Development and evaluation of multiparticulate biphasic system for the treatment of circadian diseases

Multiparticulate systems have biopharmaceutical advantages when compared to the monolithic systems, once they allow different patterns of drug release and can be used in different treatments. The aim of the present work was to develop a biphasic controlled release delivery system, using propranolol hydrochloride (PROP) that can be used for the treatment of circadian diseases. This system was obtained by the combination of cellulosic polymers hydroxypropyl methylcellulose (HPMC) and ethylcellulose (EC) in a 2² factorial experimental design, which allowed the optimization of the development stage. The pellets produced and used in biphasic formulations were evaluated for physical and chemical characteristics and presented acceptable results. The immediate fraction obtained showed the complete release in 30 min while the others kept the release of the drug for 24 h. This study showed that the combination of beads with different releasing characteristics allowed to obtain different release profiles, which can be modulated according to the pathological needs, especially with regard to circadian diseases that suffer alterations throughout the day.

Degradação fotocalítica de bentazona com TiO2 / Photocatalytical degradation of bentazone with TiO2

Este estudo avaliou a degradação oxidativa do herbicida pós-emergente Basagran(r) 600 por fotólise e fotocatálise, usando TiO2 como catalisador, comparando-se a eficiência de ambos os processos. Os experimentos foram realizados irradiando-se soluções aquosas do herbicida em um reator do tipo slurry. Os tratamentos foram acompanhados por espectrofotometria de absorção na região do UV-visível observando-se a banda centrada em 335 nm. O primeiro processo mostrou-se pouco efetivo, sendo observada mínima redução dos valores de absorvância. Já o segundo foi muito mais eficiente, sendo observado, após 270 min de irradiação, 100% de redução da absorvância da banda no comprimento de onda estudado. Este processo seguiu uma cinética de pseudo-primeira ordem e teve constante de velocidade (k) estimada de 0,0116 min-1.

This study evaluated the oxidative degradation of the post-emerging herbicide Basagran(r) 600 by photolysis and photocatalysis using TiO2 as catalyst, and both processes were compared in their efficiency. The experiments were done irradiating aqueous solutions of the herbicide in a slurry type reactor. The treatments were accompanied by spectrophotometry in the UV-visible range observing the band centered in 335 nm. The first process showed rather ineffective, being observed minimal reduction of the absorbance values. On the other hand, the second process was much more efficient, being observed, after 270 min of irradiation, 100% absorbance reduction of the band in the choose wavelength. This process followed pseudo-first-order kinetic and the estimated rate constant (k) was 0.0116 min-1.