Receptor-targeted nanoparticles modulate cannabinoid anticancer activity through delayed cell internalization.

Δ9-tetrahydrocannabinol (Δ9-THC) is known for its antitumor activity and palliative effects. However, its unfavorable physicochemical and biopharmaceutical properties, including low bioavailability, psychotropic side effects and resistance mechanisms associated to dosing make mandatory the development of successful drug delivery systems. In this work, transferring (Tf) surface-modified Δ9-THC-loaded poly(lactide-co-glycolic) nanoparticles (Tf-THC-PLGA NPs) were proposed and evaluated as novel THC-based anticancer therapy. Furthermore, in order to assess the interaction of both the nanocarrier and the loaded drug with cancer cells, a double-fluorescent strategy was applied, including the chemical conjugation of a dye to the nanoparticle polymer along with the encapsulation of either a lipophilic or a hydrophilic dye. Tf-THC PLGA NPs exerted a cell viability decreased down to 17% vs. 88% of plain nanoparticles, while their internalization was significantly slower than plain nanoparticles. Uptake studies in the presence of inhibitors indicated that the nanoparticles were internalized through cholesterol-associated and clathrin-mediated mechanisms. Overall, Tf-modification of PLGA NPs showed to be a highly promising approach for Δ9-THC-based antitumor therapies, potentially maximizing the amount of drug released in a sustained manner at the surface of cells bearing cannabinoid receptors.

Engineering of Δ9-tetrahydrocannabinol delivery systems based on surface modified-PLGA nanoplatforms.

The objective of this work is to develop a nanoplatform that can potentiate the oral administration of Δ9-tetrahidrocannabinol, a highly lipophilic active agent with very promising antiproliferative and antiemetic activities. To that aim, colloidal carriers based on the biodegradable and biocompatible poly(D,L-lactide-co-glycolide) were investigated. Such delivery systems were prepared by nanoprecipitation, and nanoparticle engineering further involved surface modification with a poly(ethylene glycol), chitosan, or poly(ethylene glycol)-chitosan shells to assure the greatest uptake by intestinal cells and to minimize protein adsorption. Characterization of the nanoplatforms included particle geometry (size and shape), electrophoretic properties (surface charge). Δ9-tetrahydrocannabinol vehiculization capabilities (loading and release), blood compatibility, and cellular uptake and cytotoxicity. Results were satisfactorily used to define the optimum engineering conditions to formulate surface modified nanoparticles for the efficient oral administration of Δ9-tetrahydrocannabinol. To the best of our knowledge, this is the first time that biocompatible polymeric nanoparticles have been formulated for Δ9-tetrahydrocannabinoldelivery.

Enhanced cellular uptake and biodistribution of a synthetic cannabinoid loaded in surface-modified poly(lactic-co-glycolic acid) nanoparticles.

This article aimed to produce, characterize and evaluate different surface-modified naphthalen-1-yl-(4-pentyloxynaphthalen-1-yl)methanone (CB13) loaded poly(lactic-co-glycolic acid) nanoparticles in order to improve their oral absorption and in vivo biodistribution. Plain and surface-modified PLGA nanoparticles were successfully prepared using a nanoprecipitation method. Chitosan, Eudragit RS, lecithin and vitamin E were used as surface modifying agents. The NPs were evaluated in terms of mean diameter and size distribution, zeta potential, morphology, drug loading, drug release profiles, mucoadhesive properties, in vitro cell viability and uptake and in vivo biodistribution. Mean particle size distributions in the range of 253-344 nm, spherical shape and controlled zeta potential values were observed depending on the additive employed. High values of entrapment efficiency were obtained for all the formulations. Lecithin and vitamin E modified particles showed higher release rates when compared to the rest of formulations. A clear improvement in ex vivo mucoadhesion properties was observed in the case of chitosan- and Eudragit RS-modified nanoparticles. Chitosan-poly(lactic-co-glycolic acid) nanoparticles showed the highest uptake values on Caco-2 cells. Biodistribution assays proved that most of the particles were accumulated in liver and spleen. An important goal has been achieved in this investigation: CB13, a highly lipophilic drug with low water solubility, can reach the interior of cells more efficiently when it is included in these surface-modified polymeric carriers.

Cannabinoid derivate-loaded PLGA nanocarriers for oral administration: formulation, characterization, and cytotoxicity studies.

