A mucoadhesive in situ gel delivery system for paclitaxel

A thermosensitive chitosan hydrogel: An attempt for the nasal delivery of dimethyl fumarate

Dimethyl fumarate (DMF) is a drug that is orally administered for the treatment of relapsing-remitting multiple sclerosis. However, DMF causes gastrointestinal side effects and flushing in 43 % of patients, which significantly contributes to treatment discontinuation. To reduce side effects and increase patient compliance, the aim of this study was to develop a thermosensitive chitosan/glycerophosphate hydrogel for the nasal administration of DMF. A binary system of DMF with hydroxypropyl-β-cyclodextrin (HP-β-CD) was made and included in the hydrogel precursor solution. The precursor solution (drug content, DMF stability, thermogelling properties, viscosity), and the resulting thermosensitive hydrogel (mucoadhesion, in vitro DMF permeation) were characterized. HP-β-CD was able to interact with DMF and improve its water solubility. The leader thermosensitive nasal solution, G1 solution, was loaded with approximately 92 % DMF, which remained stable for 21 days. The G1 solution formed a hydrogel in approximately 2-1 min; it had a pH of 6.8 ± 0.06 and caused no significant change in the osmolality of the simulated nasal medium. The G1 hydrogel showed good mucoadhesive properties and released DMF that permeated in vitro in a controlled manner. As a result, G1 is a potential new approach to exploit the intranasal administration of DMF for treating multiple sclerosis.

Development and Characterization of Oral Raft Forming In Situ Gelling System of Neratinib Anticancer Drug Using 32 Factorial Design

Neratinib (NTB) is an irreversible inhibitor of pan-human epidermal growth factor receptor (HER-2) tyrosine kinase and is used in the treatment of breast cancer. It is a poorly aqueous soluble drug and exhibits extremely low oral bioavailability at higher pH, leading to a diminishing of the therapeutic effects in the GIT. The main objective of the research was to formulate an oral raft-forming in situ gelling system of NTB to improve gastric retention and drug release in a controlled manner and remain floating in the stomach for a prolonged time. In this study, NTB solubility was enhanced by polyethylene glycol (PEG)-based solid dispersions (SDs), and an in situ gelling system was developed and optimized by a two-factor at three-level (3²) factorial design. It was analyzed to study the impact of two independent variables viz sodium alginate [A] and HPMC K4M [B] on the responses, such as floating lag time, percentage (%) water uptake at 2 h, and % drug release at 6 h and 12 h. Among various SDs prepared using PEG 6000, formulation 1:3 showed the highest drug solubility. FT-IR spectra revealed no interactions between the drug and the polymer. The percentage of drug content in NTB SDs ranged from 96.22 ± 1.67% to 97.70 ± 1.89%. The developed in situ gel formulations exhibited a pH value of approximately 7. An in vitro gelation study of the in situ gel formulation showed immediate gelation and was retained for a longer period. From the obtained results of 3² factorial designs, it was observed that all the selected factors had a significant effect on the chosen response, supporting the precision of design employed for optimization. Thus, the developed oral raft-forming in situ gelling system of NTB can be a promising and alternate approach to enhance retention in the stomach and to attain sustained release of drug by floating, thereby augmenting the therapeutic efficacy of NTB.

Paclitaxel

Paclitaxel is the first microtubule-stabilizing agent identified and considered to be the most significant advance in chemotherapy of the past two decades. It is considered one of the most widely used antineoplastic agents with broad activity in several cancers including breast cancer, endometrial cancer, non-small-cell lung cancer, bladder cancer, and cervical carcinoma. It is also used for treating AIDS-related Kaposi sarcoma as a second line treatment. This comprehensive profile of paclitaxel gives overview of nomenclature, formulae, elemental analysis, appearance, application and uses. In addition, mechanism of action and resistance, different dosage forms and methods of drug preparation are elaborated. Moreover, the physicochemical properties involving X-ray powder diffraction pattern, drug solubility, melting point, differential scanning calorimetry, and stability were summarized. Furthermore, method of drug analysis including compendial, spectrophotometric, and chromatographic was discussed.

