Poloxamer-based binary hydrogels for delivering tramadol hydrochloride: sol-gel transition studies, dissolution-release kinetics, in vitro toxicity, and pharmacological evaluation.

In this work, poloxamer (PL)-based binary hydrogels, composed of PL 407 and PL 188, were studied with regard to the physicochemical aspects of sol-gel transition and pharmaceutical formulation issues such as dissolution-release profiles. In particular, we evaluated the cytotoxicity, genotoxicity, and in vivo pharmacological performance of PL 407 and PL 407-PL 188 hydrogels containing tramadol (TR) to analyze its potential treatment of acute pain. Drug-micelle interaction studies showed the formation of PL 407-PL 188 binary systems and the drug partitioning into the micelles. Characterization of the sol-gel transition phase showed an increase on enthalpy variation values that were induced by the presence of TR hydrochloride within the PL 407 or PL 407-PL 188 systems. Hydrogel dissolution occurred rapidly, with approximately 30%-45% of the gel dissolved, reaching ~80%-90% up to 24 hours. For in vitro release assays, formulations followed the diffusion Higuchi model and lower K(rel) values were observed for PL 407 (20%, K(rel) = 112.9 ± 10.6 µg · h(-1/2)) and its binary systems PL 407-PL 188 (25%-5% and 25%-10%, K(rel) =80.8 ± 6.1 and 103.4 ± 8.3 µg · h(-1/2), respectively) in relation to TR solution (K(rel) =417.9 ± 47.5 µg · h(-1/2), P<0.001). In addition, the reduced cytotoxicity (V79 fibroblasts and hepatocytes) and genotoxicity (V79 fibroblasts), as well as the prolonged analgesic effects (>72 hours) pointed to PL-based hydrogels as a potential treatment, by subcutaneous injection, for acute pain.

Targeted antitumoral dehydrocrotonin nanoparticles with L-ascorbic acid 6-stearate.

Tumoral cells are known to have a higher ascorbic acid uptake than normal cells. Therefore, the aim of this study was to obtain polymeric nanoparticles containing the antitumoral compound trans-dehydrocrotonin (DHC) functionalized with L-ascorbic acid 6-stearate (AAS) to specifically target this system tumoral cells. Nanoparticle suspensions (NP-AAS-DHC) were prepared by the nanoprecipitation method. The systems were characterized for AAS presence by thin-layer chromatography and for drug loading (81-88%) by UV-Vis spectroscopy. To further characterize these systems, in vitro release kinetics, size distribution (100-140 nm) and Zeta potential by photon-correlation spectroscopic method were used. In vitro toxicity against HL60 cells was evaluated by tetrazolium reduction and Trypan blue exclusion assays. Cell death by apoptosis was quantified and characterized by flow cytometry and caspase activity. Zeta potential analyses showed that the system has a negatively charged outer surface and also indicate that AAS is incorporated on the external surface of the nanoparticles. In vitro release kinetics assay showed that DHC loaded in nanoparticles had sustained release behavior. In vitro toxicity assays showed that NP-AAS-DHC suspension was more effective as an antitumoral than free DHC or NP-DHC and increased apoptosis induction by receptor-mediated pathway.

Níveis comparativos de estresse oxidativo em camundongos em duas situações do limite orgânico: overreaching induzido por treinamento de natação e câncer / Comparative oxidative stress levels in mice submitted to two situations of organic limit: overreaching induced by swimming training and cancer

