Elucidation of release characteristics of highly soluble drug trimetazidine hydrochloride from chitosan-carrageenan matrix tablets

Polyelectrolytes for Environmental, Agricultural, and Medical Applications

In recent decades, polyelectrolytes (PELs) have attracted significant interest owing to a surge in research dedicated to the development of new technologies and applications at the biological level. Polyelectrolytes are macromolecules of which a substantial portion of the constituent units contains ionizable or ionic groups. These macromolecules demonstrate varied behaviors across different pH ranges, ionic strengths, and concentrations, making them fascinating subjects within the scientific community. The aim of this review is to present a comprehensive survey of the progress in the application studies of polyelectrolytes and their derivatives in various fields that are vital for the advancement, conservation, and technological progress of the planet, including agriculture, environmental science, and medicine. Through this bibliographic review, we seek to highlight the significance of these materials and their extensive range of applications in modern times.

Algal Phycocolloids: Bioactivities and Pharmaceutical Applications

Seaweeds are abundant sources of diverse bioactive compounds with various properties and mechanisms of action. These compounds offer protective effects, high nutritional value, and numerous health benefits. Seaweeds are versatile natural sources of metabolites applicable in the production of healthy food, pharmaceuticals, cosmetics, and fertilizers. Their biological compounds make them promising sources for biotechnological applications. In nature, hydrocolloids are substances which form a gel in the presence of water. They are employed as gelling agents in food, coatings and dressings in pharmaceuticals, stabilizers in biotechnology, and ingredients in cosmetics. Seaweed hydrocolloids are identified in carrageenan, alginate, and agar. Carrageenan has gained significant attention in pharmaceutical formulations and exhibits diverse pharmaceutical properties. Incorporating carrageenan and natural polymers such as chitosan, starch, cellulose, chitin, and alginate. It holds promise for creating biodegradable materials with biomedical applications. Alginate, a natural polysaccharide, is highly valued for wound dressings due to its unique characteristics, including low toxicity, biodegradability, hydrogel formation, prevention of bacterial infections, and maintenance of a moist environment. Agar is widely used in the biomedical field. This review focuses on analysing the therapeutic applications of carrageenan, alginate, and agar based on research highlighting their potential in developing innovative drug delivery systems using seaweed phycocolloids.

Alleviating the Influence of Circadian Rhythms and Drug Properties to the Release of Paliperidone Gel Matrix Tablets with Compression Coating Technology and Microenvironment Shaping

The influence of circadian rhythms is an important content in oral dosage form study which is shown as different pH conditions and gastrointestinal dynamics in the gastrointestinal tract. The purpose of this study was to alleviate the influence of circadian rhythms and drug properties to the release of gel matrix tablets in vitro and in vivo. In this study, the compression coating technology and microenvironment shaping were utilized to achieve the alleviation of the influence of circadian rhythms and drug properties. The compression coating technology was used to alleviate the influence of gastrointestinal dynamics, and microenvironment shaping was used to alleviate the interference of different pH condition variations. The self-made compression coating tablet could maintain a consistent release rate in different pH conditions and different dynamic environments in vitro for 24 h. In vivo, the pharmacokinetic parameters C_max and T_max were 3701.675 ng/mL and 24 h, respectively, and the release effect in vivo was similar to the paliperidone osmotic pump tablet with the ability to alleviate the influence of circadian rhythms. The correlation coefficient R² was 0.9914 for the self-made paliperidone compression coating tablet in vitro-in vivo correlation. The interference caused by circadian rhythms was alleviated so that the compression coating technology with microenvironment shaping could replace the osmotic pump technology with easier preparation process and cheaper costs in vitro and in vivo and achieve the effect of alleviating the interference of circadian rhythms.

