Atovaquone-loaded nanocapsules: influence of the nature of the polymer on their in vitro characteristics

Development of Essential Oil-Loaded Polymeric Nanocapsules as Skin Delivery Systems: Biophysical Parameters and Dermatokinetics Ex Vivo Evaluation

Essential oils (EOs) are natural antioxidant alternatives that reduce skin damage. However, EOs are highly volatile; therefore, their nanoencapsulation represents a feasible alternative to increase their stability and favor their residence time on the skin to guarantee their effect. In this study, EOs of Rosmarinus officinalis and Lavandula dentata were nanoencapsulated and evaluated as skin delivery systems with potential antioxidant activity. The EOs were characterized and incorporated into polymeric nanocapsules (NC-EOs) using nanoprecipitation. The antioxidant activity was evaluated using the ferric thiocyanate method. The ex vivo effects on pig skin were evaluated based on biophysical parameters using bioengineering techniques. An ex vivo dermatokinetic evaluation on pig skin was performed using modified Franz cells and the tape-stripping technique. The results showed that the EOs had good antioxidant activity (>65%), which was maintained after nanoencapsulation and purification. The nanoencapsulation of the EOs favored its deposition in the stratum corneum compared to free EOs; the highest deposition rate was obtained for 1,8-cineole, a major component of L. dentata, at 1 h contact time, compared to R. officinalis with a major deposition of the camphor component. In conclusion, NC-EOs can be used as an alternative antioxidant for skin care.

PEGylated and functionalized polylactide-based nanocapsules: An overview

Polymeric nanocapsules (NC) are versatile mixed vesicular nanocarriers, generally containing a lipid core with a polymeric wall. They have been first developed over four decades ago with outstanding applicability in the cosmetic and pharmaceutical fields. Biodegradable polyesters are frequently used in nanocapsule preparation and among them, polylactic acid (PLA) derivatives and copolymers, such as PLGA and amphiphilic block copolymers, are widely used and considered safe for different administration routes. PLA functionalization strategies have been developed to obtain more versatile polymers and to allow the conjugation with bioactive ligands for cell-targeted NC. This review intends to provide steps in the evolution of NC since its first report and the recent literature on PLA-based NC applications. PLA-based polymer synthesis and surface modifications are included, as well as the use of NC as a novel tool for combined treatment, diagnostics, and imaging in one delivery system. Furthermore, the use of NC to carry therapeutic and/or imaging agents for different diseases, mainly cancer, inflammation, and infections is presented and reviewed. Constraints that impair translation to the clinic are discussed to provide safe and reproducible PLA-based nanocapsules on the market. We reviewed the entire period in the literature where the term "nanocapsules" appears for the first time until the present day, selecting original scientific publications and the most relevant patent literature related to PLA-based NC. We presented to readers a historical overview of these Sui generis nanostructures.

Polymeric versus lipid nanocapsules for miconazole nitrate enhanced topical delivery: in vitro and ex vivo evaluation

Nanocapsules can be equated to other nanovesicular systems in which a drug is entrapped in a void containing liquid core surrounded by a coat. The objective of the present study was to investigate the potential of polymeric and lipid nanocapsules (LNCs) as innovative carrier systems for miconazole nitrate (MN) topical delivery. Polymeric nanocapsules and LNCs were prepared using emulsification/nanoprecipitation technique where the effect of poly(ε-caprolactone (PCL) and lipid matrix concentrations with respect to MN were assessed. The resulted nanocapsules were examined for their average particle size, zeta potential, %EE, and in vitro drug release. Optimum formulation in both polymeric and lipidic nanocapsules was further subjected to anti-fungal activity and ex vivo permeation tests. Based on the previous results, nanoencapsulation strategy into polymeric and LNCs created formulations of MN with slow biphasic release, high %EE, and improved stability, representing a good approach for the delivery of MN. PNCs were best fitted to Higuchi’s diffusion while LNCs followed Baker and Lonsdale model in release kinetics. The encapsulated MN either in PNCs or LNCs showed higher cell viability in WISH amniotic cells in comparison with free MN. PNCs showed less ex vivo permeation. PNCs were accompanied by high stability and more amount drug deposition (32.2 ± 3.52 µg/cm²) than LNCs (12.7 ± 1.52 µg/cm²). The antifungal activity of the PNCs was high 19.07 mm compared to 11.4 mm for LNCs. In conclusion, PNCs may have an advantage over LNCs by offering dual action for both superficial and deep fungal infections.

