Intestinal permeability of oxytetracycline from chitosan-montmorillonite nanocomposites

Formulation and evaluation of taste-masked oral disintegrating tablet containing tolterodine-loaded montmorillonite

Background and purpose

The present study aimed to obtain a taste-masked oral disintegrating tablet (ODT) containing tolterodine tartrate (TT) intercalated into montmorillonite (MMT).

Experimental approach

The TT-MMT hybrid was prepared by ion exchange reaction. The effect of the initial concentration of TT, MMT, temperature, and pH on the encapsulation efficiency (EE) % of the drug in MMT was evaluated. The selected TT-MMT hybrid was characterized by X-ray diffraction (XRD), Fourier transforms infrared (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Then, the optimized TT-MMT hybrid was incorporated in the ODT prepared by direct compression method and taste-masking assessment performed by a human test panel.

Findings/Results

The EE% of TT was in the range of 22.67 to 71.06% in different formulations. It was found that increases in MMT concentration significantly increased EE%. DSC and XRD studies indicated that the TT was intercalated in the MMT interlayer space in an amorphous or molecular state. In-vitro release studies at pH 6.8 showed that the amount of the drug released from the TT-MMT hybrid was negligible for the first 3 min. The post-compression of ODT also showed satisfactory results in terms of friability, hardness, disintegration time, and taste.

Conclusion and implications

MMT-ODT could be a suitable vehicle for the taste masking of TT, with the potential for use in patients with swallowing problems.

Natural and Synthetic Clay Minerals in the Pharmaceutical and Biomedical Fields

Clay minerals are historically among the most used materials with a wide variety of applications. In pharmaceutical and biomedical fields, their healing properties have always been known and used in pelotherapy and therefore attractive for their potential. In recent decades, the research has therefore focused on the systematic investigation of these properties. This review aims to describe the most relevant and recent uses of clays in the pharmaceutical and biomedical field, especially for drug delivery and tissue engineering purposes. Clay minerals, which are biocompatible and non-toxic materials, can act as carriers for active ingredients while controlling their release and increasing their bioavailability. Moreover, the combination of clays and polymers is useful as it can improve the mechanical and thermal properties of polymers, as well as induce cell adhesion and proliferation. Different types of clays, both of natural (such as montmorillonite and halloysite) and synthetic origin (layered double hydroxides and zeolites), were considered in order to compare them and to assess their advantages and different uses.

Pentoxifylline/Chitosan Films on Wound Healing: In Vitro/In Vivo Evaluation

This study aimed to develop films of chitosan (CSF) associated with pentoxifylline (PTX) for healing cutaneous wounds. These films were prepared at two concentrations, F1 (2.0 mg/mL) and F2 (4.0 mg/mL), and the interactions between the materials, structural characteristics, in vitro release, and morphometric aspects of skin wounds in vivo were evaluated. The formation of the CSF film with acetic acid modifies the polymeric structure, and the PTX demonstrates interaction with the CSF, in a semi-crystalline structure, for all concentrations. The release for all films was proportional to the concentration, with two phases: a fast one of ≤2 h and a slow one of >2 h, releasing 82.72 and 88.46% of the drug after 72 h, being governed by the Fickian diffusion mechanism. The wounds of the mice demonstrate a reduction of up to 60% in the area on day 2 for F2 when compared to CSF, F1, and positive control, and this characteristic of faster healing speed for F2 continues until the ninth day with wound reduction of 85%, 82%, and 90% for CSF, F1, and F2, respectively. Therefore, the combination of CSF and PTX is effective in their formation and incorporation, demonstrating that a higher concentration of PTX accelerates skin-wound reduction.

Correlation between Elemental Composition/Mobility and Skin Cell Proliferation of Fibrous Nanoclay/Spring Water Hydrogels

Inorganic hydrogels formulated with spring waters and clay minerals are used to treat musculoskeletal disorders and skin affections. Their underlying mechanism of action for skin disorders is not clear, although it is usually ascribed to the chemical composition of the formulation. The aim of this study was to assess the composition and in vitro release of elements with potential wound healing effects from hydrogels prepared with two nanoclays and natural spring water. In vitro Franz cell studies were used and the element concentration was measured by inductively coupled plasma techniques. Biocompatibility studies were used to evaluate the potential toxicity of the formulation against fibroblasts. The studied hydrogels released elements with known therapeutic interest in wound healing. The released ratios of some elements, such as Mg:Ca or Zn:Ca, played a significant role in the final therapeutic activity of the formulation. In particular, the proliferative activity of fibroblasts was ascribed to the release of Mn and the Zn:Ca ratio. Moreover, the importance of formulative studies is highlighted, since it is the optimal combination of the correct ingredients that makes a formulation effective.

