Micropartículas de poli(3-hidroxibutirato-co-3-hidroxivalerato) (PHBV) contendo um fármaco modelo hidrofílico, o cloridrato de metformina (MH), foram obtidas pela técnica de emulsão múltipla/evaporação do solvente. Diversas formulações foram preparadas, com o objetivo de investigar a influência de cada composição sobre a eficiência de encapsulação (EE). O resultado mais elevado de EE (9,76%) foi verificado quando da simultânea alcalinização e adição de NaCl na fase aquosa externa da formulação. O estudo por MEV das micropartículas revelou morfologia esférica e superfície rugosa. As intensidades de difração cristalina para as micropartículas contendo o MH foram menores do que aquelas observadas para a mistura física. Os resultados obtidos por IVTF sugerem que nenhuma ligação química foi formada entre o polímero e o fármaco. A avaliação por análise térmica indica o surgimento de interações favoráveis entre MH e PHBV. O estudo de liberação in vitro demonstrou a influência do PHBV no perfil de dissolução do MH.Poly(3-hydroxybutirate-co-3-hydroxyvalerate) (PHBV) microparticles containing a watersoluble model drug, metformin hydrochloride (MH), were obtained by a double emulsion/solvent evaporation technique. Several formulations were prepared in order to investigate the influence of each composition on the encapsulation efficiency (EE). The highest value of EE (9.76%) was obtained using simultaneously pH alkalinization and NaCl addition in the external water phase of the formulation. SEM study revealed a spherical morphology and a rough surface. The crystalline diffraction intensities for the MH-loaded microparticles were lower than that verified for the physical mixture. FTIR results suggested that no chemical bond between the polymer and the drug was formed. Also thermal analyses indicated a favorable interaction between MH and PHBV. In vitro drug release demonstrated the influence of the PHBV on the dissolution profile of MH. Keywords: PHBV, double emulsion/solvent evaporation technique, hydrophilic model drug, microparticles IntroductionBiodegradable polymeric materials have been received increasing interest due to several ecological and recycling aspects. 1,2 Among numerous microbial polyesters, poly(3-hydroxybutirate-co-3-hydroxyvalerate) (PHBV) has been widely investigated as a biocompatible material suitable for pharmaceutical and medical applications. The literature reports the use of PHBV in tissue engineering and as drug delivery systems. [3][4][5][6][7][8][9][10][11][12] Particularly, PHBV exhibits unique and interesting physicochemical features (e.g. piezoelectricity) in addition to their mechanical properties similar to the polypropylene and other widely used polyesters [e.g. poly(DL-lactide) and poly(DL-lactide-co-glycolide)]. 13 Moreover, PHBV is a less crystalline biopolymer than poly(3-hydroxybutirate), therefore an enhanced degradation rate is observed. 14 Farago et al. 1299 Vol. 19, No. 7, 2008 Several methods have been used to prepare microparticles, for both natural and synthetic polymers. 15...

The aim of the present study was to develop a transdermal system for controlled delivery of melatonin combining three strategies: nanoencapsulation of melatonin, drying of melatonin-loaded nanocapsules, and incorporation of nanocapsules in a hydrophilic gel. Nanocapsules were prepared by interfacial deposition of the polymer and were spray-dried using water-soluble excipients. In vitro drug release profiles were evaluated by the dialysis bag method, and skin permeation studies were carried out using Franz cells with porcine skin as the membrane. The use of 10% (w/v) water-soluble excipients (lactose or maltodextrin) as spray-drying adjuvants furnished redispersible powders (redispersibility index approximately 1.0) suitable for incorporation into hydrogels. All formulations showed a better controlled in vitro release of melatonin compared with the melatonin solution. The best controlled release results were achieved with hydrogels prepared with dried nanocapsules (hydrogels > redispersed dried nanocapsules > nanocapsule suspension > melatonin solution). The skin permeation studies demonstrated a significant modulation of the transdermal melatonin permeation for hydrogels prepared with redispersible nanocapsules. In this way, the additive effect of the different approaches used in this study (nanoencapsulation, spray-drying, and preparation of semisolid dosage forms) allows not only the control of melatonin release, but also transdermal permeation.

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Flavonoids are among the most important plant metabolites. Due to their potential benefits, there is a considerable interest in this natural product. In genus Citrus, some plants have not yet been much exploited in Brazil, as in the case of grapefruit (Citrus maxima), whose main flavonoids are naringin and their aglycone naringenin. The physico-chemical characteristics are important pre-requisites of reference chemical in future studies. In this context, the objective of this study was to determine the characterization of naringin and naringenin by melting point, DSC, UV-VIS, 1H and 13C NMR, IR and MS. Results revealed that, naringin and naringenin after characterization, can be used as a chemical of reference in future studies and contribute to seeking possible technological applications.