Lyophilization of Nanocapsules: Instability Sources, Formulation and Process Parameters

Polymeric nanocapsules have gained more and more interest in the medical sciences. Their core-shell structure offers numerous advantages, especially regarding their use as drug delivery systems. This review begins by presenting the different intrinsic sources of the instability of nanocapsules. The physical and chemical potential instabilities of nanocapsules reduce their shelf-life and constitute a barrier to their clinical use and to their commercialization. To overcome these issues, lyophilization is often used as a process of choice in the pharmaceutical industry especially when labile compounds are used. The state of the art of lyophilization nanocapsules is reviewed. The formulation properties and the process parameters are discussed for a complete understanding of their impact on the stability and storage of the final dried product. To assess the quality of the dried product, various characterization methods are also discussed.

Intra-articular multifunctional celecoxib loaded hyaluronan nanocapsules for the suppression of inflammation in an osteoarthritic rat model

Direct intra-articular delivery of drugs to osteoarthritic joints offers the possibility of delivering high drug concentrations at the site of action as well as decreasing long term associated side effects after oral drug delivery. So in the current work, we aimed to improve the osteoarthritic therapeutic efficacy of the non-steroidal anti-inflammatory drug; celecoxib, through the formulation of drug loaded hyaluronan nanocapsules. The proposed formulation aimed to combine the beneficial viscosupplemental properties of hyaluronic acid with the pharmacological, anti-inflammatory, effect of celecoxib in a novel drug carrier for intra-articular delivery. The proposed nanocapsules were prepared by the nanoprecipitation method. Several formulation variables were studied aiming at optimizing the nanocapsules' size, polydispersity index and celecoxib entrapment efficiency %. The optimized hyaluronan nanocapsules formulation showed a size of 254.9 ± 3.06 nm, which is appropriate for the intra-articular delivery of celecoxib, high entrapment efficiency% of 97.98% ± 0.19, and prolonged celecoxib release for almost one week. The transmission electron microscope images revealed spherical shape of the nanocapsules with distinct shell and core structure. The in-vivo evaluation of the anti-osteoarthritic activity of the optimized hyaluronan nanocapsules formulation showed the superiority of the prepared celecoxib nanocapsules compared to celecoxib suspension in a Monoiodoacetate induced osteoarthritic rat model, regarding histological, swelling and immunohistochemical parameters of osteoarthritis.

Antifungal and Mucoadhesive Properties of an Orally Administered Chitosan-Coated Amphotericin B Nanostructured Lipid Carrier (NLC)

Surface-modified nanostructured lipid carriers (NLC) represent a promising mode of drug delivery used to enhance retention of drugs at absorption site. Formulated chitosan-coated amphotericin-B-loaded NLC (ChiAmp NLC) had a size of 394.4 ± 6.4 nm, encapsulation and loading efficiencies of 86.0 ± 3% and 11.0 ± 0.1% respectively. Amphotericin-B release from NLCs was biphasic with no changes in physical properties upon exposure to simulated gastrointestinal conditions. Antifungal properties of Amphotericin-B and ChiAmpB NLC were comparable but ChiAmpB NLC was twice less toxic to red blood cells and ten times safer on HT-29 cell lines. In vitro mucoadhesion data were observed ex vivo, where ChiAmpB NLC resulted in higher retention within the small intestine compared to the uncoated formulation. The data strongly offers the possibility of orally administering a non-toxic, yet effective Amphotericin-B nanoformulation for the treatment of systemic fungal infections.