Hybrid Systems Based on Talc and Chitosan for Controlled Drug Release

Inorganic matrices and biopolymers have been widely used in pharmaceutical fields. They show properties such as biocompatibility, incorporation capacity, and controlled drug release, which can become more attractive if they are combined to form hybrid materials. This work proposes the synthesis of new drug delivery systems (DDS) based on magnesium phyllosilicate (Talc) obtained by the sol–gel route method, the biopolymer chitosan (Ch), and the inorganic-organic hybrid formed between this matrix (Talc + Ch), obtained using glutaraldehyde as a crosslink agent, and to study their incorporation/release capacity of amiloride as a model drug. The systems were characterized by X-ray diffraction (XRD), Therma analysis TG/DTG, and Fourier-transform infrared spectroscopy (FTIR) that supported the DDS’s formation. The hybrid showed a better drug incorporation capacity compared to the precursors, with a loading of 55.74, 49.53, and 4.71 mg g⁻¹ for Talc + Ch, Talc, and Ch, respectively. The release assays were performed on a Hanson Research SR-8 Plus dissolver using apparatus I (basket), set to guarantee the sink conditions. The in vitro release tests showed a prolongation of the release rates of this drug for at least 4 h. This result proposes that the systems implies the slow and gradual release of the active substance, favoring the maintenance of the plasma concentration within a therapeutic window.

Bionanocomposites based on chitosan intercalation in designed swelling high-charged micas

Bionanocomposites based on layered inorganic components, as clays, and polymers of biological origin, as chitosan, have a major impact in medical and environmental fields, being economical and environmentally friendly materials. Na-Mn micas (n = 2 and 4) with controlled surface charge, high cation exchange capacity and swelling behaviour, are attractive inorganic composite components that exhibit improved adsorption properties compared to other inorganic solids which makes them potentially useful for bionanocomposites. The goal of this research was to explore the potential use of those synthetic brittle micas to form eco-friendly bionanocomposites with chitosan biopolymer. Hence, chitosan-mica bionanocomposites were prepared by ion-exchange reaction between chitosan solution and synthetic high charge mica. X-ray diffraction, Fourier transform infrared spectroscopy, thermal analysis, MAS-NMR spectroscopy and zeta-potential have been employed for bionanocomposites characterization. The results showed that the adsorption of chitosan is effective, although a chitosan portion remains in the outer surface being hydrogen-bonded to the tetrahedral sheet of the silicate.

Halloysite nanotubes as tools to improve the actual challenge of fixed doses combinations in tuberculosis treatment

Halloysite nanotubes (HLNTs) were used as nanocarriers of the tuberculostatic agent isoniazid (INH), a BCS (Biopharmaceutics Classification System) class III drug. Self-assembling nanohybrids (INH-loaded HLNTs) with an average outer diameter of 90 nm and polydispersity index of 0.7 approximately, were obtained by spontaneous adsorption of INH molecules to HLNTs powder in aqueous medium. The nanohybrids were aimed to improve oral drug bioavailability and reduce physicochemical incompatibility of INH with other concomitantly administered tuberculostatic agents. In vitro drug release from INH-loaded HLNTs was successfully fitted to a diffusive kinetic law founded on the adsorption-desorption equilibrium between drug molecules in solution and solid inorganic excipients. INH-loaded HLNTs showed good in vitro biocompatibility toward Caco-2 cells at the concentrations studied (up to 1233 μg/mL), with improved cell proliferation. Permeability tests showed that INH transport across Caco-2 cellular membranes was greatly enhanced and fluorescent microscopy confirmed that the drug encapsulated into nanohybrid was effectively internalized by the cells. INH-loaded HLNTs enhanced stability of the drug in presence of other tuberculostatic agents, both in binary and quaternary combinations. It has been demonstrated that simple interaction between INH with HLNTs leads to drug permeability and stability improvements that could greatly facilitate the design of multiple drug dosage forms, an actual challenge in oral treatment of tuberculosis. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2019.