Development of thermosensitive chitosan/glicerophospate injectable in situ gelling solutions for potential application in intraoperative fluorescence imaging and local therapy of hepatocellular carcinoma: a preliminary study

OBJECTIVES

Thermosensitive chitosan/glycerophosphate (C/GP) solutions exhibiting sol-gel transition around body temperature were prepared to develop a class of injectable hydrogel platforms for the imaging and loco-regional treatment of hepatocellular carcinoma (HCC). Indocyanine green (ICG) was loaded in the thermosensitive solutions in order to assess their potential for the detection of tumor nodules by fluorescence.

METHODS

The gel formation of these formulations as well as their gelling time, injectability, compactness and resistance of gel structure, gelling temperature, storage conditions, biodegradability, and in vitro dye release behavior were investigated. Ex vivo studies were carried out for preliminary evaluation using an isolated bovine liver.

RESULTS

Gel strengths and gelation rates increased with the cross-link density between C and GP. These behaviors are more evident for C/GP solutions, which displayed a gel-like precipitation at 4°C. Furthermore, formulations with the lowest cross-link density between C and GP exhibited the best injectability due to a lower resistance to flow. The loading of the dye did not influence the gelation rate. ICG was not released from the hydrogels because of a strong electrostatic interaction between C and ICG. Ex vivo preliminary studies revealed that these injectable formulations remain in correspondence of the injected site.

CONCLUSIONS

The developed ICG-loaded hydrogels have the potential for intraoperative fluorescence imaging and local therapy of HCC as embolic agents. They form in situ compact gels and have a good potential for filling vessels and/or body cavities.

Gelucire based in situ gelling emulsions: a potential carrier for sustained stomach specific delivery of gastric irritant drugs

Non steroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed medications to the geriatric patients for the treatment of arthritis and other painful disorders. The major side effects of NSAIDs are related to their effects on the stomach and bowels. The present study concerns assessment of the potential of liquid in situ gelling emulsion formulations (emulgels) as patient compliant stomach specific sustained release carrier for the delivery of highly gastric irritant drug, Piroxicam. Emulgels were prepared, without using any emulgent, by mixing different concentrations of molten Gelucire 39/01 with low viscosity sodium alginate solution prepared in deionized water at 50°C. CaCO₃ was used as buoyancy imparting as well as crosslinking agent. Emulgels so prepared were homogenous, physically stable, and rapidly formed into buoyant gelled mass when exposed to simulated gastric fluid (SGF, pH 1.2). Drug release studies carried out in SGF revealed significant retardation (P < 0.05) of Piroxicam release from emulgels compared to conventional in situ gelling formulations prepared without Gelucire 39/01. Pharmacodynamic studies carried out in albino rats revealed significantly increased analgesic/anti-inflammatory response from in situ emulgels compared to conventional in situ gelling formulations. Further, in vivo toxicity studies carried out in albino rats revealed no signs of gastric ulceration upon prolonged dosing.

Pharmaceutical applications of the Calu-3 lung epithelia cell line

INTRODUCTION

The Calu-3 lung cell line has been shown to be a promising in vitro model of airway epithelia due to its similarity to in vivo physiology. Hence, over the past decade, it has found increasing applications in the pharmaceutical industry.

AREAS COVERED

This review focuses on the pharmaceutical applications of the Calu-3 cell line in areas such as mechanisms of drug transport, studying aerosol deposition, controlled release studies and identification of possible drug-drug interactions. The main findings of various studies, as well as the predictive potential of this model, are presented and discussed in this review.

EXPERT OPINION

There is still a lack of mechanistic knowledge regarding transport of inhaled therapeutics across the lungs. Cell culture models such as Calu-3 provide a simple and reproducible system to study the underlying mechanisms by which inhaled therapeutics interact with the lungs. However, more complex systems that integrate particle deposition onto different cell culture systems may be useful in addressing some fundamental questions to generate a better understanding of determinants that influences pulmonary drug dissolution, absorption, metabolism and efficacy. Ultimately the use of the Calu-3 cell line provides a basic research tool that enables the development of safer and more effective inhaled therapeutics.