Tamoxifen citrate-loaded poly(d,l) lactic acid nanoparticles: Evaluation for their anticancer activity in vitro and in vivo

The optimization of tamoxifen citrate entrapment and its release from biodegradable poly(d,l) lactic acid nanoparticles are prepared by modified spontaneous emulsification solvent diffusion method. Since the addition of tamoxifen citrate induces the formation of drug crystals from nanoparticle suspension the influence of several parameters on tamoxifen citrate encapsulation was investigated. In vitro studies for cytotoxicity, DNA ladder, and the expression of Bcl-2-Bax expression were also investigated for MCF-7 and MDA-MB-231 cells after the addition of tamoxifen citrate alone and tamoxifen citrate-poly(d,l) lactic acid-nanoparticles (encapsulated tamoxifen citrate). From results, it was noticed that the size and zeta potential of the drug loaded nanoparticles were not differed much in their physicochemical properties from drug free counterparts. The drug-loaded and drug-free nanoparticles exhibited size of in between 271.4 and 282.7 nm and zeta potential of -34 to -27.4 mV, respectively. There was significant increase in drug incorporation in the particles noticed in dichloromethane + methanol system in comparison to acetone + methanol and ethyl acetate + methanol systems. The drug was partly released from the nanoparticles after 48 h of incubation at 37℃. From Fourier transform infrared spectroscopy and differential scanning calorimetry data demonstrated drug-polymer characteristics within the nanoparticles and unincorporated drug that appeared in the form of crystals from polarized microscopic study. MCF-7 and MDA-MB-231 cells were more sensitive to tamoxifen citrate-poly(d,l) lactic acid-nanoparticles than tamoxifen citrate alone. DNA ladder and the expression of Bax to Bcl-2 ratio were much higher in tamoxifen citrate encapsulated in nanoparticles than that in tamoxifen citrate alone. These results demonstrated the feasibility of encapsulation of tamoxifen citrate and its enhanced efficiency in vitro and in vivo studies.

Controlled Drug Release from Pharmaceutical Nanocarriers

Nanocarriers providing spatiotemporal control of drug release contribute to reducing toxicity and improving therapeutic efficacy of a drug. On the other hand, nanocarriers face unique challenges in controlling drug release kinetics, due to the large surface area per volume ratio and the short diffusion distance. To develop nanocarriers with desirable release kinetics for target applications, it is important to understand the mechanisms by which a carrier retains and releases a drug, the effects of composition and morphology of the carrier on the drug release kinetics, and current techniques for preparation and modification of nanocarriers. This review provides an overview of drug release mechanisms and various nanocarriers with a specific emphasis on approaches to control the drug release kinetics.

Formulation development, stability and anticancer efficacy of core-shell cyclodextrin nanocapsules for oral chemotherapy with camptothecin

BACKGROUND

The aim of this study was to design and evaluate hybrid cyclodextrin (CD) nanocapsules intended for the oral delivery of the anticancer agent camptothecin (CPT) in order to maintain drug stability in the body and to improve its eventual bioavailability. For this reason, an amphiphilic cyclodextrin (CD) derivative per-modified on the primary face 6OCAPRO was used as core molecule to form nanocapsules with the nanoprecipitation technique. Nanocapsules were further coated with the cationic polymer chitosan to improve the cellular uptake and interaction with biological membranes through positive surface charge. Nanocapsules were evaluated for their in vitro characteristics such as particle size, zeta potential, drug loading and release profiles followed by cell culture studies with the MCF-7 and Caco-2 cell line evaluating their anticancer efficacy and permeability. The CD nanocapsules were imaged by scanning electron microscopy (SEM). The concentration of CPT entrapped in nanocapsules was determined by reversed phase HPLC. The in vitro release study of CPT was performed with a dialysis bag method under sink conditions mimicking the gastric and intestinal pH. The hydrolytic stability of CPT in nanocapsules was investigated in simulated gastric and intestinal fluids (SGF, SIF).

RESULTS

The mean particle sizes of both anionic and cationic CPT-loaded nanocapsules were in the range of 180-200 nm with polydispersity indices lower than 0.400 indicating monodisperse size distribution of nanocapsules with favourable potential for intracellular drug delivery to tumour cells. Surface charges of anionic and cationic nanocapsules were demonstrated as -21 mV and +18 mV, respectively. The stability of CPT in simulated release media, SGF and SIF were maintained suggesting the improved protection of the drug molecule from rapid hydrolysis degradation or gastrointestinal pH in nanocapsule oily core. Furthermore CD nanocapsules showed higher anticancer efficacy than CPT solution against the MCF-7 cell line. Permeation of CPT across Caco-2 cells was found to be 3 fold higher when incorporated in hybrid CD nanocapsules compared with a DMSO solution.