Chitosan/beidellite nanocomposite as diclofenac carrier

Chitosan (CS) and purified sodium beidellite (Na-Bd) were used to obtain a nanocomposite able to carry anionic pharmaceutical ingredients. Diclofenac sodium (DS) was chosen as a model drug and was loaded by intercalation solution technique. Solid state characterization of the resultant hybrids was performed, including X-ray diffraction, Fourier transformed infrared spectroscopy, Thermal analysis and high resolution transmission electron microscopy coupled with energy dispersive X-Ray analysis. Drug loading capacity and encapsulation efficiency were quantified by measuring equilibrium concentration by UV-Vis spectroscopy at 276 nm. Solid-state characterization of the samples confirmed both chemical and physical interaction of DS with the nanocomposites. High drug loading along with a modified cumulative release of the drug in simulated intestinal fluid was obtained. The developed clay/polymer hybrids can act as potential candidates for the design of modified dosage forms of anionic drugs.

Facile Preparation of Biocomposite from Prawn Shell Derived Chitosan and Kaolinite-Rich Locally Available Clay

A novel composite material was prepared from prawn shell derived chitosan (CHT) and locally available kaolinite-rich modified Bijoypur clay (MC) using a facile technique in which dilute acetic acid was used as a solvent for dissolving chitosan and composite fabrication whereas distilled water was used for preparing the clay dispersion. Bijoypur clay mainly consists of kaolinite clay mineral and it was modified with the dodecyl amine to make it organophilic. Morphology and properties of the composites (different weight ratio of MC and CHT) have been studied and compared with those of pure CHT and MC. Purification and modification of Bijoypur clay were investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier transformed infrared spectroscopy (FTIR) analyses. The fabrication of CHT-MC composites was confirmed by FTIR analysis. Thermogravimetric analysis (TGA) and differential scanning colorimetry (DSC) were used to investigate the thermal stability of the composites. It was observed that dispersed clay improves the thermal stability and enhances the hardness of the matrix systematically with the increase of clay loading. In this study, a better insolubility in both acidic and alkaline media of the composites is also observed compared to pure chitosan.

Chitosan nanocomposites based on distinct inorganic fillers for biomedical applications

Chitosan (CHI), a biocompatible and biodegradable polysaccharide with the ability to provide a non-protein matrix for tissue growth, is considered to be an ideal material in the biomedical field. However, the lack of good mechanical properties limits its applications. In order to overcome this drawback, CHI has been combined with different polymers and fillers, leading to a variety of chitosan-based nanocomposites. The extensive research on CHI nanocomposites as well as their main biomedical applications are reviewed in this paper. An overview of the different fillers and assembly techniques available to produce CHI nanocomposites is presented. Finally, the properties of such nanocomposites are discussed with particular focus on bone regeneration, drug delivery, wound healing and biosensing applications.

Development of noncytotoxic chitosan-gold nanocomposites as efficient antibacterial materials

This work describes the synthesis and characterization of noncytotoxic nanocomposites either colloidal or as films exhibiting high antibacterial activity. The biocompatible and biodegradable polymer chitosan was used as reducing and stabilizing agent for the synthesis of gold nanoparticles embedded in it. Herein, for the first time, three different chitosan grades varying in the average molecular weight and deacetylation degree (DD) were used with an optimized gold precursor concentration. Several factors were analyzed in order to obtain antimicrobial but not cytotoxic nanocomposite materials. Films based on chitosan with medium molecular weight and the highest DD exhibited the highest antibacterial activity against biofilm forming strains of Staphylococcus aureus and Pseudomonas aeruginosa. The resulting nanocomposites did not show any cytotoxicity against mammalian somatic and tumoral cells. They produced a disruptive effect on the bacteria wall while their internalization was hindered on the eukaryotic cells. This selectivity and safety make them potentially applicable as antimicrobial coatings in the biomedical field.

Promethazine-montmorillonite inclusion complex to enhance drug photostability

The capability of montmorillonite as a matrix (MONT) to improve the photostability of photolabile drugs has been recently reported. Herein promethazine (PRO), which was chosen as a model drug because of its photodegradation mechanism, was intercalated into this inorganic matrix, and the effects on drug photoprotection were evaluated as well. The hybrid material (MONT-PRO) was successfully prepared with high drug loading and then was characterized by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and FTIR spectroscopy. The spectrophotometric measurements as a function of light exposure time showed that PRO intercalation into montmorillonite markedly improved the drug photostability because a 5-fold-slower degradation rate was determined compared to that measured for PRO in homogeneous solutions; nanosecond transient absorption measurements highlighted that the interaction with the inorganic matrix made negligible the photoionization process of the drug, and its efficiency in producing singlet oxygen was strongly reduced. The MONT-PRO intercalation compound could be easily formulated in gel or ointment media without losing its photostability.