Marine Polysaccharides in Tailor- Made Drug Delivery

Abstract:

Marine sources have attracted much interest as an emerging source of biomaterials in drug delivery applications. Amongst all other marine biopolymers, polysaccharides have been the mostly investigated class of biomaterials. The low cytotoxic behavior, in combination with the newly explored health benefits of marine polysaccharides has made it one of the prime research areas in the pharmaceutical and biomedical fields. In this review, we focused on all available marine polysaccharides, including their classification based on biological sources. The applications of several marine polysaccharides in recent years for tissue-specific novel drug delivery including gastrointestinal, brain tissue, transdermal, ocular, liver, and lung have also been discussed here. The abundant availability in nature, cost-effective extraction, and purification process along with a favorable biodegradable profile will encourage researchers to continue investigating marine polysaccharides for exploring newer applications in targeting specific delivery of therapeutics.

Carrageenan gel beads for echinochrome inclusion: Influence of structural features of carrageenan

Carrageenan (CRG) and carrageenan/chitosan (CH) gel beads (CRG/CH) were prepared as a release delivery system for echinochrome A (Ech). According to spectral data, the Ech was dispersed in the polymer matrix, interacted with CRG, was not oxidised, and remained stable after encapsulation in CRG beads. Carrageenan beads containing Ech were coated with CH by layering. The influence of the structural features of CRG on the formation of beads and the beads morphology, swelling behaviour, mucoadhesive properties and drug release were evaluated. The polysaccharide matrices with Ech showed different swelling characteristics depending on the pH of the medium and the structure of the CRG used. The slow drug release from polysaccharide matrixes was observed for κ- and κ/β-CRG beads, that contained 3,6-anhydro-α-d-galactopyranose units and had high molecular weight. The obtained results showed the prospects of using polysaccharide beads to include Ech.

Naturally Occurring Polyelectrolytes and Their Use for the Development of Complex-Based Mucoadhesive Drug Delivery Systems: An Overview

Biopolymers have several advantages for the development of drug delivery systems, since they are biocompatible, biodegradable and easy to obtain from renewable resources. However, their most notable advantage may be their ability to adhere to biological tissues. Many of these biopolymers have ionized forms, known as polyelectrolytes. When combined, polyelectrolytes with opposite charges spontaneously form polyelectrolyte complexes or multilayers, which have great functional versatility. Although only one natural polycation-chitosan has been widely explored until now, it has been combined with many natural polyanions such as pectin, alginate and xanthan gum, among others. These polyelectrolyte complexes have been used to develop multiple mucoadhesive dosage forms such as hydrogels, tablets, microparticles, and films, which have demonstrated extraordinary potential to administer drugs by the ocular, nasal, buccal, oral, and vaginal routes, improving both local and systemic treatments. The advantages observed for these formulations include the increased bioavailability or residence time of the formulation in the administration zone, and the avoidance of invasive administration routes, leading to greater therapeutic compliance.

Dynamic structure model of polyelectrolyte complex based controlled-release matrix tablets visualized by synchrotron radiation micro-computed tomography

Hydrophilic matrix tablets are the most commonly used dosage forms to fabricate oral controlled-release systems. It is highly desirable to design delivery system with novel mechanism to achieve sustained drug release through a simplified preparation process. The chitosan-anionic polymers based matrix tablets is assumed to produce self-assembly in the gastrointestinal tract, then transferring into film-coated tablets from original matrix type. But its dynamic behavior during dissolution process and the on-going internal microstructural changes during drug release were still in the dark. In this study, by using synchrotron radiation X-ray micro-tomography (SR-μCT) with phase contrast imaging, the micro-structure characteristics of chitosan-λ-carrageenan (CS-λ-CG) matrix based tablets during the dissolution were successfully elucidated for the first time. The qualitative and quantitative analyses of intensity distribution distinguished a hydrated CS-λ-CG layer from a solid core. Visualization based on 3D models provided quantitative details on the micro-structural characteristics of hydration dynamics. After CS-λ-CG matrix tablets were immersed in simulated gastric fluid (SGF) pH 1.2 medium for 0.5-2.0 h, the hydrated layer transformed into a gel layer and a solid swollen layer. The erosion front, swelling front, and solvent penetration front were also defined from the distinguishable micro-structures. More importantly, once the matrix tablet was transferred from SGF to the simulated intestinal fluid (SIF) pH 6.8 medium, a new layer with the enhanced strength and compactness in comparison to common gels was formed on the surface of tablets. The temporal and spatial variation of 3D models further provided direct evidence for this cross-linking behavior, the new layer was composed of CS-λ-CG polyelectrolyte complexes (PEC) which subsequently dominated release mechanisms. In summary, the phase contrast SR-μCT technique was utilized to investigate the hydration dynamics of CS-λ-CG matrix tablets which was supposed to provide a novel drug release mechanism. Based on the structure feature obtained from the high contrast image, different hydration region was distinguished and the cross-linked film was identified and visualized directly for the first time.