CONCLUSION

Oral CD nanocapsules indicating increased oral bioavailability might be a promising strategy to maintain the physiological stability and to improve the oral bioavailability of problematic anticancer drugs such as CPT which may contribute to patient quality of life and drug efficacy in cancer therapy.

Stealth Amphotericin B nanoparticles for oral drug delivery: In vitro optimization

Purpose

Amphotericin B (AmB) is an effective anti-fungal and anti-leishmanial agent. However, AmB has low oral bioavailability (0.3%) and adverse effects (e.g., nephrotoxicity). The objectives of this study were to improve the oral bioavailability by entrapping AmB in pegylated (PEG) poly lactide co glycolide copolymer (PLGA–PEG) nanoparticles (NPs). The feasibility of different surfactants and stabilizers on the mean particle size (MPS) and entrapment efficiency were also investigated.

Materials and methods

NPs of AmB were prepared by a modified emulsification diffusion method employing a vitamin E derivative as a stabilizer. Physicochemical properties and particle size characterization were evaluated using Fourier Transform Infra-Red spectroscopy (FTIR), differential scanning calorimetry, scanning electron microscopy and transmission electron microscopy. Moreover, in vitro dissolution profiles were performed for all formulated AmB NPs.

Results

MPS of the prepared spherical particles of AmB ranged from 26.4 ± 2.9 to 1068 ± 489.8 nm. An increased stirring rate favored AmB NPs with a smaller MPS. There was a significant reduction in MPS, drug content and drug release, when AmB NPs were prepared using the diblock polymer PLGA–PEG with 15% PEG. Addition of three emulsifying agents poly vinyl pyrrolidone (PVP), Vitamin E (TPGS) and pluronic F-68 to AmB formulations led to a significant reduction in particle size and increase in drug entrapment efficiency (DEE) compared to addition of PVP alone. FTIR spectroscopy demonstrated a successful loading of AmB to pegylated PLGA–PEG copolymers. PLGA–PEG copolymer entrapment efficiency of AmB was increased up to 56.7%, with 92.7% drug yield. After a slow initial release, between 20% and 54% of AmB was released in vitro within 24 h phosphate buffer containing 2% sodium deoxycholate and were best fit Korsmeyer–Peppas model. In conclusion, PLGA–PEG diblock copolymer with 15% PEG produced a significant reduction (>70%) in MPS with highest drug content. The percentage of PEG in the copolymer and the surfactant/stabilizer used had a direct effect on AmB release in vitro, entrapment efficiency and MPS. These developed formulations are feasible, effective and improved alternatives to other carriers for oral delivery of AmB.

Optimisation of rosemary oil encapsulation in polycaprolactone and scale-up of the process

Rosemary essential oil (REO) has many biological activities, such as antioxidant, anticarcinogenic, cognition-enhancing, analgesic and antimicrobial activities. The aim of this study was to prepare, at laboratory scale and larger scale, nanoencapsulating REO in order to reduce its volatilisation, light sensitivity and to enhance its water solubility. The nanoprecipitation method was applied to prepare polycaprolactone (PCL)-based nanocapsules loaded with REO at laboratory scale and then the optimal formulation obtained was scaled-up (×6) using the membrane contactor technique. The effect of several parameters, such as the evaporation method, the type of emulsifiers and the amount of the formulation products (PCL, REO, emulsifiers, etc.) on the REO-loaded nanocapsules properties (mean size, polydispersity index (PdI), zeta potential and REO loss) was evaluated at laboratory scale in order to obtain the optimal formulation. REO-loaded nanocapsules obtained from nanoprecipitation presented a nanometric mean size (220 ± 10 nm) with a PdI below 0.25, indicating an adequate homogeneity of the system, a negative zeta potential (-19.9 ± 4.6 mV) and a high encapsulation efficiency (∼99% for the major components). In addition, the membrane contactor technique gave similar results using an adequate pressure of the organic phase (0.8-1.2 bar). It is then suggested that the nanoprecipitation method can be suitable for the preparation of essential oil-loaded nanocapsules.

