ABSTRACT The Maillard reaction of hydrochlorothiazide (HCTZ) and lactose has been previously demonstrated in pharmaceutical formulations. In this study, the activation energy of - hydrohlorothiazide and lactose interaction in the liquid state was ascertained under basic and neutral conditions. Conventional isothermal High Performance Liquid Chromatography (HPLC) technique was employed to ascertain the kinetic parameters using Arrhenius method. Results: The activation energy obtained was 82.43 and 100.28 kJ/mol under basic and neutral conditions, respectively. Consequently, it can be inferred that Maillard reaction is significantly affected by pH, which can be used as a control factor whenever the reaction potentially occurs.

O presente estudo foi planejado para investigar a influência de polietileno glicóis sobre a atividade e expressão da P- glicoproteína (P-gp) . Concentrações sub-tóxicas de PGPs e em células Caco-2 foram determinadas por meio do ensaio de MTT. Em seguida, efetuou-se a a medida de captura de Rodamina-123 (Rho-123), um substrato fluorescente de P-gp, em células Caco-2, confrontando com PEG 400 (1% e 2% m/v), PEG 4000 (2% e 4% m/v) e PEG 6000 (2% e 4% m /v), PEG 10000 (2% e 4% w/v), PEG 15000 (1% e 2% m/v), e PEG 35000 (2% e 4% m/v). Essa medida foi efetuada durante a noite, para saber se as concentrações não tóxicas de excipientes são capazes de influenciar a actividade da P-gp. Além disso, realizou-se o western blotting para investigar a expressão da proteína P-gp. Os resultados mostraram que o PEG 400, nas concentrações de 1% (m/v) e 2% (m/v), e PEG 6000, na concentração de 4% (m/v) são capazes de bloquear P-gp. Com base nos resultados conclui-se que os excipientes mencionados poderiam ser utilizados para obstruir o efluxo por P-gp, a fim de aumentar a biodisponibilidade de do fármaco co-administrado.

The present study was planned to investigate the influence of polyethylene glycols (PEGs) on the activity and expression of P-glycoprotein (P-gp). Sub-toxic concentrations of PEGs in Caco-2 cells were determined using the MTT test assay. Then the measurement of Rhodamine-123 (Rho-123) uptake, a P-gp fluorescence substrate, in Caco-2 cells confronting PEG 400 (1% and 2% w/v), PEG 4000 (2% and 4% w/v), PEG 6000 (2% and 4% w/v), PEG 10000 (2% and 4% w/v), PEG 15000 (1% and 2% w/v), and PEG 35000 (2% and 4% w/v) overnight was taken to elucidate whether non-toxic concentrations of PEGs are able to impact P-gp activity. Furthermore, western blotting was carried out to investigate P-gp protein expression. The results showed that PEG 400 at concentrations of 1% (w/v) and 2% (w/v) and PEG 6000 at the concentration of 4% (w/v) are notably capable of blocking P-gp. Based on the obtained results it is concluded that the mentioned excipients could be used to obstruct P-gp efflux transporter in order to increase the bioavailability of co-administered substrate drug.

O objetivo principal do presente estudo foi determinar a permeabilidade de nanopartículas de claritromicina (CLA)-PLGA, utilizando a técnica de perfusão intestinal de passo único em ratos. As nanopartículas de claritromicina foram preparadas por nanoprecipitação, de acordo com a técnica modificada de difusão de solvente quase-emulsão, e suas características físico-químicas avaliadas. Os coeficientes de permeabilidade (Peff) em ratos anestesiados foram determinados em três concentrações diferentes. A solução, ou suspensões, do fármaco em PBS foi perfundida através do segmento de jejuno canulado e as amostras foram tomadas do tubo externo em diferentes tempos até 90 minutos. Os ensaios microbiológico de CLA e de vermelho de fenol das amostras foram realizados, utilizando-se o procedimento de difusão em poço de ágar e de CLAE, respectivamente. O tamanho médio das partículas das nanopartículas preparadas foi de 305 ± 134 nm. O Peff médio da solução de CLA em concentrações de 150, 250 and 400 µg/mL foi de 1.20(±0.32)×10-3, 9.62(±0.46)]×10-4 e de 1.36(±0.95)×10-3 cm/s, respectivamente. O valor correspondente para a mesma concentração de nanopartículas foi de 2.74 (±0.73)×10-3, 2.45(±0.88)×10-3 e de 3.68 (±0.46)×10-3 cm/s, respectivamente. O teste t de Student com duas variáveis mostrou que a permeabilidade intestinal das suspensões de nanopartículas de CLA nas concentrações preparadas foram significativamente aumentadas em comparação com sua solução.

The main objective of the present study was to determine the permeability of clarithromycin (CLA)-PLGA nanoparticles using single-pass intestinal perfusion technique in rats. Clarithromycin nanoparticles were prepared by nano-precipitation according to the modified quasi emulsion solvent diffusion technique and evaluated for their physicochemical characteristics. Permeability coefficients (Peff) in anaesthetized rats were determined at 3 different concentrations. Drug solution or suspensions in PBS was perfused through a cannulated jejunal segment and samples were taken from outlet tubing at different time points up to 90 min. Microbiological assay of CLA and phenol red in the samples were analyzed using an agar well diffusion procedure and HPLC method respectively. The average particle size of prepared nanoparticles was 305 ± 134 nm. The mean Peff of CLA solution in concentrations of 150, 250 and 400 µg/mL was found to be 1.20 (±0.32) ×10-3, 9.62 (±0.46) ×10-4, and 1.36 (±0.95) ×10-3 cm/sec, respectively. The corresponding values for the same concentration of nanoparticles were found to be 2.74 (±0.73) ×10-3, 2.45 (±0.88) ×10-3, and 3.68 (±0.46) ×10-3 cm/s, respectively. The two-tailed Student’s t-test showed that the intestinal permeability of CLA nanoparticle suspensions in prepared concentrations were significantly increased in comparison with its solution.