CB13 (1-Naphthalenyl[4-(pentyloxy)-1-naphthalenyl]methanone)-loaded poly(lactic-co-glycolic acid) nanoparticles (NPs) were produced by nanoprecipitation and tested for their in vitro release behavior and in vitro cytotoxicity assays. The effects of several formulation parameters such as polymer type, surfactant concentration, and initial drug amount were studied. NPs had a particle size 90-300 nm in diameter. Results obtained show that the main influence on particle size was the type of polymer employed during the particle production: the greater the hydrophobicity, the smaller the particle size. In terms of encapsulation efficiency (%), high values were achieved (∼68%-90%) for all formulations prepared due to the poor solubility of CB13 in the external aqueous phase. Moreover, an inverse relationship between release rate and NP size was found. On the other hand, low molecular weight and low lactide content resulted in a less hydrophobic polymer with increased rates of water absorption, hydrolysis, and erosion. NPs showed no cytotoxicity and may be considered to be appropriate for drug-delivery purposes.

Use of Flow Focusing® technology to produce tobramycin-loaded PLGA microparticles for pulmonary drug delivery.

In the present work, a promising formulation of an inhaled powder based on tobramycin-loaded microparticles has been reported. Biodegradable microparticles with controlled diameters in the range of 1-5 µm and narrow size distribution were synthesized by Flow Focusing® technology. Particles production was planned and optimized with the aid of a well-established mathematic model. Close agreements between theoretical an experimental sizes were obtained. To deliver a high payload of tobramycin to the lungs, the influence of surfactant concentration, polymer-drug ratio and initial drug concentration were investigated. For chosen formulations, drug delivery profiles were also studied. In some cases, it was found a controlled drug delivery for more than ten days, which could represent an important advance in the treatment of chronic lung infections. Other particles factors affecting deposit of an aerosol in the lung were also studied, such as surface charge and density.

Role of the electrokinetic properties on the stability of mebendazole suspensions for veterinary applications.

This work is focused on the analysis of the effect of basic physicochemical aspects (surface thermodynamic and electrokinetic characteristics) on the stability and redispersibility properties of mebendazole aqueous suspensions. To our knowledge, previous investigations on the formulation of mebendazole suspensions have been not devoted to the elucidation of the colloidal behavior of this benzimidazole carbamate. A deep thermodynamic and electrokinetic characterization, considering the effect of both pH and ionic strength, was carried out with that purpose. It was found that the hydrophobicity and, the surface charge and electrical double layer thickness of the drug play a significant role in the stability of the colloid. Mebendazole aqueous suspensions display a controllable "delayed" or "hindered" sedimentation and a very easy redispersion which may contribute to the formulation of veterinary liquid dosage forms.

In vitro and in vivo studies of a new sustained release formulation of morphine. Discrepancies between the in vitro release and the in vivo absorption in dogs.

An in vivo preclinical study has been made of the oral absorption of morphine (CAS 57-27-2) from a new sustained release formulation (morphine-Eudragit L complex, MEC), which had shown good sustained release properties in in vitro dissolution studies. The absorption of morphine from capsules filled with morphine hydrochloride trihydrate (MHT) or MEC was compared in fasted and fed dogs. Mean plasma morphine concentrations obtained after administration of MHT and MEC to fasted dogs were similar, and no statistically significant differences were found in the pharmacokinetic parameters of morphine (Cmax, Tmax and area under the plasma morphine concentration versus time curve from time zero to the last time with a detectable concentration of morphine). When MHT and MEC were administered to fed animals, mean plasma morphine concentrations were again similar for both formulations, without statistically significant differences in the pharmacokinetic parameters of morphine. These results contrast with those obtained in vitro, and indicate the limited usefulness of in vitro assays for this kind of sustained release formulations in which pH and ionic strength are important factors for drug release from the polymeric structure. The plasma morphine concentrations obtained in fed dogs were generally lower than in fasted dogs, though they were detectable for a longer time, until 10 h after dosing, in contrast to up to 6 h in fasted dogs. It is postulated that the apparently prolonged absorption of morphine in fed dogs may be due to the enterohepatic recycling of the drug (excreted in bile as glucuronide, hydrolysed back to the parent compound in the intestine, and then reabsorbed) as a consequence of gallbladder emptying induced by food.

Diclofenac salts. III. Alkaline and earth alkaline salts.

