<b>The effect of β-cyclodextrin in the photochemical stability of propranolol hydrochloride in aqueous solution<b>

Abstract

ABSTRACT. The degradation of propranolol hydrochloride (1-isopropylamino-3-(naphthoxy)-2-propranolol) in an aqueous solution was analyzed when irradiated by light UV, with and without β-cyclodextrin. There was an increase in the compound´s photostability in nanocavity when compared with the drug without the cyclodextrins' cavity. First order kinetic model was employed for the degradation of propranolol in aqueous media and in cyclodextrins' cavity. The kinetic parameter was obtained by the drug´s absorption and electronic fluorescence. As a rule, encapsulation of propranolol in β-cyclodextrin decreases photodegradation speed by 53%.Keywords: nanocavity, drug, photochemical.O efeito da β-ciclodextrina na estabilidade fotoquímica do cloridrato de propranolol em solução aquosa RESUMO. Neste trabalho, foi estudada a degradação do cloridrato de propranolol (1-isopropilamina-3-(nafitiloxi)-2-propranolol) em solução aquosa por irradiação UV na presença e ausência de β-ciclodextrina. Verificou-se o aumento da fotoestabilidade da substância na presença da nanocavidade, quando comparado com a mesma na ausência da cavidade do ciclodextrinas. Foi utilizado o modelo de cinética de primeira ordem para a degradação de propranolol em meios aquosos e na cavidade ciclodextrinas, a espectroscopia de absorção e de fluorescência eletrônica da droga foi usada para obter o parâmetro cinético. De uma maneira geral, a encapsulação do propranolol em β-ciclodextrina reduz a velocidade de fotodegradação em 53%.Palavras-chave: nanocavidade, fármaco, fotoquímica.

Development of a Hydroxypropyl-β-Cyclodextrin-Based Liquid Formulation for the Oral Administration of Propranolol in Pediatric Therapy

“…As can be seen, a clear protective effect of HPβCD against the photodegradation of PPN was observed, with a reduction in the % degraded drug after 5 h of exposition to UV(A)–UV(B) radiations by more than 50% compared to the solution containing the drug alone. This result was in agreement with Ansolin et al [ 45 ], who observed a reduction in the PPN photolysis rate thanks to its complexation with βCD as a consequence of the protection of the aromatic system of the drug by the CD nanocavity. We found that the observed protective effect of the drug was more evident during the whole exposition time for the 1:2 drug:HPβCD systems, i.e., when a higher amount of HPβCD was present in the solution.…”

“…The final value of the degradation constant of PPN in the aqueous solution in the absence of HPβCD (−0.0891 min −1 ) was in agreement with Ansolin et al [ 45 ] (−0.0860 min −1 ). As can be seen, a strong reduction in the drug degradation rate was obtained in the presence of HPβCD, and this effect was more evident in the samples containing higher amounts of CD (1:2 vs. 1:1 mol/mol systems).…”

“…Degradation constants of propranolol•HCl (PPN) in the aqueous solutions containing the free drug or its 1:1 or 1:2 mol/mol physical mixture (PM) or co-ground product (GR) with HPβCD calculated after 1 h and 5 h of exposure to UV(A)-UV(B) radiations and % stabilization. The final value of the degradation constant of PPN in the aqueous solution in the absence of HPβCD (−0.0891 min −1 ) was in agreement with Ansolin et al [45] (−0.0860 min −1 ). As can be seen, a strong reduction in the drug degradation rate was obtained in the presence of HPβCD, and this effect was more evident in the samples containing higher amounts of CD (1:2 vs. 1:1 mol/mol systems).…”

“…Storage stability studies were performed on aqueous solutions at 0.2% w / v drug alone or as 1:1 or 1:2 mol:mol PM or GR systems with HPβCD to be able to investigate the influence of the CD presence on the drug stability and exclude any possible destabilizing effects. In fact, although most studies revealed a favorable effect of CD complexation on drug stability [ 32 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ], few reports about a catalytic effect of CDs on the drug degradation rate have been reported [ 61 , 62 ]. The stability studies were carried out at three different temperatures: refrigerated (4 °C), ambient (25 °C, climatic Zones I and II), and accelerated conditions (40 °C).…”

“…Although its primary and effective use is to enhance the aqueous solubility of poorly soluble drugs [ 29 , 30 , 31 ], cyclodextrin (CD) complexation proved to be an interesting tool to mask the unpleasant taste of drugs [ 32 , 33 , 34 , 35 , 36 , 37 , 38 ], as well as improve their chemical stability [ 3 , 39 , 40 , 41 ], including photostability [ 42 , 43 , 44 , 45 ]. The excellent safety profile of orally administered CDs [ 29 ] when considering their very low oral bioavailability (0.1–3%) [ 46 ] make them valuable excipients in pediatric formulations.…”