Nanotechnology - a robust tool for fighting the challenges of drug resistance in non-small cell lung cancer.

Genomic and proteomic mutation analysis is the standard of care for selecting candidates for therapies with tyrosine kinase inhibitors against the human epidermal growth factor receptor (EGFR TKI therapies) and further monitoring cancer treatment efficacy and cancer development. Acquired resistance due to various genetic aberrations is an unavoidable problem during EGFR TKI therapy, leading to the rapid exhaustion of standard molecularly targeted therapeutic options against mutant variants. Attacking multiple molecular targets within one or several signaling pathways by co-delivery of multiple agents is a viable strategy for overcoming and preventing resistance to EGFR TKIs. However, because of the difference in pharmacokinetics among agents, combined therapies may not effectively reach their targets. The obstacles regarding the simultaneous co-delivery of therapeutic agents at the site of action can be overcome using nanomedicine as a platform and nanotools as delivery agents. Precision oncology research to identify targetable biomarkers and optimize tumor homing agents, hand in hand with designing multifunctional and multistage nanocarriers that respond to the inherent heterogeneity of the tumors, may resolve the challenges of inadequate tumor localization, improve intracellular internalization, and bring advantages over conventional nanocarriers.

Reduced Cardiotoxicity of Ponatinib-Loaded PLGA-PEG-PLGA Nanoparticles in Zebrafish Xenograft Model.

Tyrosine kinase inhibitors (TKIs) are the new generation of anti-cancer drugs with high potential against cancer cells' proliferation and growth. However, TKIs are associated with severe cardiotoxicity, limiting their clinical value. One TKI that has been developed recently but not explored much is Ponatinib. The use of nanoparticles (NPs) as a better therapeutic agent to deliver anti-cancer drugs and reduce their cardiotoxicity has been recently considered. In this study, with the aim to reduce Ponatinib cardiotoxicity, Poly(D,L-lactide-co-glycolide)-b-poly(ethyleneoxide)-b-poly(D,L-lactide-co-glycolide) (PLGA-PEG-PLGA) triblock copolymer was used to synthesize Ponatinib in loaded PLGA-PEG-PLGA NPs for chronic myeloid leukemia (CML) treatment. In addition to physicochemical NPs characterization (NPs shape, size, size distribution, surface charge, dissolution rate, drug content, and efficacy of encapsulation) the efficacy and safety of these drug-delivery systems were assessed in vivo using zebrafish. Zebrafish are a powerful animal model for investigating the cardiotoxicity associated with anti-cancer drugs such as TKIs, to determine the optimum concentration of smart NPs with the least side effects, and to generate a xenograft model of several cancer types. Therefore, the cardiotoxicity of unloaded and drug-loaded PLGA-PEG-PLGA NPs was studied using the zebrafish model by measuring the survival rate and cardiac function parameters, and therapeutic concentration for in vivo efficacy studies was optimized in an in vivo setting. Further, the efficacy of drug-loaded PLGA-PEG-PLGA NPs was tested on the zebrafish cancer xenograft model, in which human myelogenous leukemia cell line K562 was transplanted into zebrafish embryos. Our results demonstrated that the Ponatinib-loaded PLGA-PEG-PLGA NPs at a concentration of 0.001 mg/mL are non-toxic/non-cardio-toxic in the studied zebrafish xenograft model.

Design of ophthalmic micelles loaded with diclofenac sodium: effect of chitosan and temperature on the block-copolymer micellization behaviour.

