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Targeted delivery aims to enhance cellular uptake and improve therapeutic outcome with higher disease specificity. The expression of transferrin receptor (TfR) is upregulated on tumor cells, which make the protein Tf and its receptor vastly relevant when applied to targeting strategies. Here, we proposed Tf-decorated pH-sensitive PLGA nanoparticles containing the chemosensitizer poloxamer as a carrier for doxorubicin delivery to tumor cells (Tf-DOX-PLGA-NPs), aiming at alleviating multidrug resistance (MDR). We performed a range of in vitro studies to assess whether targeted NPs have the ability to improve DOX antitumor potential on resistant NCI/ADR-RES cells. All evaluations of the Tf-decorated NPs were performed comparatively to the nontargeted counterparts, aiming to evidence the real role of NP surface functionalization, along with the benefits of pH-sensitivity and poloxamer, in the improvement of antiproliferative activity and reversal of MDR. Tf-DOX-PLGA-NPs induced higher number of apoptotic events and ROS generation, along with cell cycle arrest. Moreover, they were efficiently internalized by NCI/ADR-RES cells, increasing DOX intracellular accumulation, which supports the greater cell killing ability of these targeted NPs with respect to MDR cells. Altogether, these findings supported the effectiveness of the Tf-surface modification of DOX-PLGA-NPs for an improved antiproliferative activity. Therefore, our pH-responsive Tf-inspired NPs are a promising smart drug delivery system to overcome MDR effect at some extent, enhancing the efficacy of DOX antitumor therapy.

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Lipid-core nanocapsules (LNC) were designed and prepared as a colloidal system for drug targeting to improve the stability of drugs and allow their controlled release. For parenteral administration, it is necessary to ensure formulation sterility. However, sterilization of nanotechnological devices using an appropriate technique that keeps the supramolecular structure intact remains a challenge. This work aimed to evaluate the effect of autoclaving on the physicochemical characteristics of LNC. Formulations were prepared by the self-assembling method, followed by isotonization and sterilization at varying times and temperatures. The isotonicity was confirmed by determining the freezing temperature, which was -0.51°C. The formulation was broadly characterized, and the diameter of the particles was determined utilizing complementary methods. To evaluate the chemical stability of poly(ε-caprolactone), its molecular weight was determined by size exclusion chromatography. The physicochemical characteristics (average diameter, viscosity, and physical stability) of the formulation were similar before and after adding glycerol and conducting the sterilization at the highest temperature (134°C) and the shorter exposure time (10 min). After autoclaving, the sterility test was performed and showed no detectable microbial growth. Multiple light scattering demonstrated that the formulations were kinetically stable, and the mean diameter was constant for 6 months, corroborating this result. The polymer was chemically stable in the sterilized formulation. Isotonic and sterile LNC aqueous suspensions were produced using glycerol and autoclaving. Briefly, the results open an opportunity to produce an isotonic and sterile LNC aqueous dispersion applicable as nanomedicine for intravenous administration in clinical trials.

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A lot of effort has been devoted to achieving active targeting for cancer therapy in order to reach the right cells. Hence, increasingly it is being realized that active-targeted nanocarriers notably reduce off-target effects, mainly because of targeted localization in tumors and active cellular uptake. In this context, by taking advantage of the overexpression of transferrin receptors on the surface of tumor cells, transferrin-conjugated nanodevices have been designed, in hope that the biomarker grafting would help to maximize the therapeutic benefit and to minimize the side effects. Notably, active targeting nanoparticles have shown improved therapeutic performances in different tumor models as compared to their passive targeting counterparts. In this review, current development of nano-based devices conjugated with transferrin for active tumor-targeting drug delivery are highlighted and discussed. The main objective of this review is to provide a summary of the vast types of nanomaterials that have been used to deliver different chemotherapeutics into tumor cells, and to ultimately evaluate the progression on the strategies for cancer therapy in view of the future research.