Barrier characteristics of epithelial cultures modelling the airway and intestinal mucosa: a comparison

The barrier characteristics of polarized layers of Calu-3 and Caco-2 cell lines, as commonly used in vitro models of intestinal and airway mucosa, respectively, were investigated by assessing the translocation of model macromolecules and nanoparticles. The barrier capacity of the cell layers towards the movement of macromolecules and nanoparticulates differed considerably between the cell lines. Permeability studies revealed the existence of a notably larger solute molecular weight limit for paracellular diffusion in Caco-2 monolayers compared to Calu-3 cells. Removal of mucus in Calu-3 cells resulted in cell layers exhibiting a larger macromolecular permeability, in addition to improved nanoparticle translocation. Microscopic examination of the tight junctions, as cellular features that play a major role in preventing transepithelial movement of macromolecules, revealed that the appearance of cell-cell boundaries was notably different in the two cell lines, which could explain the differences in macromolecular permeability. The data overall showed that epithelial layers of airway Calu-3 and intestinal Caco-2 cell cultures in vitro exhibit a different level of restrictiveness and this is due to the cell morphology and the presence of mucus.

Antitumor efficacy, tumor distribution and blood pharmacokinetics of chitosan/glyceryl-monooleate nanostructures containing paclitaxel

AIMS

This investigation compared the tumor distribution, efficacy, blood pharmacokinetic parameters and hematological alterations following treatment with chitosan/glyceryl-monooleate (GMO) nanostructures containing paclitaxel (PTX) to a conventional formulation of PTX (Taxol(®)) in BALB/c female mice.

MATERIALS & METHODS

The tumor and blood concentrations of PTX were evaluated by HPLC and the pharmacokinetic parameters were determined through noncompartmental methods. Tumor development was evaluated by histopathological methods and hematological composition was monitored through differential white blood cells counts.

RESULTS

Lower localized or intravenous doses of PTX-chitosan/GMO nanostructures significantly increased the antitumor activity of paclitaxel. The tumor distribution studies showed effective concentrations in the tumors with the chitosan/GMO formulation while systemic blood levels remained lower than after administration of the conventional formulation.

CONCLUSION

Delivery systems consisting of chitosan/GMO and PTX are safe and effective administered locally (intratumorally) or intravenously.

High-throughput screening of PLGA thin films utilizing hydrophobic fluorescent dyes for hydrophobic drug compounds

Hydrophobic, antirestenotic drugs such as paclitaxel (PCTX) and rapamycin are often incorporated into thin film coatings for local delivery using implantable medical devices and polymers such as drug-eluting stents and balloons. Selecting the optimum coating formulation through screening the release profile of these drugs in thin films is time consuming and labor intensive. We describe here a high-throughput assay utilizing three model hydrophobic fluorescent compounds: fluorescein diacetate (FDAc), coumarin-6, and rhodamine 6G that were incorporated into poly(d,l-lactide-co-glycolide) (PLGA) and PLGA-polyethylene glycol films. Raman microscopy determined the hydrophobic fluorescent dye distribution within the PLGA thin films in comparison with that of PCTX. Their subsequent release was screened in a high-throughput assay and directly compared with HPLC quantification of PCTX release. It was observed that PCTX controlled-release kinetics could be mimicked by a hydrophobic dye that had similar octanol-water partition coefficient values and homogeneous dissolution in a PLGA matrix as the drug. In particular, FDAc was found to be the optimal hydrophobic dye at modeling the burst release as well as the total amount of PCTX released over a period of 30 days.

