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.

In vitro and in vivo antitumor activity of gemcitabine loaded thermosensitive liposomal nanoparticles and mild hyperthermia in pancreatic cancer.

The study was designed to explore the feasibility of increasing the delivery of gemcitabine-HCL (Gem), a poor membrane permeable and short half-life drug, through PEGylated thermosensitive liposomal nanoparticles (TSLnps) delivery system followed by mild hyperthermia (mTH) at 42°C. In vitro release pattern of Gem-TSLnps showed a significant Gem release (60%, p<0.01) at 42°C compared to that released at 37°C (29%). Cell viability and clonogenic assay demonstrated significant inhibition of MiaPaCa-2 cells growth by Gem-TSLnps + mHT compared to Gem alone. Further, IC50 value of Gem treated cells was (0.077µM) 1.2 fold higher compared to that treated with Gem-TSLnps + mHT (0.063 µM). mHT treated cells showed moderate inhibition of cell growth compared to controls. For cellular uptake studies, flow cytometric analysis and confocal imaging revealed higher uptake of Rho-TSLnps compared to Rho-PE or untreated cells. Tumor volume of mice treated with Gem alone was 1.8 fold higher compared to the group treated with Gem-TSLnps + mHT. Further, tumor regression of Gem-TSLnps + mHT treated group was significantly higher (p<0.01) compared to Gem-TSLnps or Gem. No significant elevated liver enzymes were observed when serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) level of control group was compared to that of Gem or Gem-TSLnps+mHT treated groups. However, serum level of alkaline phosphatase (ALP) of Gem or Gem-TSLnps+ mHT treated group was significantly elevated (p<0.05) when compared to the control group. In conclusion, TSLnps increased the delivery of Gem to tumor cells and also enhanced significantly the antitumor activity of Gem when combined with heat.

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.

Inhalable liposomal dry powder of gemcitabine-HCl: Formulation, in vitro characterization and in vivo studies.

Pulmonary drug delivery system facilitates local instillation of anticancer drugs to lungs which has proven to be pioneering approach for treatment of lung cancer. This approach led the groundwork for delivering liposomal formulation directly to lungs. Gemcitabine-HCl is currently considered as most effective drug for management of lung cancer. However, its application is limited owing to its metabolism by enzymes present in plasma resulting in reduced efficacy and higher toxicity. In present study, lyophilisation technique was used to convert liposomes into dry powder inhaler, which was formulated using emulsification solvent evaporation technique. The physicochemical properties including size, morphology, entrapment efficiency, loading efficiency etc. of formulated liposomes were evaluated. The prepared liposomal DPI (LDPI) formulations were then examined for solid state characteristics and aerosol performance using cascade impactor. From all the formulations prepared, the LDPI formulated using trehalose as cryoprotectant presented required properties along with desirable deposition pattern. Finally, the optimized formulation was selected for in vitro cell line studies; in vivo studies and stability study. This formulated inhalable particles offers a promising approach for the management of lung cancer through regional chemotherapy.

Enhanced bioavailability and intestinal uptake of Gemcitabine HCl loaded PLGA nanoparticles after oral delivery.

The aim of study was to formulate PLGA nanoparticles (NPs) of Gemcitabine HCl for enhanced oral bioavailability via absorption through M cells of Peyer's patches. Commercially, the drug is available as i.v. infusion due to its short half life (8-17 min), rapid metabolism and limited tumor uptake. The NPs were prepared by multiple solvent emulsification method. Optimized formulation had particle size of 166.4±2.42 nm, and entrapment of 56.48±3.63%. TEM image revealed discrete spherical structures of NPs. DSC and FTIR studies confirmed absence of interaction between drug and polymer. In vitro and ex vivo studies demonstrated sustained release from the NPs. The enhanced absorption and uptake of NPs in Caco-2 cells and in vivo absorption in intestinal tissue after oral delivery in rats was confirmed by confocal microscopy. Transport studies in Caco-2 cells confirmed 6.37-fold permeability for NPs. In vitro antiproliferative studies confirmed marked cytotoxicity of NPs on K562 leukemia cell lines. In vivo pharmacokinetic studies in rats showed 21.47-folds bioavailability enhancement from NPs. Hence, orally delivered Gemcitabine HCl loaded NPs have the potential for improving its bioavailability and avoiding side effects associated with iv infusions as well as enhancing patient compliance through "Chemotherapy at Home".