Development and in vitro evaluation of a self-emulsifying drug delivery system (SEDDS) for oral vancomycin administration.

The aim of this study was to develop a self-emulsifying drug delivery system (SEDDS) containing the glycopeptide antibiotic vancomycin (VAN) with improved intestinal mucosa permeating properties in order to increase oral drug absorption. VAN was effectively incorporated into SEDDS increasing the lipophilicity of the drug via hydrophobic ion pairing (HIP) with cetyltrimethylammonium bromid (CTAB). Newly developed SEDDS formulations containing VAN/CTAB complex were characterized with respect to droplet size, polydispersity index and zeta potential. Furthermore, permeating properties were investigated in porcine intestinal mucus using Transwell setup and on freshly excised porcine intestinal mucosa utilizing Ussing-type chamber. In addition, minimum inhibitory concentration (MIC) of VAN/CTAB-SEDDS against Staphylococcus aureus was evaluated. The developed formulations F1 (25% Capmul 808G EP/NF, 37.5% Cremophor RH 40, 37.5%), F2 (26.5% Capmul 808G EP/NF, 33.2% Cremophor RH 40, 13.8% Transcutol, 26.5% DMSO) and F3 (28.8% Captex 8000, 35% Cremophor EL, 20% Transcutol, 16.2% DMSO) with a mean droplet size of 14 nm, 15 nm and 153 nm, respectively, exhibited improved ability to permeate porcine intestinal mucosal barrier. F1-VAN/CTAB showed 219-fold, F2-VAN/CTAB 46-fold and F3-VAN/CTAB 63-fold higher permeation of VAN through the mucus layer after 4 h in comparison to free VAN. Moreover, all formulations demonstrated a 4-8-fold improvement in permeation of intestinal mucosa compared to free VAN solution. Additionally, F2-VAN/CTAB with a MIC of 0.313 mg/L showed higher effectivity against S. aureus (ATCC® 29213) compared to free VAN. According to these results, HIP combined with SEDDS should be taken into consideration as promising tool for oral antibiotic delivery.

Gemcitabine hydrochloride microspheres used for intravesical treatment of superficial bladder cancer: a comprehensive in vitro/ex vivo/in vivo evaluation.

INTRODUCTION: Bladder cancer is responsible for more than 130,000 deaths annually worldwide. Intravesical delivery of chemotherapeutic agents provides effective drug localization to the target area to reduce toxicity and increase efficacy. This study aimed to develop an intravesical delivery system of gemcitabine HCl (Gem-HCl) to provide a sustained-release profile, to prolong residence time, and to enhance its efficiency in the treatment of bladder cancer. MATERIALS AND METHODS: For this purpose, bioadhesive microspheres were successfully prepared with average particle size, encapsulation efficiency, and loading capacity of 98.4 µm, 82.657%±5.817%, and 12.501±0.881 mg, respectively. For intravesical administration, bioadhesive microspheres were dispersed in mucoadhesive chitosan or in situ poloxamer gels and characterized in terms of gelation temperature, viscosity, mechanical, syringeability, and bioadhesive and rheological properties. The cytotoxic effects of Gem-HCl solution, Gem-HCl microspheres, and Gem-HCl microsphere-loaded gel formulations were evaluated in two different bladder cancer cell lines: T24 (ATCC HTB4TM) and RT4 (ATCC HTB2TM). RESULTS: According to cell-culture studies, Gem-HCl microsphere-loaded poloxamer gel was more cytotoxic than Gem-HCl microsphere-loaded chitosan gel. Antitumor efficacy of newly developed formulations were investigated by in vivo studies using bladder-tumor-induced rats. CONCLUSION: According to in vivo studies, Gem-HCl microsphere-loaded poloxamer gel was found to be an effective and promising alternative for current intravesical delivery-system therapies.

Mucoadhesive self-emulsifying delivery systems for ocular administration of econazole.

AIM: Development of mucoadhesive self-emulsifying drug delivery systems (SEDDS) providing a prolonged ocular residence time for poorly soluble active pharmaceutical ingredient. METHODS: l-Cysteine was covalently linked to 6-mercaptonicotinamide. The obtained ligand, Cysteine-6-mercaptonicotinamide (Cys-6-MNA) was attached to Eudragit® L100-55 via a carbodiimide mediated amide bond formation. The resulting entirely S-protected thiolated Eudragit® L100-55 was characterized regarding the degree of modification as well as stability toward oxidation in the presence of strong oxidizing agent (H2O2). The S-protected thiolated Eudragit® L100-55 was incorporated into SEDDS via hydrophobic ion pairing with benzalkonium chloride (BAK) in a concentration of 2% (m/m). S-protected thiolated Eudragit® L100-55-BAK ion pair SEDDS (S-protected thiolated EU-BAK SEDDS) were characterized regarding their physicochemical and mucoadhesive properties. Econazole nitrate (EN) was incorporated into SEDDS in concentration of 1% (m/m) and in vitro drug release was assessed. Furthermore, toxicity study was performed on procine corneas via resazurin assay. RESULTS: The entirely S-protected thiolated Eudragit® L100-55 exhibited 282 ±â€¯78.25 µmol of MNA per gram of polymer. Ellman's test confirmed no free thiol groups and stability study showed no significant increase in dynamic viscosity overtime. The droplet size of developed SEDDS in simulated lacrimal fluid was below 100 nm with polydispersity index below 0.3. S-protected thiolated EU-BAK SEDDS exhibited 2.5-fold higher mucoadhesive properties than blank SEDDS on ocular mucosa. S-protected thiolated EU-BAK SEDDS showed sustained EN release over period of 8 h and no pronounced corneal toxicity in 0.5% (m/v) concentration. CONCLUSION: Accordingly, these mucoadhesive SEDDS can be considered as promising ocular delivery system for EN.

Design and evaluation of an intravesical delivery system for superficial bladder cancer: preparation of gemcitabine HCl-loaded chitosan-thioglycolic acid nanoparticles and comparison of chitosan/poloxamer gels as carriers.

This study aimed to develop an intravesical delivery system of gemcitabine HCl for superficial bladder cancer in order to provide a controlled release profile, to prolong the residence time, and to avoid drug elimination via urination. For this aim, bioadhesive nanoparticles were prepared with thiolated chitosan (chitosan-thioglycolic acid conjugate) and were dispersed in bioadhesive chitosan gel or in an in situ gelling poloxamer formulation in order to improve intravesical residence time. In addition, nanoparticle-loaded gels were diluted with artificial urine to mimic in vivo conditions in the bladder and were characterized regarding changes in gel structure. The obtained results showed that chitosanthioglycolic acid nanoparticles with a mean diameter of 174.5±3.762 nm and zeta potential of 32.100±0.575 mV were successfully developed via ionotropic gelation and that the encapsulation efficiency of gemcitabine HCl was nearly 20%. In vitro/ex vivo characterization studies demonstrated that both nanoparticles and nanoparticle-loaded chitosan and poloxamer gels might be alternative carriers for intravesical administration of gemcitabine HCl, prolonging its residence time in the bladder and hence improving treatment efficacy. However, when the gel formulations were diluted with artificial urine, poloxamer gels lost their in situ gelling properties at body temperature, which is in conflict with the aimed formulation property. Therefore, 2% chitosan gel formulation was found to be a more promising carrier system for intravesical administration of nanoparticles.