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The encapsulation of antitumor drugs in nanosized systems with pH-sensitive behavior is a promising approach that may enhance the success of chemotherapy in many cancers. The nanocarrier dependence on pH might trigger an efficient delivery of the encapsulated drug both in the acidic extracellular environment of tumors and, especially, in the intracellular compartments through disruption of endosomal membrane. In this context, here we reported the preparation of chitosan-based nanoparticles encapsulating methotrexate as a model drug (MTX-CS-NPs), which comprises the incorporation of an amino acid-based amphiphile with pH-responsive properties (77KS) on the ionotropic complexation process. The presence of 77KS clearly gives a pH-sensitive behavior to NPs, which allowed accelerated release of MTX with decreasing pH as well as pH-dependent membrane-lytic activity. This latter performance demonstrates the potential of these NPs to facilitate cytosolic delivery of endocytosed materials. Outstandingly, the cytotoxicity of MTX-loaded CS-NPs was higher than free drug to MCF-7 tumor cells and, to a lesser extent, to HeLa cells. Based on the overall results, MTX-CS-NPs modified with the pH-sensitive surfactant 77KS could be potentially useful as a carrier system for intracellular drug delivery and, thus, a promising targeting anticancer chemotherapeutic agent.

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The growing demand for efficient chemotherapy in many cancers requires novel approaches in target-delivery technologies. Nanomaterials with pH-responsive behavior appear to have potential ability to selectively release the encapsulated molecules by sensing the acidic tumor microenvironment or the low pH found in endosomes. Likewise, polyethylene glycol (PEG)- and poloxamer-modified nanocarriers have been gaining attention regarding their potential to improve the effectiveness of cancer therapy. In this context, DOX-loaded pH-responsive nanoparticles (NPs) modified with PEG or poloxamer were prepared and the effects of these modifiers were evaluated on the overall characteristics of these nanostructures. Chitosan and tripolyphosphate were selected to form NPs by the interaction of oppositely charged compounds. A pH-sensitive lysine-based amphiphile (77KS) was used as a bioactive adjuvant. The strong dependence of 77KS ionization with pH makes this compound an interesting candidate to be used for the design of pH-sensitive devices. The physicochemical characterization of all NPs has been performed, and it was shown that the presence of 77KS clearly promotes a pH-triggered DOX release. Accelerated and continuous release patterns of DOX from CS-NPs under acidic conditions were observed regardless of the presence of PEG or poloxamer. Moreover, photodegradation studies have indicated that the lyophilization of NPs improved DOX stability under UVA radiation. Finally, cytotoxicity experiments have shown the ability of DOX-loaded CS-NPs to kill HeLa tumor cells. Hence, the overall results suggest that these pH-responsive CS-NPs are highly potent delivery systems to target tumor and intracellular environments, rendering them promising DOX carrier systems for cancer therapy.

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Engineered nanomaterials are emerging functional materials with technologically interesting properties and a wide range of promising applications, such as drug delivery devices, medical imaging and diagnostics, and various other industrial products. However, concerns have been expressed about the risks of such materials and whether they can cause adverse effects. Studies of the potential hazards of nanomaterials have been widely performed using cell models and a range of in vitro approaches. In the present review, we provide a comprehensive and critical literature overview on current in vitro toxicity test methods that have been applied to determine the mechanisms underlying the cytotoxic effects induced by the nanostructures. The small size, surface charge, hydrophobicity and high adsorption capacity of nanomaterial allow for specific interactions within cell membrane and subcellular organelles, which in turn could lead to cytotoxicity through a range of different mechanisms. Finally, aggregating the given information on the relationships of nanomaterial cytotoxic responses with an understanding of its structure and physicochemical properties may promote the design of biologically safe nanostructures.

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Risedronate, an anti-osteoporotic drug, is associated with low patient compliance due to the upper gastrointestinal side-effects and stringent dosing regimes. This study aimed to prepare and characterize risedronate-loaded Eudragit® S100 microparticles and develop a final dosage form by the compression of microparticles using direct tableting excipients. Microparticles were prepared by spray-drying and presented yield of 54%, encapsulation efficiency higher than 90%, mean diameter of 3.3 µm, moisture content around 8% and exhibited spherical shape and poor flowability. At pH 1.2, 23% of risedronate was released from microparticles in 120 min, while at pH 6.8 the drug took 90 min to reach 99.5%. Microparticles were compressed into tablets using microcrystalline cellulose, magnesium stearate, colloidal silicon dioxide and 2 polyvinylpyrrolidone concentrations (5% and 15%). Tablets presented low variations in weight, thickness and drug content. Besides, the formulations showed sufficient hardness, low friability and disintegrated in less than 15 min. In acid medium, no more than 16% of the drug was released in 120 min, while in intestinal medium the formulations prolonged the risedronate release for 240 min. Finally, the developed tableted microparticles can be considered a promising dosage form for oral risedronate administration.