Preparation of Sustained Release Tablet with Minimized Usage of Glyceryl Behenate Using Post-Heating Method

The purpose of this study was to prepare sustained release (SR) matrix tablets using a direct compression incorporated with a post-heating process. Allopurinol was selected due to the water-soluble property and Compritol 888 ATO® (also known as glyceryl behenate) was used as an SR matrix-forming agent. The API, SR material, microcrystalline cellulose, and magnesium stearate (lubricant) were mixed and prepared into a tablet by a direct compression method. The compressed tablets were stored in a dry oven at four temperatures (60, 70, 80, and 90°C) and for three time periods (15, 30, 45 min). The DSC and PXRD data indicated that the crystallinity of the API was not altered by the post-heating method. However, SEM images demonstrated that Compritol 888 ATO® was melted by the post-heating method, and that the melted Compritol 888 ATO® could form a strong matrix. This strong matrix led to the significant sustained release behavior of hydrophilic APIs. As little as 3 mg of Compritol 888 ATO® (0.65% of total tablet weight), when heated at 80°C for 15 min, showed sustained release over 10 h. The post-heating method exerted a significant influence on lipid-based matrix tablets and allowed a reduction in the amount of material required for a water-soluble drug. This will also provide a valuable insight into lipid-based SR tablets and will allow their application to higher quality products and easier processing procedures.

Tunable and sustained-release characteristics of venlafaxine hydrochloride from chitosan-carbomer matrix tablets based on in situ formed polyelectrolyte complex film coating

The objective of this study is to design sustained-release tablets using matrix technology, which can well control the release of highly water-soluble drugs with good system robustness and simple preparation process. Taking venlafaxine hydrochloride (VH) as a drug model, the feasibility of using chitosan (CS), carbomer (CBM) combination system to achieve this goal was studied. Formulation and process variables influencing drug release from CS-CBM matrix tablets were investigated. It was found that CS-CBM combination system weakened the potential influence of CS, CBM material properties and gastric emptying time on drug release profile. Demonstrated by direct observation, differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), in situ self-assembled polyelectrolyte complex (PEC) film was formed on the tablet surface during gastrointestinal tract transition, which contributed to the tunable and robust control of drug release. The sustained drug release behavior was further demonstrated in vivo in Beagle dogs, with level A in vitro and in vivo correlation (IVIVC) established successfully. In conclusion, CS-CBM matrix tablets are promising system to tune and control the release of highly water-soluble drugs with good system robustness.

Review for carrageenan-based pharmaceutical biomaterials: favourable physical features versus adverse biological effects

Carrageenan (CRG) is a family of natural polysaccharides derived from seaweeds and has widely been used as food additives. In the past decade, owing to its attractive physicochemical properties, CRG has been developed into versatile biomaterials vehicles for drug delivery. Nevertheless, studies also emerged to reveal its adverse effects on the biological system. In this review, we critically appraise the latest literature (two thirds since 2008) on the development of CRG-based pharmaceutical vehicles and the perspective of using CRG for broader biomedical applications. We focus on how current strategies exploit the unique gelling mechanisms, strong water absorption and abundant functional groups of the three major CRG varieties. Notably, CRG-based matrices are demonstrated to increase drug loading and drug solubility, enabling release of orally administrated drugs in zero-order or in a significantly prolonged period. Other amazing features, such as pH-sensitivity and adhesive property, of CRG-based formulations are also introduced. Finally, we discuss the adverse influence of CRG on the human body and then suggest some future directions for the development of CRG-based biomaterials for broader applications in biomedicine.

