through stability tests. We provided the rheological characterization of the formulations, evaluated their potential antioxidant activity through the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging method, and determined the hydrodynamic diameter of the droplets. The microemulsions were stable throughout the test period. Droplet diameter was below 200 nm, and the microemulsions were characterized as newtonian fluids, presenting an increase in antioxidant activity when compared with the diluted oil. Our results confirm the potential of bacaba oil in microemulsionated formulation as a suitable carrier for active compounds. (AU)

Solid lipid nanoparticles of irbesartan: preparation, characterization, optimization and pharmacokinetic studies

ABSTRACT Irbesartan is an antihypertensive with limited bioavailability and solid lipid nanoparticles (SLN) is one of the approaches to improve bioavailability. Solid lipid nanoparticles were prepared using glyceryl monostearate by solvent emulsification method followed by probe sonication. Irbesartan loaded SLNs were characterized and optimized by parameters like particle size, zeta potential, surface morphology entrapment efficiency and in vitro release. The optimized formulation was then further evaluated for the pharmacokinetic studies in Wistar rats. Irbesartan-loaded SLN of particle size 523.7 nm and 73.8% entrapment efficiency showed good bioavailability in Wistar rats and also showed optimum stability in the studies. The SLN prepared using glyceryl monostearate by solvent emulsification method leads to improve bioavailability of the drug.

Formulation and characterization of self emulsifing pellets of carvedilol

The purpose of present study was aimed at developing self emulsifying drug delivery system in liquid and then in pellet form that would result in improved solubility, dissolution and permeability of the poorly water soluble drug carvedilol. Pellets were prepared using extrusion-spheronization technique incorporating liquid SEDDS (carvedilol, capmul MCM EP, cremophore EL, tween 20, propylene glycol), adsorbents ( and crospovidone), microcrystalline cellulose and binder (povidone K-30). Ternary phase diagram was constructed to identify different oil-surfactant-cosurfactant mixtures according to the proportion of each point in it. The optimal CAR-SEDDS pellets showed a quicker redispersion with a droplet size of the reconstituted microemulsion being 160.47 nm, which was almost unchanged after solidification. SEM analysis confirmed good spherical appearance of solid pellets; DSC and XRD analysis confirmed that there was no crystalline carvedilol in the pellets. Pellets were then capable of transferring lipophilic compounds into the aqueous phase and significantly enhancing its release with respect to pure drug.

O propósito do presente estudo foi desenvolver um sistema líquido de liberação de fármacos auto emulsificante e, então, na forma de pélete, que poderia resultar em aprimoramento da solubilidade, da dissolução e permeabilidade do fármaco carvedilol, pouco solúvel em água. Os péletes foram preparados utilizando-se a técnica de extrusão-esferonização, incorporando líquido SEDDS (carvedilol, capmul MCM EP, Cremofor EL, Tween 20, propileno glicol), adsorventes (e crospovidona), celulose microcristallina e ligante (povidona K-30). O diagrama de fase ternário foi construído para identificar as misturas diferentes de óleo-tensoativo-co-tensoativo, de acordo com a proporção em cada ponto delas. Os péletes CAR-SEDDS mostraram redispersão mais rápida, com tamanho de gota da microemulsão reconstituída de 160,47 nm, que se mostrou quase inalterada após a solidificação. A análise por SEM confirmou a aparência esférica dos péletes sólidos. Análise por DSC e XRD confirmou que não havia carvedilol cristalino nos péletes. Estes foram, então capazes de transferir os compostos lipofílicos para a fase aquosa, aumentando, significativamente, sua liberação em relação ao fármaco puro.

Desenvolvimento de emulsões óleo de oliva/água: avaliação da estabilidade física / Development of olive oil-in-water emulsions: assessment of physical stability

Emulsões óleo de oliva/água, na presença de agentes emulsionantes não-iônicos, foram avaliadas quanto à estabilidade física. Assim, prepararam-se emulsões fazendo uso de diferentes emulsionantes, sendo um hidrofílico e o outro lipofílico, nas diferentes proporções. Às emulsões mais estáveis, adicionaram-se agentes auxiliares da emulsificação, visando otimizar a estabilidade; e estudos de estabilidade foram conduzidos, submetendo as amostras em condições e períodos diversos de armazenamento. Para caracterização da estabilidade, as amostras foram examinadas macroscopicamente e submetidas às análises de pH, centrifugação, viscosidade, potencial zeta e distribuição de tamanho de partícula. Os resultados demonstraram que as emulsões óleo de oliva/água não apresentaram alteração, ou seja mantiveram-se estáveis, quanto às propriedades organolépticas, bem como físicoquímicas, quando armazenadas à temperatura ambiente e protegidas da luz. Das emulsões obtidas, as que apresentaram maior estabilidade provêm da associação de agentes emulsionantes que resultaram em equilíbrio hidrofílico-lipofílico (EHL) equivalente a 12. As emulsões provenientes da associação de agentes emulsionantes que possuem cadeias de ácidos graxos insaturados similares ao óleo de oliva produziram estabilidade máxima, demonstrando que a similaridade estrutural entre os componentes da fase oleosa e os agentes emulsionantes é essencial para a estabilidade da emulsão.

Olive oil-in-water emulsions, developed with non-ionic emulsifiers, were assessed with regard to physical stability. Emulsions were prepared with two different emulsifiers, one of which was hydrophilic and the other lipophilic, in various proportions. To improve emulsion stability, auxiliary emulsifiers were added to the stablest emulsions and stability studies were carried out, in which the samples were stored for different periods and under various conditions. To test emulsion stability, the samples were examined macroscopically and various physicochemical properties, such as pH, centrifugation, viscosity, zeta potential and particle size distribution, were assessed. The results showed that olive oil-in-water emulsions are organoleptically and physicochemically stable, when stored at room temperature and protected from the light. Out of the emulsions developed, the most stable was based on an emulsifier blend that resulted in a hydrophilic-lipophilic balance (HLB) of 12. A blend of emulsifiers with unsaturated fatty acids of similar chain length to that of olive oil produced the stablest emulsions, showing that structural similarity between the hydrocarbon moieties of the oil phase and the surfactant is essential to successful emulsion stabilization.