Diclofenac salts containing the alkaline and two earth alkaline cations have been prepared and characterized by scanning electron microscopy (SEM) and EDAX spectroscopy; and by thermal and thermogravimetric analysis (TGA): all of them crystallize as hydrate when precipitated from water. The salts dehydrate at room temperature and more easily on heating, but recovery the hydration, when placed in a humid environment. X-ray diffraction spectra suggest that on dehydration new peaks appear on diffractograms and the lattice of the salts partially looses crystallinity. This phenomenon is readily visible in the case of the calcium and magnesium salts, whose thermograms display a crystallization exotherm, before melting or decomposing at temperatures near or above 200 degrees C; these last salts appear to form solvates, when prepared from methanol. The thermogram of each salt shows a complex endotherm of dehydration about 100 degrees C; the calcium salt displays two endotherms, well separated at about 120 and 160 degrees C, which disappear after prolonged heating. Decomposition exotherms, before or soon after the melting, appear below 300 degrees C. The ammonium salt is thermally unstable and, when heated to start dehydration, dissociates and leaves acidic diclofenac.

In vitro evaluation of a morphine polymeric complex: flowability behavior and dissolution study.

The purpose of this research was to perform a granulometrical and flow properties study of a morphine polymeric complex and determine the influence of 3 variables--particle size of complex, pH value, and ionic strength of the dissolution medium--on the dissolution behavior. The morphine-Eudragit L complex was produced in aqueous medium from morphine hydrochloride saturated solution and Eudragit L 30D diluted until 12% wt/vol and partially neutralized (40%). To determine the rheological behavior of the complex, several rheological tests were developed: bulk and tapped densities, Hausner ratio, angle of repose, and flow rate. The results corresponding to the technological study suggest that the 100- to 250-microm fraction can be considered as free flowing powder. In relation to the dissolution behavior of the complex, the results indicate that the ionic strength has been detected as the most influencing factor when values below physiological conditions are used. In conclusion, no technological problems for the production of further solid dosage forms are expected. Furthermore, no changes in the dissolution profiles of the complex have been detected when ionic strength values are inside the physiological range.

Didanosine extended-release matrix tablets: optimization of formulation variables using statistical experimental design.

Statistical experimental design was applied to evaluate the influence of some process and formulation variables and possible interactions among such variables, on didanosine release from directly-compressed matrix tablets based on blends of two insoluble polymers, Eudragit RS-PM and Ethocel 100, with the final goal of drug release behavior optimization. The considered responses were the percent of drug released at three determined times, the dissolution efficiency at 6 h and the time to dissolve 10% of drug. Four independent variables were considered: tablet compression force, ratio between the polymers and their particle size, and drug content. The preliminary screening step, carried out by means of a 12-run asymmetric screening matrix according to a D-optimal design strategy, allowed evaluation of the effects of different levels of each variable. The drug content and the polymers ratio had the most important effect on drug release, which, moreover, was favored by greater polymers particle size; on the contrary the compression force did not have a significant effect. The Doehlert design was then applied for a response-surface study, in order to study in depth the effects of the most important variables. The desirability function was used to simultaneously optimize the five considered responses, each having a different target. This procedure allowed selection, in the studied experimental domain, of the best formulation conditions to optimize drug release rate. The experimental values obtained from the optimized formulation highly agreed with the predicted values. The results demonstrated the reliability of the model in the preparation of extended-release matrix tablets with predictable drug release profiles.

Development of sustained release matrix tablets of didanosine containing methacrylic and ethylcellulose polymers.

Didanosine, a nucleoside analog used in the treatment of acquired immuno deficiency syndrome (AIDS), has been incorporated into directly compressed monolythic matrices whose excipients were mixtures at different ratios of a methacrylic resin (Eudragit RSPM) and an ethylcellulose (Ethocel 100), both water-insoluble and pH-independent polymers. Technological characterization (drug particle morphology, mean weight, diameter, thickness and hardness of tablets) was carried out and in vitro drug release behaviour was measured using the USP basket apparatus. The effect of varying the Eudragit-Ethocel ratio, as well as the drug-polymeric matrix ratio, was evaluated. The results showed the suitability of Eudragit-Ethocel mixtures as matrix-forming material for didanosine sustained release formulations. Combination of the moderate swelling properties of Eudragit RSPM with the plastic properties of the more hydrophobic Ethocel 100 allowed suitable modulation of didanosine release.