Diclofenac sodium 0.1% is a commonly used NSAID with well-documented clinical efficacy in reducing postoperative inflammation; however, its corneal tolerability and ophthalmic tissue bioavailability require further improvement. Advanced micellar delivery systems composed of block-copolymers and chitosan showing fine balance between the mucoadhesion and mucus permeation, capable to slip through the mucus barrier and adhere to the epithelial ocular surface, may be used to tackle both challenges. The aggregation behaviour of the block-copolymers in the presence of different additives will dramatically influence the quality attributes like particle size, particle size distribution, drug-polymer interaction, zeta potential, drug incorporation, important for the delicate balance among mucoadhesion and permeation, as well as safety and efficacy of the ophthalmic micelles. Therefore, quality by design approach and D-optimal experimental design model were used to create a pool of useful data for the influence of chitosan and the formulation factors on the block copolymer's aggregation behaviour during the development and optimization of Diclofenac loaded Chitosan/Lutrol F127 or F68 micelles. Particle size, polydispersity index, dissolution rate, FTIR and DSC studies, NMR spectroscopy, cytotoxicity, mucoadhesivity, mucus permeation studies, and bioadhesivity were assessed as critical quality attributes. FTIR and DSC studies pointed to the chaotropic effect of chitosan during the micelle aggregation. Mainly, Pluronic F68 micellization behaviour was more dramatically affected by the presence of chitosan, and self-aggregation into larger micelles with high polydispersity index was favoured at higher chitosan concentration. The optimized formulation with highest potential for ophthalmic delivery of diclofenac sodium, good cytotoxicity profile, delicate balance of the mucoadhesivity, and mucus permeation was in the design space of Chitosan/Lutrol F127 micelles.

The impact of molecular tumor profiling on the design strategies for targeting myeloid leukemia and EGFR/CD44-positive solid tumors.

Nanomedicine has emerged as a novel cancer treatment and diagnostic modality, whose design constantly evolves towards increasing the safety and efficacy of the chemotherapeutic and diagnostic protocols. Molecular diagnostics, which create a great amount of data related to the unique molecular signatures of each tumor subtype, have emerged as an important tool for detailed profiling of tumors. They provide an opportunity to develop targeting agents for early detection and diagnosis, and to select the most effective combinatorial treatment options. Alongside, the design of the nanoscale carriers needs to cope with novel trends of molecular screening. Also, multiple targeting ligands needed for robust and specific interactions with the targeted cell populations have to be introduced, which should result in substantial improvements in safety and efficacy of the cancer treatment. This article will focus on novel design strategies for nanoscale drug delivery systems, based on the unique molecular signatures of myeloid leukemia and EGFR/CD44-positive solid tumors, and the impact of novel discoveries in molecular tumor profiles on future chemotherapeutic protocols.

A Comparative Approach to Screen the Capability of Raman and Infrared (Mid- and Near-) Spectroscopy for Quantification of Low-Active Pharmaceutical Ingredient Content Solid Dosage Forms: The Case of Alprazolam.

Content uniformity is a critical attribute for potent and low-dosage formulations of active pharmaceutical ingredient (API) that, in addition to the formulation parameters, plays pivotal role during pharmaceutical development and production. However, when API content is low, implementing a vibrational spectroscopic analytical tool to monitor the content and blend uniformity remains a challenging task. The aim of this study was to showcase the potentials of mid-infrared (MIR), near-infrared (NIR), and Raman spectroscopy for quantitative analysis of alprazolam (ALZ) in a low-content powder blends with lactose, which is used as a common diluent for tablets produced by direct compression. The offered approach might be further scaled up and exploited for potential application in the process analytical technology (PAT). Partial least square and orthogonal PLS (OPLS) methodologies were employed to build the calibration models from raw and processed spectral data (standard normal variate, first and second derivatives). The models were further compared regarding their main statistical indicators: correlation coefficients, predictivity, root mean square error of estimation (RMSEE), and root mean square error of cross-validation (RMSEEcv). All statistical models presented high regression and predictivity coefficients. The RMSEEcv for the optimal models was 1.118, 0.08, and 0.059% for MIR, NIR, and Raman spectroscopy, respectively. The scarce information content extracted from the ALZ NIR spectra and the major band overlapping with those from lactose monohydrate was the main culprit of poor accuracy in the NIR model, whereas the subsampling instrumental setup (resulting in a non-representative spectral acquisition of the sample) was regarded as a main limitation for the MIR-based calibration model. The OPLS models of the Raman spectra of the powder blends manifested favorable statistical indicators for the accuracy of the calibration model, probably due to the distinctive ALZ Raman pattern resulting in the largest number of predictive spectral points that were used for the mathematical modeling. Furthermore, the Raman scattering calibration model was optimized in narrower scanning range (1700-700 cm-1) and its prediction power was evaluated (root mean square error of prediction, RMSEP = 0.03%). Thus, the Raman spectroscopy presented the most favorable statistical indicators in this comparative study and therefore should be further considered as a PAT for the quantitative determination of ALZ in low-content powder blends.