Advances in oral controlled drug delivery: the role of drug-polymer and interpolymer non-covalent interactions

INTRODUCTION

After more than four decades of intense research, oral controlled drug delivery systems (DDSs) still represent a topic of major interest for pharmaceutical scientist and formulators. This can be explained in part by considering the economic value of oral DDSs whose market accounts for more than half of the overall drug delivery market. Polymeric systems based on drug-polymer non-covalent interaction represent a limited, but growing part of the field. Despite the large amount of literature and published reviews covering specific aspects, there is still need for a review of the relevant literature providing a general picture of the topic.

AREAS COVERED

The present review aims at presenting the latest findings in drug-polymer and interpolymer non-covalent interactions in oral controlled delivery while providing a specific perspective and a critical point of view, particularly on the tools and methods used for the study of these DDSs. Four main sections are considered: i) ionic interactions between drugs and polymers; ii) interpolymer complexes; iii) hydrogen bond; and iv) hydrophobic interactions.

EXPERT OPINION

The largest part of the scientific literature deals with systems based on drug-polymer ionic interactions while hydrogen bonding and hydrophobic interaction though, very promising, are more difficult to exploit, and therefore less studied. An accurate and exhaustive representation of the specific role of the chemical functions in establishing predictable interactions between drug and polymers is still required.

Industrial applications of marine carbohydrates

Biomaterials have been used increasingly in various fields, such as drug delivery, imaging, and tissue engineering. The main reason justifying the widespread use of biomaterials relies on its valuable and low-cost source of new drugs. Current research goals are focused on identifying more potent and specific compounds with antitumor, immunomodulatory, antihyperlipidemic, anticoagulant, and antiviral activities. The increasing knowledge of structural analysis and chemical modifications enables the use of these marine carbohydrates in a newer way for the human welfare. This chapter focuses on the recent developments related to industrial and biomedical applications using chitin, chitosan, alginate, agar, and carrageenan derivatives and reports the main advances published over the last 10-15 years.

Soluble chitosan-carrageenan polyelectrolyte complexes and their gastroprotective activity

The soluble polyelectrolyte complexes (PEC) κ-carrageenan (κ-CG):chitosan was obtained. Binding constant value (2.11 × 10(7)mol(-1)) showed high affinity of κ-CG to chitosan. The complex formation of κ-CG:chitosan 1:10 and 10:1 w/w was shown by centrifugation in a Percoll gradient. Using atomic force microscopy we showed that the supramolecular structure of the complexes is different from each other and from the macromolecular structure of the initial polysaccharides. The gastroprotective and anti-ulcerogenic effect of κ-CG, chitosan and their complexes was investigated on the model of stomach ulcers induced by indometacin in rats. PEC κ-CG:chitosan have gastroprotective properties which depend on their composition. Complex κ-CG:chitosan 1:10 w/w possesses higher gastroprotective activity than the complex 10:1 w/w. These results suggest that the gastroprotective effect of complexes can be associated with their protective layer on the surface of the mucous membrane of a stomach, which avoids a direct contact with the ulcerogenic agent.

An innovative matrix controlling drug delivery produced by thermal treatment of DC tablets containing polycarbophil and ethylcellulose

An innovative matrix, produced by thermal treatment on direct compression (DC) tablets containing polycarbophil (POL) and ethylcellulose (EC), identified as matrix forming polymers, and able to control the release of diltiazem hydrochloride, was developed. At pH 7.2, 72 ± 1.2% (w/w) of drug loaded was released in 25 h, mostly at constant rate. This swellable and unerodible matrix controls drug release by an anomalous transport mechanism. The modifications induced by the thermal treatment are irreversible and can be used to control and characterize the matrix. A 3-component constrained mixture design allowed the investigation of the experimental domain in which the matrix forms and the computation of a mathematical model that can be used to optimize the formulation properties. The release rate can be modulated (0.032-0.064% drug released/min) through the choice of suitable treatment conditions and tablet composition. The maximum amount of diltiazem hydrochloride released by zero-order kinetics, at the lowest release rate, occurs for POL:EC ratio in the range of 1:1-2:3 with 20-30% of diluent. The tablets are able to load up to 50% (w/w) of diltiazem hydrochloride without losing their properties. A stability study performed on a selected formulation containing DTZ showed stability for at least 2.7 years at RT conditions.