Polyethylene glycol conjugated polymeric nanocapsules for targeted delivery of quercetin to folate-expressing cancer cells in vitro and in vivo

In this work we describe the formulation and characterization of chemically modified polymeric nanocapsules incorporating the anticancer drug, quercetin, for the passive and active targeting to tumors. Folic acid was conjugated to poly(lactide-co-glycolide) (PLGA) polymer to facilitate active targeting to cancer cells. Two different methods for the conjugation of PLGA to folic acid were employed utilizing polyethylene glycol (PEG) as a spacer. Characterization of the conjugates was performed using FTIR and (1)H NMR studies. The PEG and folic acid content was independent of the conjugation methodology employed. PEGylation has shown to reduce the size of the nanocapsule; moreover, zeta-potential was shown to be polymer-type dependent. Comparative studies on the cytotoxicity and cellular uptake of the different formulations by HeLa cells, in the presence and absence of excess folic acid, were carried out using MTT assay and Confocal Laser Scanning Microscopy, respectively. Both results confirmed the selective uptake and cytotoxicity of the folic acid targeted nanocapsules to the folate enriched cancer cells in a folate-dependent manner. Finally, the passive tumor accumulation and the active targeting of the nanocapsules to folate-expressing cells were confirmed upon intravenous administration in HeLa or IGROV-1 tumor-bearing mice. The developed nanocapsules provide a system for targeted delivery of a range of hydrophobic anticancer drugs in vivo.

Influence of process and formulation parameters on the formation of submicron particles by solvent displacement and emulsification-diffusion methods critical comparison

Solvent displacement and emulsification-diffusion are the methods used most often for preparing biodegradable submicron particles. The major difference between them is the procedure, which results from the total or partial water miscibility of the organic solvents used. This review is devoted to a critical and a comparative analysis based on the mechanistic aspects of particle formation and reported data on the influence of operating conditions, polymers, stabilizing agents and solvents on the size and zeta-potential of particles. In addition, a systematic study was carried out experimentally in order to obtain experimental data not previously reported and compare the data pertaining to the different methods. Thus the discussion of the behaviors reported in the light of the results obtained from the literature takes into account a wide range of theoretical and practical information. This leads to discussion on the formation mechanism of the particles and provides criteria for selecting the adequate method and raw materials for satisfying specific objectives in submicron particle design.

Formulation of chitosan-TPP-pDNA nanocapsules for gene therapy applications

The encapsulation of DNA inside nanoparticles meant for gene delivery applications is a challenging process where several parameters need to be modulated in order to design nanocapsules with specific tailored characteristics. The purpose of this study was to investigate and improve the formulation parameters of plasmid DNA (pDNA) loaded in chitosan nanocapsules using tripolyphosphate (TPP) as polyanionic crosslinker. Nanocapsule morphology and encapsulation efficiency were analyzed as a function of chitosan degree of deacetylation and chitosan-TPP ratio. The manipulation of these parameters influenced not only the particle size but also the encapsulation and release of pDNA. Consequently the transfection efficiency of the nanoparticulated systems was also enhanced with the optimization of the particle characteristics. Overall, the differently formulated nanoparticulated systems possess singular properties that can be employed according to the desired gene delivery application.

Development of a nanoparticulate formulation of diminazene to treat African trypanosomiasis

There is a real need to develop new therapeutic strategies for African trypanosomiasis infections. In our study, we developed a new drug delivery system of diminazene (DMZ), a trypanocidal drug registered for veterinary use. This drug candidate presents a limited efficacy, a poor affinity for brain tissue and instability. The development of colloidal formulations based on a porous cationic nanoparticle with an oily core ((70)DGNP(+)), has potentially two advantages: stabilization of the drug and potential targeting of the parasite. We analyzed two processes of drug loading: in process (DMZ was added during the preparation of (70)DGNP(+) at 80 °C) and post-loading (DMZ was mixed with a (70)DGNP(+) solution at room temperature). Poor stability of the drug was observed using the in process technique. When using the post-loading technique over 80% drug entrapment efficiency was obtained at a ratio of DMZ:phospholipids (wt:wt) < 5%. Moreover, DMZ loaded into (70)DGNP(+) was found to be protected against oxidation and was stable for at least six months at 4 °C. Finally, in vitro tests on T.b. brucei showed an increased efficacy of DMZ loaded in (70)DGNP(+).