Macroalgal Polysaccharides in Biomimetic Nanodelivery Systems.

BACKGROUND: Imitating nature in the design of bio-inspired drug delivery systems resulted in several success stories. However, the practical application of biomimicry is still largely unrealized owing to the fact that we tend to copy the shape more often than the whole biology. Interesting chemistry of polysaccharides provides endless possibilities for drug complex formation and creation of delivery systems with diverse morphological and surface properties. However, the type of biological response, which may be induced by these systems, remains largely unexploited. METHODS: Considering the most current research for the given topic, in this review, we will try to present the integrative approaches for the design of biomimetic DDS's with improved therapeutic or theranostic effects based on different algal polysaccharides that exert multiple biological functions. RESULTS: Algal polysaccharides may provide building blocks for bioinspired drug delivery systems capable of supporting the mechanical properties of nanomedicines and mimicking various biological processes by molecular interactions at the nanoscale. Numerous research studies demonstrate the efficacy and safety of multifunctional nanoparticles integrating several functions in one delivery system, composed of alginate, carrageenan, ulvan, fucoidan and their derivatives, intended to be used as bioartificial microenvironment or for diagnosis and therapy of different diseases. CONCLUSION: Nanodimensional structure of polysaccharide DDS's shows substantial influence on the bioactive motifs potential availability for interaction with a variety of biomolecules and cells. Evaluation of the nano dimensional structure-activity relationship is crucial for unlocking the full potential of the future application of polysaccharide bio-mimicking DDS in modern diagnostic and therapeutic procedures.

Rational development of nanomedicines for molecular targeting in periodontal disease.

Recent advances in understanding the etiology and pathogenesis of periodontal disease and polymicrobial synergy in the dysbiotic oral microbial community endorsed novel therapeutic targets and assured further improvement in periodontal disease treatment. Moreover, understanding of the events at the molecular level inspired the researchers to alleviate the stress from the disease by applying the bottom-up approach and delivering the drugs at the site of action, using nanoscale medicines. This review is focused on promising strategies for rational design of nanopaharmaceuticals for periodontal disease treatment based on novel therapeutic targets and the potential of advanced concepts for inflammation cascade targeting. Due to their size, nanomedicines are capable to interact with the elements of the immune system through cell receptor binding and to subsequently influence specific intracellular signaling pathways activation. They might also interfere with different signaling molecules continuously involved in the disease progression, in order to abolish cell activation and block the production of proinflammatory substances. Different biomacromolecules can be trafficked to the site of action using nanomedicines for gene targeting: i) decoy oligodeoxynucleotide (ODN) for suppression of NF-κB transcription activity, ii) DNA therapeutics for modulation of cell inflammatory response and iii) siRNA for cytokine production silencing. However, despite the potential of the nanotechnology for improvement of periodontal disease treatment, the translation of nano-drug delivery systems to clinical therapy is hindered by the lack of standard procedures for proper safety and efficacy profile evaluation.

Design and biological response of doxycycline loaded chitosan microparticles for periodontal disease treatment.

