Preparation and Evaluation of Diclofenac Sodium Tablet Coated with Polyelectrolyte Multilayer Film Using Hypromellose Acetate Succinate and Polymethacrylates for pH-Dependent, Modified Release Drug Delivery

Optimization of Multilayer Films Composed of Chitosan and Low-Methoxy Amidated Pectin as Multifunctional Biomaterials for Drug Delivery

Polyelectrolyte multilayers (PEMs) based on polyelectrolyte complex (PEC) structures are recognized as interesting materials for manufacturing functionalized coatings or drug delivery platforms. Difficulties in homogeneous PEC system development generated the idea of chitosan (CS)/low-methoxy amidated pectin (LM PC) multilayer film optimization with regard to the selected variables: the polymer ratio, PC type, and order of polymer mixing. Films were formulated by solvent casting method and then tested to characterize CS/LM PC PECs, using thermal analysis, Fourier transform infrared spectroscopy (FTIR), turbidity, and zeta potential measurements. The internal structure of the films was visualized by using scanning electron microscopy. Analysis of the mechanical and swelling properties enabled us to select the most promising formulations with high uniformity and mechanical strength. Films with confirmed multilayer architecture were indicated as a promising material for the multifunctional systems development for buccal drug delivery. They were also characterized by improved thermal stability as compared to the single polymers and their physical mixtures, most probably as a result of the CS–LM PC interactions. This also might indicate the potential protective effect on the active substances being incorporated in the PEC-based films.

The Potential of Polyelectrolyte Multilayer Films as Drug Delivery Materials

Polyelectrolyte multilayers (PEMs) represent a group of polyelectrolyte complex (PEC)–based materials widely investigated in the biomedical and pharmaceutical sciences. Despite the unflagging popularity of the aforementioned systems in tissue engineering, only a few updated scientific reports concerning PEM potential in drug administration can be found. In fact, PEM coatings are currently recognized as important tools for functionalizing implantable scaffolds; however, only a small amount of attention has been given to PEMs as drug delivery materials. Scientific reports on PEMs reveal two dominant reasons for the limited usability of multilayers in pharmaceutical technology: complex and expensive preparation techniques as well as high sensitivity of interacting polyelectrolytes to the varieties of internal and external factors. The aim of this work was to analyze the latest approaches, concerning the potential of PEMs in pharmacy, chemical technology, and (primarily) tissue engineering, with special attention given to possible polymer combinations, technological parameters, and physicochemical characteristics, such as hydrophilicity, adhesive and swelling properties, and internal/external structures of the systems formed. Careful recognition of the above factors is crucial in the development of PEM-based drug delivery materials.

Biopharmaceutical characterization of a novel sustained-release formulation of allopurinol with reduced nephrotoxicity

The present study was aimed to develop a novel sustained-release formulation for allopurinol (ALP/SR) with the use of a pH-sensitive polymer, hydroxypropyl methylcellulose acetate succinate, to reduce nephrotoxicity. ALP/SR was evaluated in terms of crystallinity, the dissolution profile, pharmacokinetic behavior, and nephrotoxicity in a rat model of nephropathy. Under acidic conditions (pH1.2), sustained release behavior was seen for ALP/SR, although both crystalline ALP and ALP/SR exhibited rapid dissolution at neutral condition. After multiple oral administrations of ALP samples (10 mg-ALP/kg) for 4 days in a rat model of nephropathy, ALP/SR led to a low and sustained plasma concentration of ALP, as evidenced by half the maximum concentration of ALP and a 2.5-fold increase in the half-life of ALP compared with crystalline ALP, possibly due to suppressed dissolution behavior under acidic conditions. Repeated-dosing of ALP/SR resulted in significant reductions in plasma creatinine and blood urea nitrogen levels by 73% and 69%, respectively, in comparison with crystalline ALP, suggesting the low nephrotoxic risk of ALP/SR. From these findings, a strategic SR formulation approach might be an efficacious dosage option for ALP to avoid severe nephrotoxicity in patients with nephropathy.

Vaginal Polyelectrolyte Layer-by-Layer Films Based on Chitosan Derivatives and Eudragit® S100 for pH Responsive Release of Tenofovir

Women are still at high risk of contracting the human immunodeficiency virus (HIV) virus due to the lack of protection methods under their control, especially in sub-Saharan countries. Polyelectrolyte multilayer smart vaginal films based on chitosan derivatives (chitosan lactate, chitosan tartate, and chitosan citrate) and Eudragit^® S100 were developed for the pH-sensitive release of Tenofovir. Films were characterized through texture analysis and scanning electron microscopy (SEM). Swelling and drug release studies were carried out in simulated vaginal fluid and a mixture of simulated vaginal and seminal fluids. Ex vivo mucoadhesion was evaluated in bovine vaginal mucosa. SEM micrographs revealed the formation of multilayer films. According to texture analysis, chitosan citrate was the most flexible compared to chitosan tartrate and lactate. The swelling studies showed a moderate water uptake (<300% in all cases), leading to the sustained release of Tenofovir in simulated vaginal fluid (up to 120 h), which was accelerated in the simulated fluid mixture (4–6 h). The films had high mucoadhesion in bovine vaginal mucosa. The multilayer films formed by a mixture of chitosan citrate and Eudragit^® S100 proved to be the most promising, with zero toxicity, excellent mechanical properties, moderate swelling (<100%), high mucoadhesion capacity, and Tenofovir release of 120 h and 4 h in vaginal fluid and the simulated fluid mixture respectively.

Polysaccharide Thin Solid Films for Analgesic Drug Delivery and Growth of Human Skin Cells

Chronic wounds not only lower the quality of patient's life significantly, but also present a huge financial burden for the healthcare systems around the world. Treatment of larger wounds often requires the use of more complex materials, which can ensure a successful renewal or replacement of damaged or destroyed tissues. Despite a range of advanced wound dressings that can facilitate wound healing, there are still no clinically used dressings for effective local pain management. Herein, alginate (ALG) and carboxymethyl cellulose (CMC), two of the most commonly used materials in the field of chronic wound care, and combination of ALG-CMC were used to create a model wound dressing system in the form of multi-layered thin solid films using the spin-assisted layer-by-layer (LBL) coating technique. The latter multi-layer system was used to incorporate and study the release kinetics of analgesic drugs such as diclofenac and lidocaine at physiological conditions. The wettability, morphology, physicochemical and surface properties of the coated films were evaluated using different surface sensitive analytical tools. The influence of in situ incorporated drug molecules on the surface properties (e.g., roughness) and on the proliferation of human skin cells (keratinocytes and skin fibroblasts) was further evaluated. The results obtained from this preliminary study should be considered as the basis for the development "real" wound dressing materials and for 3D bio-printing applications.