A detailed analysis of biodegradable nanospheres by different techniques--a combined approach to detect particle sizes and size distributions

Poly(d,l-lactide-co-glycolide) nanosupensions as intravenous nanosphere systems were produced by solvent deposition in aqueous Poloxamer 188 solutions. Light scattering techniques were applied to these colloidal systems to characterize particle sizes. Regularly shaped spherical particles were received as proved by freeze fracture replica and small-angle X-ray scattering (SAXS). SAXS was performed using intensive synchrotron radiation. Particle sizes were calculated from the small-angle part of scattering curve that were in good agreement with z-average values received from photon correlation spectroscopy (PCS). The flow field-flow fractionation (FlFFF) fractograms in combination with multi-angle light scattering (MALS) allowed an easy detection of maximum particle sizes what is most important for parenteral systems. Furthermore, high quality size distributions were received due to the separation step prior to size characterization. The calculated average size values exhibited a good correlation with z-averages determined by PCS. Only for suspensions of broader size distributions, higher deviations were observed. Comparing particle sizes with and without Poloxamer, differences in diameters resulted that were quantified. The additional Poloxamer shell was not able to be removed by an intensive washing during FlFFF focusing and separation. Especially FlFFF/MALS proved to be a valuable tool to characterize the pharmaceutical nanosuspensions in detail what is of great importance especially for controlled drug delivery systems.

Novel functionalized biodegradable polymers for nanoparticle drug delivery systems

We have prepared and screened a library of novel functionalized polymers for development of nanoparticle drug delivery systems. The polymer backbone consisting of two ester-linked, nontoxic, biological monomers, glycerol and adipic acid, was prepared using a hydrolytic enzyme. The specificity of the chosen enzyme yields a linear polymer with one free pendant hydroxyl group per repeat unit, which can be further functionalized. This protocol gives control over the backbone polymer molecular weight, together with the ability to incorporate various amounts of different fatty acyl substituents. These functionalized polymers are able to self-assemble into well-defined small particles of high homogeneity with a very low toxicity. They are able to incorporate a water soluble drug, dexamethasone phosphate, with a high efficiency and drug loading which varies with the polymer specification. The above characteristics strongly suggest that these polymers could be developed into useful nanoparticulate drug delivery systems.

Core-shell structure of Miglyol/poly(d,l-lactide)/Poloxamer nanocapsules studied by small-angle neutron scattering

The contrast variation technique in small angle neutron scattering (SANS) was used to investigate the inner structure of nanocapsules on the example of poly(D,L-lactide) (PLA) nanocapsules. The determination of the PLA and Poloxamer shell thickness was the focus of this study. Highest sensitivity on the inner structure of the nanocapsules was obtained when the scattering length density of the solvent was varied between the one of the Miglyol core and the PLA shell. According to the fit data the PLA shell thickness was 9.8 nm. The z-averaged radius determined by SANS experiments correlated well with dynamic light scattering (DLS) results, although DLS values were systematically slightly higher than the ones measured by SANS. This could be explained by taking into account the influence of Poloxamer attached to the nanocapsules surface. For a refined fit model with a second shell consisting of Poloxamer, SANS values and DLS values fitted well with each other. The characterization method presented here is significant because detailed insights into the nanocapsule and the Poloxamer shell were gained for the first time. This method could be used to develop strategies for the optimization of the shell properties concerning controlled release and to study changes in the shell structure during degradation processes.