The aim of this study was to develop chitosan (CS) microparticulated mucoadhesive drug delivery system (DDS) with improved therapeutic performance and biological responce. Ionotropic gelation/spray drying process was used for preparation of doxycycline hyclate (DOXY) loaded low and medium molecular weight (LMw and MMw) CS/sodium tripolyphosphate microparticles (CS/TPP MPs), further coated with ethyl cellulose (EC) using coacervation/solvent displacement technique. The relevant physico-chemical and biopharmaceutical properties were optimized using experimental design approach. Both coated and uncoated CS/TPP MPs showed high mucoadhesive potential and did not affect the viability of the tested epithelial cell line. The MPs induced slow and gradual apoptotic response in murine macrophage cell line RAW 264.7 and the observed effect depended upon formulation type and MP concentration. Biological effect of the CS-based MPs observed in our experiments point to synergism of the biological response of the carrier with the anti-inflammatory effect of DOXY.

Lactobacillus casei Encapsulated in Soy Protein Isolate and Alginate Microparticles Prepared by Spray Drying.

This article presents a novel formulation for preparation of Lactobacillus casei 01 encapsulated in soy protein isolate and alginate microparticles using spray drying method. A response surface methodology was used to optimise the formulation and the central composite face-centered design was applied to study the effects of critical material attributes and process parameters on viability of the probiotic after microencapsulation and in simulated gastrointestinal conditions. Spherical microparticles were produced in high yield (64%), narrow size distribution (d50=9.7 µm, span=0.47) and favourable mucoadhesive properties, with viability of the probiotic of 11.67, 10.05, 9.47 and 9.20 log CFU/g after microencapsulation, 3 h in simulated gastric and intestinal conditions and four-month cold storage, respectively. Fourier-transform infrared spectroscopy confirmed the probiotic stability after microencapsulation, while differential scanning calorimetry and thermogravimetry pointed to high thermal stability of the soy protein isolate-alginate microparticles with encapsulated probiotic. These favourable properties of the probiotic microparticles make them suitable for incorporation into functional food or pharmaceutical products.

Efficacy assessment of self-assembled PLGA-PEG-PLGA nanoparticles: Correlation of nano-bio interface interactions, biodistribution, internalization and gene expression studies.

The aim of our study was to develop and compare the biological performance of two types of biodegradable SN-38 loaded nanoparticles (NPs) with various surface properties, composed of low and high Mw triblock PLGA-PEG-PLGA copolymers, applying rational quality and safety by design approach. Therefore, along with the optimization of crucial physico-chemical properties and in order to evaluate the therapeutical potential and biocompatibility of prepared polymeric nanoparticles, analysis of nano-bio interactions, cell internalization, gene expression and biodistribution studies were performed. The optimized formulations, one of low Mw and one composed of high Mw PLGA-PEG-PLGA copolymer, exhibited different characteristics in terms of surface properties, particle size, zeta potential, drug loading, protein adsorption and biodistribution, which may be attributed to the variations in nano-bio interface interactions due to different NP building blocks length and Mw. On the contrary to protein adsorption and biodistribution studies, both types of NPs exhibited similar results during cell internalization and gene expression studies performed in cell culture medium containing serum proteins. This pool of useful data for internalization and efficacy as well as the notable advance in the circulation time of low Mw NPs may be further employed for shaping the potential of the designed nanocarriers.

SN-38 loading capacity of hydrophobic polymer blend nanoparticles: formulation, optimization and efficacy evaluation.

One of the most important problems in nanoencapsulation of extremely hydrophobic drugs is poor drug loading due to rapid drug crystallization outside the polymer core. The effort to use nanoprecipitation, as a simple one-step procedure with good reproducibility and FDA approved polymers like Poly(lactic-co-glycolic acid) (PLGA) and Polycaprolactone (PCL), will only potentiate this issue. Considering that drug loading is one of the key defining characteristics, in this study we attempted to examine whether the nanoparticle (NP) core composed of two hydrophobic polymers will provide increased drug loading for 7-Ethyl-10-hydroxy-camptothecin (SN-38), relative to NPs prepared using individual polymers. D-optimal design was applied to optimize PLGA/PCL ratio in the polymer blend and the mode of addition of the amphiphilic copolymer Lutrol®F127 in order to maximize SN-38 loading and obtain NPs with acceptable size for passive tumor targeting. Drug/polymer and polymer/polymer interaction analysis pointed to high degree of compatibility and miscibility among both hydrophobic polymers, providing core configuration with higher drug loading capacity. Toxicity studies outlined the biocompatibility of the blank NPs. Increased in vitro efficacy of drug-loaded NPs compared to the free drug was confirmed by growth inhibition studies using SW-480 cell line. Additionally, the optimized NP formulation showed very promising blood circulation profile with elimination half-time of 7.4 h.

