Eliana Martins Lima

Development of topotecan loaded lipid nanoparticles for chemical stabilization and prolonged release

Topotecan is an important cytotoxic drug that has gained broad acceptance in clinical use for the treatment of refractory ovarian and small-cell lung cancer. The lactone active form of topotecan can be hydrolyzed in vivo, decreasing the drugs therapeutic efficacy. Lipid encapsulation may promote in vivo stabilization by removing topotecan from aqueous media. Earlier reports of topotecan lipid nanoencapsulation have focused on liposomal encapsulation; however, the higher stability and cost-effectiveness of solid lipid nanoparticles (SLN) highlight the potential of these nanoparticles as an advantageous carrier for topotecan. The initial motivation for this work was to develop, for the first time, solid lipid nanoparticles and nanostructured lipid carriers (NLC) with a high drug loading for topotecan. A microemulsion technique was employed to prepare SLNs and NLCs and produced homogeneous, small size, negatively charged lipid nanoparticles with high entrapment efficiency and satisfactory drug loading. However, low recovery of topotecan was observed when the microemulsion temperature was high and in order to obtain high quality nanoparticles, and precise control of the microemulsion temperature is critical. Nanoencapsulation sustained topotecan release and improved its chemical stability and cytotoxicity. Surprisingly, there were no significant differences between the NLCs and SLNs, and both are potential carriers for topotecan delivery.

Impact of lipid dynamic behavior on physical stability, in vitro release and skin permeation of genistein-loaded lipid nanoparticles

The aim of this study was to develop lipid nanoparticles to deliver genistein (GEN) to deeper skin layers. To do so, the impact of lipid dynamic behavior (nanoparticle flexibility) on stability, release and skin permeation studies was verified. GEN-loaded solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) were obtained and characterization was undertaken. Freshly prepared nanoparticles were produced with similar features (i.e., drug loading). However, a higher level of crystallization in GEN-SLN formulation was observed in differential scanning calorimetry experiments. Electron paramagnetic resonance measurements showed a lower mobility of the spin labels in the SLN, which would indicate that NLC could be more flexible than SLN. Despite the fact that NLC demonstrated more fluidity, GEN was released more slowly from NLC than from SLN. Skin permeation studies demonstrated that lipid nanoparticles increased GEN skin retention. More flexible particles (NLC) also favored drug penetration into deeper skin layers. GEN-NLC would seem to be a promising formulation for GEN topical delivery.

Stability and in vitro release profile of enalapril maleate from different commercially available tablets: Possible therapeutic implications

Stability of enalapril maleate formulations can be affected when the product is exposed to higher temperature and humidity, with the formation of two main degradation products: enalaprilat and a diketopiperazine derivative. In this work, stability and drug release profiles of 20 mg enalapril maleate tablets (reference, generic and similar products) were evaluated. After 180 days of the accelerated stability testing, most products did not exhibit the specified amount of drug. Additionally, drug release profiles were markedly different from that of the reference product, mainly due to drug degradation. Changes in drug concentration and drug release profile of enalapril formulations are strong indicators of a compromised bioavailability, with possible interferences on the therapeutic response for this drug.

In vitro basal cytotoxicity assay applied to estimate acute oral systemic toxicity of grandisin and its major metabolite

Preclinical investigations can start with preliminary in vitro studies before using animal models. Following this approach, the number of animals used in preclinical acute toxicity testing can be reduced. In this study, we employed an in-house validated in vitro cytotoxicity test based on the Spielmann approach for toxicity evaluation of the lignan grandisin, a candidate anticancer agent, and its major metabolite, the 4-O-demethylgrandisin, by neutral red uptake (NRU) assay, on mouse fibroblasts Balb/c 3T3 cell line. Using different concentrations of grandisin and its major metabolite (2.31; 1.16; 0.58; 0.29; 0.14; 0.07; 0.04; 0.002 μM) in Balb/c 3T3-A31 NRU cytotoxicity assay, after incubation for 48 h, we obtained IC(50) values for grandisin and its metabolite of 0.078 and 0.043 μM, respectively. The computed LD(50) of grandisin and 4-O-demethylgrandisin were 617.72 and 429.95 mg/kg, respectively. Both were classified under the Globally Harmonized System as category 4. Since pharmacological and toxicological data are crucial in the developmental stages of drug discovery, using an in vitro assay we demonstrated that grandisin and its metabolite exhibit distinct toxicity profiles. Furthermore, results presented in this work can contribute to reduce the number of animals required in subsequent pharmacological/toxicological studies.

Biodegradable nanoparticles designed for drug delivery: The number of nanoparticles impacts on cytotoxicity.

Nanostructured drug delivery systems are based on biocompatible and biodegradable components. Composition, size and membrane surface properties are characteristics that may influence cell viability in cytotoxicity assays. In this work, four nanostructured systems commonly used for drug delivery were prepared and cytotoxicity was evaluated on human lymphocytes and Balb/c 3T3 fibroblasts. The hemolytic potential was also investigated. Polymeric nanocapsules (NC) and nanospheres (NS), nanostructured lipid carriers (NLC) and liposomes were prepared and characterized for size, distribution, zeta potential and number per volume of the colloidal dispersion. Cell viability was evaluated, 24 and 48h, by MTT and neutral red assays (NR). Cells were incubated with each particle in eight different dilutions varying from 2.1×10(4) to 2.1×10(11)particles/mL. Diameter of nanoparticles was between 130 and 200nm, all samples exhibited narrow size distribution (polydispersity index below 0.1) and zeta potential varied from -6.8 to -19.5mV. NC, NS and NLC reduced cell viability in a dilution dependent manner. For these nanoparticles, the higher number of particles induced cell death for both cell types. Liposomes did not cause loss of cell viability even at the highest number of particles. Results suggest that, depending on the kind of nanoparticle, the number of particles in the dispersion can negatively influence cell viability in pre-clinical drug development.

