ABSTRACT Polymeric stabilizers have received attention in the preparation of nanostructured systems due to their ability to enhance formulation stability. Considering this, the objective of this work was to prepare poly(ε-caprolactone) nanocapsules using the pullulan as a polymeric stabilizer. The nanocapsules were prepared using the interfacial deposition method of preformed polymers and they were characterized in terms of pH, average diameter, polydispersity index, zeta potential, beclomethasone dipropionate content, encapsulation efficiency, photostability and drug release profiles. The formulations showed physicochemical characteristics consistent with nanocarriers for drug delivery such as: average diameter lower than 270 nm, polydispersity indexes lower than 0.2, negative zeta potential (-22.7 to -26.3 mV) and encapsulation efficiencies close to 100%. In addition, the nanocapsules were able to delay the beclomethasone dipropionate photodegradation under UVC radiation and by the dialysis bag diffusion technique, the nanocapsules were able to prolong the drug release. Thus, pullulan could be considered an interesting excipient to formulate polymeric nanocapsules.

resumo Um método simples de CLAE-FR/UV indicativo de estabilidade foi validado para a determinação do dipropionato de beclometasona (BD) em suspensões de nanocápsulas. As condições cromatográficas foram: coluna C18 fase reversa (250 mm x 4,60 mm, 5 µm, 110 Å), usando como fase móvel metanol e água (85:15 v/v) a 1,0 mL/min, com detecção UV a 254 nm. A curva de calibração foi linear no intervalo de 5,0-25,0 µg/mL com coeficiente de correlação >0,999. A precisão foi demonstrada por um desvio padrão relativo menor que 2,0%. A exatidão foi avaliada pelo teste de recuperação do BD a partir das nanocápsulas (98,03% a 100,35%). O teste de especificidade não mostrou interferência dos componentes das nanocápsulas e nem dos produtos de degradação derivados de condições ácidas, básicas e fotolíticas. Em conclusão, o método é adequado para ser aplicado na avaliação do BD puro e em nanocápsulas e pode ser empregado para o estudo de estabilidade e degradação cinética.

abstract A simple stability-indicating RP-HPLC/UV method was validated for determination of beclomethasone dipropionate (BD) in nanocapsule suspensions. Chromatographic conditions consisted of a RP C18column (250 mm x 4.60 mm, 5 µm, 110 Å), using methanol and water (85:15 v/v) as mobile phase at 1.0 mL/min with UV detection at 254 nm. The calibration curve was found to be linear in the concentration range of 5.0-25.0 µg/mL with a correlation coefficient > 0.999. Precision was demonstrated by a relative standard deviation lower than 2.0%. Accuracy was assessed by the recovery test of BD from nanocapsules (98.03% to 100.35%). Specificity showed no interference from the components of nanocapsules or from the degradation products derived from acid, basic and photolytic conditions. In conclusion, the method is suitable to be applied to assay BD in bulk drug and in nanocapsules, and it can be employed to study stability and degradation kinetics.