PEO-PPO-PEO/Poly(DL-lactide-co-caprolactone) Nanoparticles as Carriers for SN-38: Design, Optimization and Nano-Bio Interface Interactions.

Encapsulation of extremely hydrophobic substances such as SN-38 into nanoparticles, is a promising approach to solve the solubility issue and enable drug administration. Moreover, nanocarriers' tumor homing behavior, targeted and controlled release at the site of action will optimize therapeutic potency and decrease toxicity of the incorporated drug substance. However, the enormous drug hydrophobicity might limit the capacity for encapsulation as the premature drug precipitation will contribute to fast free drug crystal growth, low drug incorporation and huge waste of the active material. In this article we defined the optimal region for manufacturing of SN-38 loaded PEO-PPO-PEO/P(DL)LCL nanoparticles (NPs) with high efficacy of encapsulation, suitable particle size and different surface properties, using D-optimal design and nanoprecipitation as production method. Further we made an approach to investigate the interactions with macromolecules at the nano-bio interface which are predetermined by the physico-chemical and surface properties of the NPs, and are important determinants for the biological identity of the nanoparticles, the potential for evasion of the physiological barriers and the efficacy of localization at the site of action. Here we present in depth analysis of the behavior of two types of nanoparticles with different surface properties through structured protein interaction and bioreactivity experiments in order to presuppose NP performance and toxicological profile in biological environment.

Synthesis and self-assembly of amphiphilic poly(acrylicacid)-poly(ɛ-caprolactone)-poly(acrylicacid) block copolymer as novel carrier for 7-ethyl-10-hydroxy camptothecin.

The process of molecular self-assembly plays a crucial role in formulation of polymeric nanoparticulated drug delivery carriers as it creates the possibility for enhanced drug encapsulation and carrier surface engineering. This study aimed to develop a novel self-assembled polymeric micelles for targeted delivery in tumor cells in order to overcome not only various drawbacks of 7-ethyl-10-hydroxy camptothecin (SN-38) but also various reported limitations of other drug delivery systems, especially low drug loading and premature release. Custom synthesized amphiphilic triblock copolymer poly(acrylic acid)-poly(ɛ-caprolactone)-poly(acrylic acid) (PAA(13)-PCL(35)-PAA(13)) was used to prepare kinetically stable micelles by nanoprecipitation and modified nanoprecipitation procedure. Core-shell micelles with diameter of 120-140 nm, negative zeta potential and satisfactory drug loading were produced. The prepared formulations were stable in pH range of 3-12 and in media with NaCl concentration <1 mol/l. Screening mixed level factorial 3 × 2(2) design identified that the process temperature as well as the type of organic solvent has influence upon the efficacy of encapsulation, particle size, dissolution rate and burst release. Fourier transform infrared and differential scanning calorimetry analyses confirmed the entrapment of the active substance into the micelles. The kinetic analysis of dissolution studies revealed that the main mechanism of drug release from the prepared formulations is Fickian diffusion. Growth inhibition studies as well as DNA fragmentation assay performed on SW-480 cell lines clearly demonstrated increased growth inhibition effect and presence of fragmented DNA in cells treated with loaded micelles compared to SN-38 solution. Altogether, these results point out to potential biomedical and clinical application of PAA-PCL-PAA systems in the future.