Design and characterization of sustained release ketoprofen entrapped carnauba wax microparticles

Context: Ketoprofen is a non-steroid anti-inflammatory drug (NSAID) used in the treatment of rheumatic diseases and in mild to moderate pain. Ketoprofen has a short biological half-life and the commercially available conventional release formulations require dosages to be administered at least 2–3 times a day. Due to these characteristics, ketoprofen is a good candidate for the preparation of controlled release formulations. Objectives: In this work, a multiparticulate-sustained release dosage form containing ketoprofen in a carnauba wax matrix was developed. Methods: Particles were prepared by an emulsion congealing technique. System variables were optimized using fractional factorial and response surface experimental design. Characterization of the particles included size and morphology, flow rate, drug loading and in vitro drug release. Results: Spherical particles were obtained with high drug load and sustained drug release profile. The optimized particles had an average diameter of approximately 200 µm, 50% (w/w) drug load, good flow properties and prolonged ketoprofen release for more than 24 h. Conclusions: Carnauba wax microspheres prepared in this work represent a new multiparticulate-sustained release system for the NSAID ketoprofen, exhibiting good potential for application in further pharmaceutical processes.

In vitro skin penetration of clobetasol from lipid nanoparticles: drug extraction and quantitation in different skin layers

Clobetasol propionate (CP) is a potent topical corticosteroid that causes several cutaneous and systemic side effects. In the present work, CP was encapsulated in nanostructured lipid carriers (NLCs) to increase drug retention in the outer skin layers and improve the safety of topical therapy. NLCs were prepared using a microemulsion technique with a mixture of lecithin, taurodeoxycholate, stearic acid, and oleic acid. In vitro penetration studies were performed in a modified Franz-type diffusion cell, and porcine ears were used as a model of human skin. A simple and sensitive liquid chromatographic method was developed and validated for clobetasol determination in different skin layers. NLCs presented uniform size distribution, high zeta potentialand entrapment efficiency values (> 98%). The analytical procedure was validated according to FDA guidelines. Clobetasol recoveries from skin samples were higher than 85%, with no interference of skin components and NLC ingredients. In experiments, after 6 h, a higher drug accumulation in the stratum corneum arising from NLCs compared to aqueous CP solution was observed. Thus, the NLCs demonstrated high potential for targeting CP to the skin and ensuring drug accumulation in the stratum corneum.

Curcuminoids from Curcuma longaL. reduced intestinal mucositis induced by 5-fluorouracil in mice: Bioadhesive, proliferative, anti-inflammatory and antioxidant effects

Introduction Intestinal mucositis is a frequent limiting factor in anticancer therapy and there is currently no broadly effective treatment targeted to cure this side effect. Objective This study aimed to evaluate the effects of a mucoadhesive formulation containing curcuminoids (MFC) from Curcuma longa L. on the pathogenesis of 5-fluorouracil (5-FU)-induced intestinal mucositis. Methods Three intraperitoneal 5-FU injections (200 mg/kg) were used to induce intestinal mucositis in adult Swiss male mice. Treatment was provided orally (MFC 3.75, 7.5 and 15 mg/kg), thirty minutes before 5-FU injections, daily until euthanasia. Duodenal samples were collected to perform morphometric and histopathological analysis, to investigate the expression of Ki-67, p53, Bax and Bcl-2 by immunohistochemistry, to evaluate neutrophil activity myeloperoxidase (MPO)-mediated and oxidative stress by malondialdehyde (MDA) determination. Mice body weight was assessed as well. Results As expected, 5-FU induced a significant weight loss (∼17%, P < 0.001), shortening in villi height (∼55.4%) and crypts depth (∼47%), and increased (∼64%) the histological severity score when compared to other groups (P < 0.05). These pathological changes were markedly alleviated by the three MFC treatment doses (P < 0.05), in special with the dose MFC 15 mg/kg. This dose also stimulated cell proliferation by ∼90% in the epithelial cells lining from villi and crypts (P < 0.05), reduced MPO levels and MDA formation by 60% and 44%, respectively (P < 0.05). Conclusions Our data suggest the therapeutic potential of the formulation for treating intestinal mucositis in mice. Supplementary studies are underway searching for the elucidation of mechanisms involved in the protective effects of MFC in order to make this formulation a clinical tool for mucositis treatment.

Clobetasol‐loaded nanostructured lipid carriers for epidermal targeting

The aim of this study was to investigate in vitro the epidermal targeting potential of clobetasol propionate‐loaded nanostructured lipid carriers (CP‐NLC) when compared to that of chitosan‐coated (CP‐NLC‐C).

Cytotoxicity and antiangiogenic activity of grandisin.

Objectives The antitumoural properties of grandisin, a tetrahydrofuran neolignan from Piper solmsianum, were investigated by in‐vitro and in‐vivo assays using the Ehrlich ascites tumoural (EAT) model.