Poly-epsilon-caprolactone microspheres and nanospheres: an overview

Poly-epsilon-caprolactone (PCL) is a biodegradable, biocompatible and semicrystalline polymer having a very low glass transition temperature. Due to its slow degradation, PCL is ideally suitable for long-term delivery extending over a period of more than one year. This has led to its application in the preparation of different delivery systems in the form of microspheres, nanospheres and implants. Various categories of drugs have been encapsulated in PCL for targeted drug delivery and for controlled drug release. Microspheres of PCL either alone or of PCL copolymers have been prepared to obtain the drug release characteristics. This article reviews the advancements made in PCL-based microspheres and nanospheres with special reference to the method of preparation of these and their suitability in developing effective delivery systems.

Optimization of polylactic-co-glycolic acid nanoparticles containing itraconazole using 2(3) factorial design

This study investigated the utility of a 2(3) factorial design and optimization process for polylactic-co-glycolic acid (PLGA) nanoparticles containing itraconazole with 5 replicates at the center of the design. Nanoparticles were prepared by solvent displacement technique with PLGA X1 (10, 100 mg/mL), benzyl benzoate X2 (5, 20 microg/mL), and itraconazole X3 (200, 1800 microg/mL). Particle size (Y1), the amount of itraconazole entrapped in the nanoparticles (Y2), and encapsulation efficiency (Y3) were used as responses. A validated statistical model having significant coefficient figures (P < .001) for the particle size (Y1), the amount of itraconazole entrapped in the nanoparticles (Y2), and encapsulation efficiency (Y3) as function of the PLGA (X1), benzyl benzoate (X2), and itraconazole (X3) were developed: Y1 = 373.75 + 66.54X1+ 52.09X2 + 105.06X3 - 4.73X1X2 + 46.30X1X3; Y2 = 472.93 + 73.45X1 + 169.06X2 + 333.03X3 + 62.40X1X3 + 141.49X2X3; Y3 = 57.36 + 6.53X1 + 15.52X2 - 12.59X3 + 1.01X1X3 + 1.73X2X3. X1, X2, and X3 had a significant effect (P < .001) on Y1, Y2, and Y3. The particle size, the amount of itraconazole entrapped in the nanoparticles, and the encapsulation efficiency of the 4 formulas were in agreement with the predictions obtained from the models (P < .05). An overlay plot for the 3 responses shows the boundary in which Y1 shows the boundary in which a number of combinations of concentration of PLGA, benzyl benzoate, and itraconazole will result in a satisfactory process. Using the desirability approach with the same constraints, the solution composition having the highest overall desirability (D = 0.769) was 10 mg/mL of PLGA, 16.94 microg/mL of benzyl benzoate, and 1001.01 microg/mL of itraconazole. This approach allowed the selection of the optimum formulation ingredients for PLGA nanoparticles containing itraconazole of 500 microg/mL.

Therapeutic evaluation of free and nanocapsule-encapsulated atovaquone in the treatment of murine visceral leishmaniasis

The activities of free atovaquone (ATV) and of poly(D,L-lactide) nanocapsules loaded with the drug, in the treatment of mice with visceral leishmaniasis caused by Leishmania infantum, were compared. Each mouse was infected intravenously with 2x10(7) promastigotes, on day 0. On days 15, 17 and 19, most of the infected mice were treated either with free ATV, in a dimethylsulphoxide/cremophor/water mixture, or with the ATV-loaded nanocapsules (at, respectively, 0.2-1.6 and 0.125-1.0 mg ATV/kg, on each treatment day). The rest of the mice were left untreated, as controls. All the mice were killed on day 21 and dissected so that their livers and spleens could be weighed. The liver parasite burdens, evaluated using the Stauber method, indicated that the ATV-loaded nanocapsules were significantly more effective than the free drug. In nanocapsules, for example, a total dose of 3.0 mg ATV/kg reduced liver burdens by 71.3%, whereas treatment with a higher total dose of the free drug (4.8 mg/kg) only cut the number of liver parasites by 34.4%. The dose-response data indicated that livers would have been cleared of parasites if the nanocapsule preparation had been given as three doses each equivalent to 3 mg ATV/kg, whereas the maximum suppression possible with the free drug would have been about 61%, whatever the dose.