The effect of polyethylene glycol structure on paclitaxel drug release and mechanical properties of PLGA thin films

Thin films of poly(lactic acid-co-glycolic acid) (PLGA) incorporating paclitaxel typically have slow release rates of paclitaxel of the order of 1 μg day(-1) cm(-2). For implementation as medical devices a range of zero order release rates (i.e. 1-15 μg day(-1) cm(-2)) is desirable for different tissues and pathologies. Eight and 35 kDa molecular weight polyethylene glycol (PEG) was incorporated at 15%, 25% and 50% weight ratios into PLGA containing 10 wt.% paclitaxel. The mechanical properties were assessed for potential use as medical implants and the rates of release of paclitaxel were quantified as per cent release and the more clinically useful rate of release in μg day(-1) cm(-2). Paclitaxel quantitation was correlated with the release of PEG from PLGA, to further understand its role in paclitaxel/PLGA release modulation. PEG release was found to correlate with paclitaxel release and the level of crystallinity of the PEG in the PLGA film, as measured by Raman spectrometry. This supports the concept of using a phase separating, partitioning compound to increase the release rates of hydrophobic drugs such as paclitaxel from PLGA films, where paclitaxel is normally homogeneously distributed/dissolved. Two formulations are promising for medical device thin films, when optimized for tensile strength, elongation, and drug release. For slow rates of paclitaxel release an average of 3.8 μg day(-1) cm(-2) using 15% 35k PEG for >30 days was achieved, while a high rate of drug release of 12 μg day(-1) cm(-2) was maintained using 25% 8 kDa PEG for up to 12 days.

Chitosan and glyceryl monooleate nanostructures containing gemcitabine: potential delivery system for pancreatic cancer treatment

The objectives of this study are to enhance cellular accumulation of gemcitabine with chitosan/glyceryl monooleate (GMO) nanostructures, and to provide significant increase in cell death of human pancreatic cancer cells in vitro. The delivery system was prepared by a multiple emulsion solvent evaporation method. The nanostructure topography, size, and surface charge were determined by atomic force microscopy (AFM), and a zetameter. The cellular accumulation, cellular internalization and cytotoxicity of the nanostructures were evaluated by HPLC, confocal microscopy, or MTT assay in Mia PaCa-2 and BxPC-3 cells. The average particle diameter for 2% and 4% (w/w) drug loaded delivery system were 382.3 +/- 28.6 nm, and 385.2 +/- 16.1 nm, respectively with a surface charge of +21.94 +/- 4.37 and +21.23 +/- 1.46 mV. The MTT cytotoxicity dose-response studies revealed the placebo at/or below 1 mg/ml has no effect on MIA PaCa-2 or BxPC-3 cells. The delivery system demonstrated a significant decrease in the IC50 (3 to 4 log unit shift) in cell survival for gemcitabine nanostructures at 72 and 96 h post-treatment when compared with a solution of gemcitabine alone. The nanostructure reported here can be resuspended in an aqueous medium that demonstrate increased effective treatment compared with gemcitabine treatment alone in an in vitro model of human pancreatic cancer. The drug delivery system demonstrates capability to entrap both hydrophilic and hydrophobic compounds to potentially provide an effective treatment option in human pancreatic cancer.

Dual drug loaded superparamagnetic iron oxide nanoparticles for targeted cancer therapy

The primary inadequacy of chemotherapeutic drugs is their relative non-specificity and potential side effects to the healthy tissues. To overcome this, drug loaded multifunctional magnetic nanoparticles are conceptualized. We report here an aqueous based formulation of glycerol monooleate coated magnetic nanoparticles (GMO-MNPs) devoid of any surfactant capable of carrying high payload hydrophobic anticancer drugs. The biocompatibility was confirmed by tumor necrosis factor alpha assay, confocal microscopy. High entrapment efficiency approximately 95% and sustained release of encapsulated drugs for more than two weeks under in vitro conditions was achieved for different anticancer drugs (paclitaxel, rapamycin, alone or combination). Drug loaded GMO-MNPs did not affect the magnetization properties of the iron oxide core as confirmed by magnetization study. Additionally the MNPs were functionalized with carboxylic groups by coating with DMSA (Dimercaptosuccinic acid) for the supplementary conjugation of amines. For targeted therapy, HER2 antibody was conjugated to GMO-MNPs and showed enhanced uptake in human breast carcinoma cell line (MCF-7). The IC(50) doses revealed potential antiproliferative effect in MCF-7. Therefore, antibody conjugated GMO-MNPs could be used as potential drug carrier for the active therapeutic aspects in cancer therapy.