5-Fluorouracil-loaded PLA/PLGA PEG-PPG-PEG polymeric nanoparticles: formulation, in vitro characterization and cell culture studies.

In this study, 5-FU, a potent anticancer drug, is planned to be delivered via a new and promising drug delivery system, nanoparticles formed with hydrophobic core polymer and triblock copolymers; Poly(DL-lactic acid), Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) copolymer (PLA/PEG-PPG-PEG) and Poly(D,L-lactide-co-glycolide)/Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) copolymer (PLGA/PEG-PPG-PEG) nanoparticles. Particle size range of nanoparticles was found to be between 145 and 198 nm, which would promote the passive targeting of the nanoparticles to tumor cells based on the enhanced permeability and retention (EPR) effect. SEM images revealed all nanoparticles formulations to be spherical and without pores. Zeta potential, yield value and encapsulation efficiencies of 5-FU-loaded nanoparticles were within the range of -11.1 and -13.7 mV, 72.7-87.7% and 83.6-93.9%, respectively. Cumulative release of 5-FU was observed between 90% and 94.4% in all nanoparticle formulations by the end of 72 h, and fitness of release profiles to Higuchi model indicated matrix-controlled diffusion of the 5-FU from polymeric nanoparticles. Cell viability values of the cells treated with 5-FU-loaded nanoparticles were obtained as low as 47% and 52% with tetrazolium dye assay, suggesting that delivery of 5-FU via amphiphilic triblock copolymer nanoparticles would be a promising delivery system because of the EPR effect.

Comparative biodistribution studies of technetium-99 m radiolabeled amphiphilic nanoparticles using three different reducing agents during the labeling procedure.

Considering the confusing biodistribution data through the literature and few reported alerts as well as our preliminary biodistribution results, we decided to evaluate the interaction and interference of the commonly present (99m) Tc (technetium-99m)-stannic oxide colloid during the direct stannous chloride (99m) Tc-labeling procedure and to assess its influence on the biodistribution pattern of amphiphilic poly(lactic-co-glycolic acid) nanoparticles. In order to confirm our thesis, beside stannous chloride, we employed two different reducing agents that don't form colloidal particles. The use of sodium borohydride was previously reported in the literature, whereas sodium dithionite was adapted for the first time in the (99m) Tc direct labeling procedure for nanoparticles. The results in our paper clearly differentiate among samples with and without colloidal impurities originating from the labeling procedure with a logical follow up of the radiochemical, physicochemical evaluation, and biodistribution studies clarifying previously reported data on stannic oxide colloidal interference. (99m) Tc-nanoparticle complex labeled with sodium dithionite as reducing agent illustrated appropriate labeling efficacy, stability, and potential for further use in biodistribution studies thus providing solution for the problem of low-complex stability when sodium borohydride is used and colloidal stannic oxide interference for stannous chloride procedure.

Wheat germ agglutinin-functionalised crosslinked polyelectrolyte microparticles for local colon delivery of 5-FU: in vitro efficacy and in vivo gastrointestinal distribution.

We have previously reported the development and characterisation of wheat germ agglutinin (WGA)-functionalised chitosan-Ca-alginate (CTS-Ca-ALG) microparticles (MPs) loaded with acid-resistant particles of 5-fluorouracil (5-FU). In the present work, our goal was to evaluate the potential of these carriers for efficient treatment of colon cancer by studying in vitro permeability and cell association of 5-FU and [methyl-³H]thymidine uptake in Caco-2 cells, as well as in vivo gastrointestinal distribution. The amount of 5-FU permeated through Caco-2 cells was 15.1, 7.7 and 6.5% for 5-FU solution, CTS-Ca-ALG MPs and WGA conjugates. The concentration of 5-FU associated with Caco-2 cells was significantly greater when delivered from MPs. By incorporation of 5-FU into MPs and further decoration with WGA, an increased [methyl-³H]thymidine uptake was observed few hours after continuous drug treatment followed by significantly reduced uptake after 6 h. Gastrointestinal distribution was in favour of increased localisation and concentration of the particles in colon region.