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A stability-indicating MEKC method was developed and validated for the simultaneous determination of aliskiren (ALI) and hydrochlorothiazide (HCTZ) in pharmaceutical formulations using ranitidine as an internal standard (IS). Optimal conditions for the separation of ALI, HCTZ and its major impurity chlorothiazide (CTZ), IS and degradation products were investigated. The method employed 47 mM Tris buffer and 47 mM anionic detergent SDS solution at pH 10.2 as the background electrolyte. MEKC method was performed on a fused-silica capillary (40 cm) at 28°C. Applied voltage was 26 kV (positive polarity) and photodiode array (PDA) detector was set at 217 nm. The method was validated in accordance with the ICH requirements. The method was linear over the concentration range of 5-100 and 60-1200 µg/mL for HCTZ and ALI, respectively (r(2) >0.9997). The stability-indicating capability of the method was established by enforced degradation studies combined with peak purity assessment using the PDA detection. Precision and accuracy evaluated by RSD were lower than 2%. The method proved to be robust by a fractional factorial design evaluation. The proposed MEKC method was successfully applied for the quantitative analysis of ALI and HCTZ both individually and in a combined dosage tablet formulation to support the quality control.

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A simple RP-HPLC method was developed and validated for the determination of rimonabant in a pharmaceutical dosage form. The separation was performed on a C18 column (150 x 4.6 mm id, 5 microm) with acetonitrile-water (75 + 25, v/v) mobile phase. The detection was achieved with a diode array detector at 215 nm. The method was linear in the concentration range of 0.5-50 microg/mL (r = 1) with an LOQ of 0.24 microg/mL. The specificity and stability-indicating capability of the method were proved through forced degradation studies, and it was shown that there was no increase of the cytotoxicity. Rimonabant was exposed to hydrolytic, oxidative, and photolytic stress conditions, and the samples were analyzed by the proposed method. Under optimized conditions, rimonabant was successfully separated from its degradation products within 10 min, and the resolution was found to be greater than 2. The RSD values for intraday and interday precision were always less than 2%. Interday accuracy ranged from 98.1 to 101.7% (RSD = 1.0%). Moreover, method validation demonstrated acceptable results for sensitivity and robustness. The method was applied for the quantitative analysis of rimonabant in a tablet dosage form to demonstrate its use for improving the QC of pharmaceuticals containing this drug.

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Ceftiofur sodium is a third-generation broad-spectrum cephalosporin antibiotic, formulated as an intramuscular injection, that is approved for use in pigs, cattle, poultry, and dogs. The present work reports a method to quantify ceftiofur in powder for injection by comparing the cylinder plate assay and the liquid chromatographic (LC) method. The assay is based on the inhibitory effect of ceftiofur upon the strain of Micrococcus luteus ATCC 10240 used as the test microorganism. Ceftiofur sodium at concentrations ranging from 2.0 to 8.0 microg/mL can be measured in powder for injection. A prospective validation showed that the method is linear (r2 = 0.9998), with precise relative standard deviation (RSD) of 0.8% for product A (Excenel; Pharmacia and Upjohn Co., Kalamazoo, MI) and of 0.6% for product B (Topcef; Eurofarma Lab. Ltda, São Paulo, Brazil), with intermediate precision; between-day RSD = 1.0 and 1.1%, between-analyst RSD = 0.8 and 0.8% for products A and B, respectively and accurately. The comparison between bioassay and LC by analysis of variance and Student's t-test showed no significant difference among methodologies. The results demonstrated the validity of the proposed bioassay that is simple and a useful alternative methodology for analysis of ceftiofur in routine quality control.

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