Improved pharmacokinetics and reduced side effects of doxorubicin therapy by liposomal co-encapsulation with curcumin

The goal of the current study was to investigate the pharmacokinetic profile, tissue distribution and adverse effects of long-circulating liposomes (LCL) with curcumin (CURC) and doxorubicin (DOX), in order to provide further evidence for previously demonstrated enhanced antitumor efficacy in colon cancer models. The pharmacokinetic studies were carried out in healthy rats, following the i.v. injection of a single dose of LCL-CURC-DOX (1 mg/kg DOX). For the tissue distribution study, DOX concentration in tumours, heart and liver were measured after the administration of two i.v. doses of LCL-CURC-DOX (2.5 mg/kg DOX and 5 mg/kg CURC) to Balb/c mice bearing C26 colon tumours. Markers of murine cardiac and hepatic oxidative status were determined to provide additional insights into the benefit of co-encapsulating CURC and DOX in LCL over DOX-induced adverse effects in these organs. The current study demonstrated that the liposomal association of CURC and DOX effectively improved the pharmacokinetics and biodistribution of DOX, limiting its side effects, via CURC-dependent antioxidant effects.

A quality by design approach for the development of lyophilized liposomes with simvastatin

Lyophilization is used to ensure an increased shelf-life of liposomes, by preserving them in dry state, more stable than the aqueous dispersions. When stored as aqueous systems, the encapsulated drugs are released and the liposomes might aggregate or fuse. The aim of this study was to develop and optimize a lyophilized formulation of simvastatin (SIM) loaded into long circulating liposomes using the Quality by Design (QbD) approach. Pharmaceutical development by QbD aims to identify characteristics that are critical for the final product quality, and to establish how the critical process parameters can be varied to consistently produce a product with the desired characteristics. In the case of lyophilized liposomes, the choice of the optimum formulation and technological parameters has to be done, in order to protect the integrity of the liposomal membrane during lyophilization. Thus, the influence of several risk factors (3 formulation factors: PEG proportion, cholesterol concentration, the cryoprotectant to phospholipids molar ratio, and 2 process parameters: the number of extrusions through 100 nm polycarbonate membranes and the freezing conditions prior lyophilization) over the critical quality attributes (CQAs) of lyophilized long circulating liposomes with simvastatin (lyo-LCL-SIM), i.e. the size, the encapsulated SIM concentration, the encapsulated SIM retention, the Tm change and the residual moisture content, was investigated within the current study using the design of experiments tool of QbD. Moreover, the design space for lyo-LCL-SIM was determined, in which the established quality requirements of the product are met, provided that the risk factors vary within the established limits.

Liposomal prednisolone phosphate potentiates the antitumor activity of liposomal 5-fluorouracil in C26 murine colon carcinoma in vivo

The antitumor efficacy of 5-fluorouracil (5-FU) in advanced colorectal cancer (CRC) is hindered not only by the low therapeutic index, but also by tumor cell resistance to this cytotoxic drug. Therefore, to enhance the 5-FU antitumor activity, the present research used a novel tumor-targeted therapy based on the co-administration of 5-FU encapsulated in long-circulating liposomes (LCL-5-FU) together with liposomal prednisolone phosphate (LCL-PLP), a formulation with known anti-angiogenic actions on C26 murine colon carcinoma cells. Thus, we assessed the in vivo effects of the combined liposomal drug therapy on C26 carcinoma growth as well as on the production of molecular markers with key roles in tumor development such as angiogenic, inflammatory, and oxidative stress molecules. To get further insight into the polarization state of tumor microenvironment after the treatment, we determined the IL-10/IL-12p70 ratio in tumors. Our results showed that combined liposomal drug therapy inhibited almost totally tumor growth and was superior as antitumor activity to both single liposomal drug therapies tested. The antitumor efficacy of the combined therapy was mainly related to the anti-angiogenic and anti-inflammatory actions on C26 carcinoma milieu, being favored by its controlling effect on intratumor oxidative stress and the skewing of polarization of tumor microenvironmental cells toward their antineoplastic phenotypes. Thus, our study unveils a promising treatment strategy for CRC that should be furthermore considered.

Development of antiproliferative long-circulating liposomes co-encapsulating doxorubicin and curcumin, through the use of a quality-by-design approach

The aim of this work was to use the quality-by-design (QbD) approach in the development of long-circulating liposomes co-loaded with curcumin (CUR) and doxorubicin (DOX) and to evaluate the cytotoxic potential of these liposomes in vitro using C26 murine colon carcinoma cell line. Based on a risk assessment, six parameters, namely the phospholipid, CUR and DOX concentrations, the phospholipid:cholesterol molar ratio, the temperature during the evaporation and hydration steps and the pH of the phosphate buffer, were identified as potential risk factors for the quality of the final product. The influence of these variables on the critical quality attributes of the co-loaded liposomal CUR and DOX was investigated: particle size, zeta potential, drug loading and entrapment efficiency. For this, a 2⁶⁻² factorial design was employed to establish a proper regression model and to generate the contour plots for the responses. The obtained data served to establish the design space for which different combinations of variables yielded liposomes with characteristics within predefined specifications. The validation of the model was carried out by preparing two liposomal formulations corresponding to the robust set point from within the design space and one outside the design space and calculating the percentage bias between the predicted and actual experimental results. The in vitro antiproliferative test showed that at higher CUR concentrations, the liposomes co-encapsulating CUR and DOX had a greater cytotoxic effect than DOX-loaded liposomes. Overall, this study showed that QbD is a useful instrument for controlling and optimizing the manufacturing process of liposomes co-loaded with CUR and DOX and that this nanoparticulate system possesses a great potential for use in colon cancer therapy.

Pathophysiology of cyanoginosin-LR: in vivo and in vitro studies

Cyanoginosin-LR, one of the group of virulent cyclic heptapeptide toxins (cyanoginosins) isolated from some strains of the cyanobacterium, Microcystis aeruginosa, kills mice within 1-2 hr after iv or ip injection. Although the liver is a target organ of the toxin, the rapidity of lethality is incompatible with metabolic death from failure of hepatocellular function. However, disintegration of sinusoidal endothelium causes massive intrahepatic hemorrhage. The loss of the structural integrity of hepatic sinusoids provides a previously undescribed mechanism for embolization of disintegrating cells from the liver to the lung. No injury to either cultured bovine pulmonary artery endothelial cells or mouse peritoneal macrophages was observed following prolonged incubation with high concentrations of the toxin, and there was no increase in vascular permeability to 125I-labeled albumin detected before intrahepatic hemorrhage. However, plasma fibronectin increased transiently after toxin injection. Acute, severe thrombocytopenia, a characteristic of cyanoginosin-LR toxicity, remains unexplained since platelets did not concentrate in the lungs, liver, or spleen. There are similarities between the effects of cyanoginosin-LR and of the lipopolysaccharide endotoxins, such as elevations of plasma levels of thromboxane B2 and 6-keto-prostaglandin F1 alpha.