Factorial design analysis and optimisation of alginate-Ca-chitosan microspheres.

The purpose of this study was to apply factorial design in order to determine the influence of the formulation factors and their interactions on several responses such as particle size, dissolution behaviour at pH 1.2 and pH 7.4 as well as production yield, during the development of budesonide loaded, chitosan coated Ca-alginate microparticles (MPs) intended for treatment of inflammatory diseases in the gastrointestinal tract. Produced drug-loaded MPs were spherical in shape, had smooth surfaces with low porosity and size range between 5 and 11 µm. Production yield for the formulations from the design varied from 19% to 50%. Optimisation was performed using central composite design setting the targets: particle size at 5.5 µm, maximised yield, suppressed dissolution at pH 1.2 and sustained release at pH 7.4. The optimised batches were identified with a combined desirability value of 0.967.

Chitosan coated Ca-alginate microparticles loaded with budesonide for delivery to the inflamed colonic mucosa.

Using a novel one-step spray-drying process uncoated and Eudragit S 100 coated chitosan-Ca-alginate microparticles efficiently loaded with budesonide (BDS), with bioadhesive and controlled release properties in GIT, were prepared. Microparticles were spherical with mean particle size of 4.05-5.36 microm, narrow unimodal distribution and positive surface charge. A greater extent of calcium chloride limited the swelling ratio of beads, while swelling behaviour of coated beads was mainly determined by properties of enteric coating. Comparing the release profiles of formulations, under different pH conditions, influence of polymer properties and concentration of cross-linker on the rate and extent of drug release was evident. Coating has successfully sustained release of BDS in buffers at pH 2.0 and 6.8, while providing potential for efficient release of BDS at pH 7.4. Release data kinetics indicated influence of erosion and biodegradation of polymer matrix on drug release from microparticles. Prepared formulations were stable for 12 months period at controlled ambient conditions. In conclusion coated microparticles prepared by one-step spray-drying procedure could be suitable candidates for oral delivery of BDS with controlled release properties for local treatment of inflammatory bowel diseases.

Formulation and evaluation of diazepam hydrogel for rectal administration.

Diazepam (DZP) has become a commonly used drug for treatment of acute repetitive epileptic seizures and febrile convulsions in children. Considering the advantages of rectal administration of DZP, the objective of our study was to formulate and evaluate rectal hydrogels containing DZP as a drug substance in combination with suitable co-solvents and preservatives. Prepared HPMC (hydroxypropyl methylcellulose) hydrogels containing different concentrations of DZP (2, 4 and 6 mg mL(-1)) manifested good quality in respect to physico-chemical parameters (pH value, drug content, ingredients content and viscosity), antimicrobial efficiency and microbiological quality. Under the proposed HPLC conditions, satisfactory separation of DZP and the preservatives used was achieved. In vitro release studies have shown that the total amount of DZP was released in a period of 3 h. Prepared formulations were stable for four months at 26 degrees C (ambient temperature characteristic of the 2nd climate zone).

Poly(lactide-co-glycolide) microparticles as systems for controlled release of proteins -- preparation and characterization.

Poly(DL-lactide-co-glycolide) (PDLLGA) and poly(L-lactide-co-glycolide) (PLLGA) copolymers were prepared by bulk ring opening polymerization of lactide and glycolide and characterized by GPC, FTIR, 1H NMR and DSC. Copolymers with different molar masses at a constant lactide/glycolide ratio were used for preparation of bovine serum albumin (BSA)-loaded microparticles by the double emulsion w/o/w method. The influence of the copolymer molar mass and composition on the microparticle morphology, size, yield, degradation rate, BSA-loading efficiency and BSA release profile were studied. For microparticles prepared from PDLLGA copolymers, a biphasic profile for BSA release was found and for those made from PLLGA copolymers the release profile was typically triphasic; both of them were characterized by high initial burst release. Possible reasons for such behavior are discussed.