Development of nanocapsule suspensions and nanocapsule spray-dried powders containing melatonin

Abstract

Suspensões de nanocápsulas contendo melatonina foram preparadas pelo método de deposição interfacial e caracterizadas (tamanho, morfologia e eficiência de encapsulação). Foram avaliadas as influências do tipo de polímero, de óleo e de tensoativo sobre as características dos produtos. A eficiência de encapsulação da melatonina variou de 30% a 56% e a natureza do polímero foi o parâmetro de maior influência. De acordo com a maior eficiência de encapsulação, nanocápsulas preparadas com Eudragit S100 ® foram selecionadas para secagem por aspersão, objetivando-se aumentar a estabilidade física das suspensões e controlar a liberação da melatonina. O pó obtido apresentou eficiência de encapsulação de 93% e não sofreu nenhuma alteração morfológica após 12 meses de armazenamento. Este sistema apresentou perfil de liberação controlado, comparativamente ao fármaco puro, o qual foi ajustado ao modelo monoexponencial. O mecanismo de liberação da melatonina foi baseado em intumescimento e dissolução do polímero.Nanocapsule suspensions containing melatonin were prepared by interfacial deposition method and characterized (size, morphological aspect and encapsulation efficiency). The formulation parameters studied were the oil nature, the type of surfactants and the type of polymer. The melatonin-encapsulation efficiency ranged between 30% and 56% and polymer nature was the parameter that more influenced the characteristics of suspensions. According to the highest encapsulation efficiency, the nanocapsules prepared with Eudragit S100 ® were selected to be spray-dried in order to improve the physical stability of suspension and to control the release of melatonin. The melatonin-loaded nanocapsule spray-dried powder presented encapsulation efficiency of the 93% and no morphological alterations were observed after 12 months of storage. This system showed a controlled release profile in comparison to the dissolution of the pure melatonin. The release profile was fitted to monoexponential model and the melatonin release mechanism was based on swelling and dissolution of the polymer. Keywords: melatonin, nanocapsules, nanoparticles, spray-dried powders IntroductionMelatonin, N-acetyl-5-methoxytryptamine (Figure 1), is a hormone secreted at night-time by the pineal gland of mammals and it is involved in the regulation of the sleepwake cycle, as well as in several biological functions, such as the modulation of mood, the control of seasonal reproduction in animals, the circadian rhythm regulation, the normal patterns of sleep, 1 and the neuroimmunomodulation in humans.2 The administration of the exogenous melatonin has been employed for circadian rhythm disorders as jet-lag and insomnia. 1 Beyond the potent antioxidant activity, the melatonin is a free radical scavenger, 3 protects against lipid peroxidation in several models 4 and against oxidative stress observed in some neurodegenerative diseases such as Alzheimer.5 It also protects against ischemia/ reperfusion injury 6 and presents anti-tumor activities. 7However, melatonin has a v...

Polymeric nanoparticles loaded with the 3,5,3´-triiodothyroacetic acid (Triac), a thyroid hormone: factorial design, characterization, and release kinetics

“…All formulations presented a macroscopic homogeneous aspect like a bluish white milky opalescent fluid (Tyndall effect) as a result of the nanoparticle formation as soon as the organic phases were diffused into the aqueous phase, in agreement with results previously reported for other nanoparticle systems. 13,18 This observation confirms the formation of nanoparticles. The polymer was dissolved in a water-miscible solvent of intermediate polarity, leading to the precipitation of nanospheres (absence of oil) and nanocapsules.…”

“…A technique of the fractional factorial design 2 , to twolevel factorial design, offers the possibility of investigating eleven independent variables. The fixed variables, which are described in Table 1, were defined prior to literature review 13,18 and experimental compatibility evaluation for Triac. The dependent variables utilized to investigate the colloidal dispersion were pH, particle size, polydispersity index, and zeta potential.…”

“…These results are in accordance with previous work that applied the nanoprecipitation technique. 13,18 Particle size can have important consequences in pharmaceutical applications for nanoparticles loaded with Triac. In this case, the selection between nanocapsules or nanospheres might occur through the stability or solubility of Triac and through the Table 4 Results of the ph, particle size, zeta potential, absolute recovery, and entrapment efficiency for the 2 Abbreviations: AR, absolute recovery; EE, entrapment efficiency; exp, experiment; PS, particle size; UNC, uncertain; ζ, zeta potential.…”

Efficiency of neem oil nanoformulations to Bemisia tabaci (GENN.) Biotype B (Hemiptera: Aleyrodidae)

“…It is a cyclic polymer which contains seven unities of glucose joined in α-1,4 obtained through enzymatic degradation of the amylum (BOBBIO; BOBBIO, 2001). Another biodegradable polymer, poly-ε-caprolactone (PCL), has been studied by researchers not only in releasing systems of pharmaceutical drugs (SCHAFFAZICK et al, 2006) but also in civil building industry (ALMEIDA; FERREIRA, 2006). PCL is an aliphatic polyester obtained by polymerization of ε-caprolactone in the presence of aluminum isopropoxide (CHIELLINI; SOLARO, 1996).…”

Secondary Metabolism as a Measurement of Efficacy of Botanical Extracts: The Use of Azadirachta indica (Neem) as a Model

“…Nanocapsules are carries composed of an oil core surrounded by a polymeric wall, whereas nanospheres consist of a polymeric matrix. Both colloids are stabilized by surfactants at the particle/water interface (Schaffazick et al, 2006). Both systems, nanocapsules and nanospheres, may be employed as support to deliverycontrolled biopesticides programs or as stabilizer agents with several molecules such as azadirachtin.…”