Chitosan-based hydrogels for controlled, localized drug delivery

Hydrogels are high-water content materials prepared from cross-linked polymers that are able to provide sustained, local delivery of a variety of therapeutic agents. Use of the natural polymer, chitosan, as the scaffold material in hydrogels has been highly pursued thanks to the polymer's biocompatibility, low toxicity, and biodegradability. The advanced development of chitosan hydrogels has led to new drug delivery systems that release their payloads under varying environmental stimuli. In addition, thermosensitive hydrogel variants have been developed to form a chitosan hydrogel in situ, precluding the need for surgical implantation. The development of these intelligent drug delivery devices requires a foundation in the chemical and physical characteristics of chitosan-based hydrogels, as well as the therapeutics to be delivered. In this review, we investigate the newest developments in chitosan hydrogel preparation and define the design parameters in the development of physically and chemically cross-linked hydrogels.

US-guided interstitial chemotherapy using paclitaxel temperature-responsive gel for breast cancer treatment in rat

INTRODUCTION

This study aims to investigate the therapeutic effect of paclitaxel temperature-responsive gel (PTRG) for interstitial chemotherapy on breast cancer, and to explore a new minimally invasive treatment for breast cancer.

MATERIALS AND METHODS

Breast cancer models were induced in rats using subcutaneous transplantation of tumor cells. The rats were then divided into control, paclitaxel injection, gel injection and paclitaxel-gel (PG) group. Following treatment, all animals were checked regularly by ultrasonography to observe changes in the tumors. Biopsy tumor tissues were processed for histopathological examination, and apoptotic index was determined by the terminal deoxynucleotidyl transferase dUTP nick end labeling method. In addition, blood cell count and liver transaminase activity were monitored, and the survival time of rats with cancer recorded.

RESULTS

Rats in PG group exhibited liquefaction necrosis of tumors. Ninety days after the experiment, four rats exhibited complete extinction of tumors, indicating full recovery. Pathological examination revealed that the tumor tissues in these rats were mostly necrotic, and the apoptotic index of tumor cells increased markedly compared to PI group. Also, the red blood cell, hemoglobin and white blood cell levels declined significantly in the PI group compared with PG group, while glutamic-pyruvic transaminase and glutamic-oxalacetic transaminase activities significantly increased. Meanwhile, no toxicity due to treatment was observed in PG group.

CONCLUSION

Interstitial chemotherapy mediated by PTRG appeared to be a safe and effective treatment for breast cancer in rats. It might have clinical applications for treating human breast cancer.

A novel nanoparticle formulation for sustained paclitaxel delivery

PURPOSE

To develop a novel nanoparticle drug delivery system consisting of chitosan and glyceryl monooleate (GMO) for the delivery of a wide variety of therapeutics including paclitaxel.

METHODS

Chitosan/GMO nanoparticles were prepared by multiple emulsion (o/w/o) solvent evaporation methods. Particle size and surface charge were determined. The morphological characteristics and cellular adhesion were evaluated with surface or transmission electron microscopy methods. The drug loading, encapsulation efficiency, in vitro release and cellular uptake were determined using HPLC methods. The safety and efficacy were evaluated by MTT cytotoxicity assay in human breast cancer cells (MDA-MB-231).

RESULTS

These studies provide conceptual proof that chitosan/GMO can form polycationic nano-sized particles (400 to 700 nm). The formulation demonstrates high yields (98 to 100%) and similar entrapment efficiencies. The lyophilized powder can be stored and easily be resuspended in an aqueous matrix. The nanoparticles have a hydrophobic inner-core with a hydrophilic coating that exhibits a significant positive charge and sustained release characteristics. This novel nanoparticle formulation shows evidence of mucoadhesive properties; a fourfold increased cellular uptake and a 1000-fold reduction in the IC(50) of PTX.

CONCLUSION

These advantages allow lower doses of PTX to achieve a therapeutic effect, thus presumably minimizing the adverse side effects.