O objetivo deste trabalho foi comparar concentrações de estresse oxidativo em camundongos da linhagem Balb-C submetidos a duas condições severas de alterações orgânicas: treinamento exaustivo de natação (overreaching - grupo OVER; n = 10) e inoculação por tumor ascítico de Ehrlich (grupo TAE; n = 10). A proposta foi analisar como as duas situações comprometiam o equilíbrio entre os sistemas oxidantes e antioxidantes. Foram investigados alguns marcadores de estresse oxidativo, tais como as substâncias reativas ao ácido tiobarbitúrico (TBARS) e concentrações da atividade da enzima antioxidante catalase (CAT) no hemolisado. Como marcadores de lesão celular, quantificaram-se concentrações plasmáticas das enzimas creatina quinase (CK) e aspartato transferase (AST); complementado; também se observaram padrões de alterações fisiológicas por meio da quantificação plasmática de creatinina e uréia. Como resultados mais importantes, pôde-se observar que, nas duas situações de limite orgânico, seja por exercício exaustivo (OVER) ou pela inoculação de TAE, houve queda abrupta na concentração da enzima CAT (decréscimos de 30 por cento; p < 0,01 e 72 por cento; p < 0,001, respectivamente, comparando-se com o grupo treinado - T). Quanto à concentração de peroxidação lipídica (TBARS), detectaram-se aumentos significativos para os grupos OVER e TAE em relação ao grupo T (52 por cento, p < 0,01; 90 por cento, p < 0,001, respectivamente). Níveis liberados de CK foram mais proeminentes no grupo OVER, enquanto que a quantidade de AST no plasma foi mais elevada no grupo TAE. Chegou-se à conclusão de que os organismos estudados possuem um mesmo perfil de estresse oxidativo em situações limites que envolvem exercício físico e doença. Tais resultados permitirão profissionais envolvidos com elaboração das cargas de treinamento físico a se preocuparem com os períodos recuperativos, o que impede a instalação do quadro de overreaching, o qual se mostrou tão severo...

The aim of this study was to compare oxidative stress levels in mice (Balb-C) submitted to two severe organic conditions: exhaustive swimming training (overreaching - OVER group; n = 10) and inoculation of the Ehrlich's Ascitic Tumor (EAT group; n = 10). Lipid peroxidation, quantified by thiobarbituric acid reactive substances (TBARS), and levels of antioxidant enzyme (catalase- CAT) were used as indicators of oxidative stress. Muscle damage levels were measured through plasma creatine kinase (CK), aspartate transaminase (AST) as well as blood creatinine and urea activities samples. As main results, it has been observed that in both situations, whether by exhaustive exercise (OVER) or inoculation of EAT, dramatic decrease in the catalase activity levels was present when compared with the training group (T) (30 percent; p < 0.01 and 72 percent; p < 0.001, respectively) with concomitant increase in plasma TBARS concentration (52 percent; p < 0.01 and 90 percent p < 0.001, respectively). Plasma CK levels were more prominent in the OVER group, while the amount of AST plasma was higher in the EAT group. We concluded that the same profile of oxidative stress was found in situations involving exhaustive exercise and pathology. These results will allow professionals involved with load training manipulation to be concerned with the rest periods, preventing hence the installation of overreaching, which in terms of oxidative stress, was as severe as a pathological conditions.

Effect of angiotensin II and losartan on the phagocytic activity of peritoneal macrophages from Balb/C mice

Angiotensin II (AII), a product of rennin-angiotensin system, exerts an important role on the function of immune system cells. In this study, the effect of AII on the phagocytic activity of mouse peritoneal macrophages was assessed. Mice peritoneal macrophages were cultured for 48 h and the influence of different concentrations of AII (10-14 to 10-7 M) and/or losartan, 10-16 to 10-6 M), an AT1 angiotensin receptor antagonist, on phagocytic activity and superoxide anion production was determined. Dimethylthiazoldiphenyltetrazolium bromide reduction and the nucleic acid content were used to assess the cytotoxicity of losartan. A stimulatory effect on phagocytic activity (P < 0.05) was observed with 10-13 M and 10-12 M AII concentrations. The addition of losartan (up to10-14 M) to the cell cultures blocked (P < 0.001) the phagocytosis indicating the involvement of AT1 receptors. In contrast, superoxide anion production was not affected by AII or losartan. The existence of AT1 and AT2 receptors in peritoneal macrophages was demonstrated by immunofluorescence microscopy. These results support the hypothesis that AII receptors can modulate murine macrophage activity and phagocytosis, and suggest that AII may have a therapeutic role as an immunomodulatory agent in modifying the host resistance to infection.