Role of excipients and polymeric advancements in preparation of floating drug delivery systems

Current trends in 3D printed gastroretentive floating drug delivery systems: A comprehensive review

Gastrointestinal (GI) environment is influenced by several factors (gender, genetics, sex, disease state, food) leading to oral drug absorption variability or to low bioavailability. In this scenario, gastroretentive drug delivery systems (GRDDS) have been developed in order to solve absorption problems, to lead to a more effective local therapy or to allow sustained drug release during a longer time period than the typical oral sustained release dosage forms. Among all GRDDS, floating systems seem to provide a promising and practical approach for achieving a long intra-gastric residence time and sustained release profile. In the last years, a novel technique is being used to manufacture this kind of systems: three-dimensional (3D) printing technology. This technique provides a versatile and easy process to manufacture personalized drug delivery systems. This work presents a systematic review of the main 3D printing based designs proposed up to date to manufacture floating systems. We have also summarized the most important parameters involved in buoyancy and sustained release of the systems, in order to facilitate the scale up of this technology to industrial level. Finally, a section discussing about the influence of materials in drug release, their biocompatibility and safety considerations have been included.

Polymeric Excipients in the Technology of Floating Drug Delivery Systems

The combination of targeted transport and improvement of the release profile of the active pharmaceutical ingredient (API) is a current trend in the development of oral medicinal products (MP). A well-known way to implement this concept is to obtain floating gastroretentive delivery systems that provide a long stay of the dosage form (DF) on the surface of the stomach contents. The nomenclature of excipients (Es) of a polymeric nature used in the technology of obtaining floating drug delivery systems (FDDS) is discussed. Based on the data presented in research papers, the most widely used groups of polymers, their properties, and their purpose in various technological approaches to achieving buoyancy have been determined. In addition, ways to modify the release of APIs in these systems and the Es used for this are described. The current trends in the use of polymers in the technology of floating dosage forms (FDF) and generalized conclusions about the prospects of this direction are outlined.

Ameliorated Stomach Specific Floating Microspheres for Emerging Health Pathologies Using Polymeric Konjac Glucomannan-Based Domperidone

The goal of this study was to use polymeric konjac glucomannan (KGM), Kollidon VA 64 (KVA64), and glutaraldehyde to ameliorate stomach specific floating microspheres (SSFM) using domperidone (DoN) to increase in vivo bioavailability and emerging health pathologies. The SSFM were made using the emulsion cross-linking process, and the polymer was chosen based on its ability to get cross-linked. The thermodynamic parameters were used to determine the AL classes of phase solubility curves using ideal complexes produced with KVA64. The optimal interaction constants at 25 and 37°C were found to be 116.14 and 128.05 M-1, respectively. The prepared SSFM had an average particle size (PS) of 163.71 ± 2.26 mm and a drug content of 96.66 ± 0.32%. It can be determined from in vitro drug release experiments that drug release is good in terms of regulated drug release after 12 h (92.62 ± 2.43%). The SSFMs were approximately sphere-shaped and had smooth surfaces, according to the morphological data. SSFMs were investigated using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and differential scanning calorimetry (DSC), and no chemical structural changes were identified. The SSFMs produces a considerable gastric residence time with optimal DoN release and absorption in stomach fluid, and the mean residence time (17.36 ± 1.4 h) and t 1/2 (10.47 ± 0.6 h) were considerably longer (p < 0.05) than those obtained following i.v. treatment (MRT = 8.42 ± 1.2 h; t 1/2 = 9.07 ± 0.7 h). The SSFMs maintained good physical stability for three months when stored at room temperature.

Microsphere: A Wander around Drug Delivery

Microspheres have free-flowing powder characteristics consisting of synthetic polymers and proteins with a particle size of 1-1000 μm. Microsphere improves bioavailability, stability and targets the drug to a selected site at a predetermined rate. Sorts of microspheres are bioadhesive, floating, radioactive, polymeric, and biodegradable microspheres. Therefore, the array of practices for the groundwork of microspheres offers a chance to regulate drug administration properties and develop the therapeutic efficacy of a given drug. The microsphere is spherical microparticles & is employed where predictable & consistent particle area is vital. The microspheres have the drug located centrally within the particle encased within the unique polymeric membrane. The present review highlights various sorts of microspheres, different methods of preparation, their applications, and various parameters to gauge their efficiency. Microspheres have received much attention not just for prolonged release but also for targeted medicine. A systematic review of one of the most promising drug delivery systems should be easier to read than the medical research articles, as they target a wider audience. The systematic reviews of the microparticles conclude that spherical microspheres & are accustomed to delivering the drug at the target site with specificity if modified and take care of the specified concentration at the location of interest without the untoward effects presented during a consistent therapy to help research and retrieval of health.

FDM 3D-Printed Sustained-Release Gastric-Floating Verapamil Hydrochloride Formulations with Cylinder, Capsule and Hemisphere Shapes, and Low Infill Percentage

The aim of this work was to design and fabricate fused deposition modeling (FDM) 3D-printed sustained-release gastric-floating formulations with different shapes (cylinder, capsule and hemisphere) and infill percentages (0% and 15%), and to investigate the influence of shape and infill percentage on the properties of the printed formulations. Drug-loaded filaments containing HPMC, Soluplus^® and verapamil hydrochloride were prepared via hot-melt extrusion (HME) and then used to print the following gastric-floating formulations: cylinder-15, capsule-0, capsule-15, hemisphere-0 and hemisphere-15. The morphology of the filaments and the printed formulations were observed by scanning electron microscopy (SEM). The physical state of the drugs in the filaments and the printed formulations were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The printed formulations were evaluated in vitro, including the weight variation, hardness, floating time, drug content and drug release. The results showed that the drug-loaded filament prepared was successful in printing the gastric floating formulations. Verapamil hydrochloride was proved thermally stable during HME and FDM, and in an amorphous state in the filament and the printed formulations. The shape and infill percentage of the printed formulations effected the hardness, floating time and in vitro drug release.

Effect of nanoemulsion-loaded hybrid biopolymeric hydrogel beads on the release kinetics, antioxidant potential and antibacterial activity of encapsulated curcumin

Nanoemulsion encapsulated in the hydrogel beads are important entrants for loading hydrophobic active ingredients for enhancing their bioavailability and biological activities relevant in the pharmaceutical, food and cosmetic industries. Herein, we report the formulation of curcumin-loaded nanoemulsion encapsulated in ionotropic hybrid hydrogel beads of alginate, chitosan, gelatin and polyethylene oxide for effective delivery of curcumin. The release behaviour in simulated gastric and intestinal fluids (SGF and SIF) at 37 °C showed faster release in SGF which could be explained on the basis of mesh size, the extent of hydration and the complexation of the curcumin with the Ca2+ ions present within the hydrogel network. The free radical scavenging and antibacterial activities of the released curcumin in SGF were significantly greater than in SIF. This study shows promises of such hybrid systems, ignored so far, for proper encapsulation, protection and delivery of curcumin for the development of functional foods and pharmaceutics. The high structural stability of these nanoemulsion carriers and their effective delivery of curcumin provide a novel and tailored formulation out of existing polymers with plethora of advantages for oral drug delivery. Moreover, this study opens new door for different possibilities to improve the physicochemical characteristics and delivery of bioactive molecules like curcumin.

Optimized copolymeric microstructured platforms for smart controlled delivery of an anticoagulant drug: Preparation, in vitro assessment and crossover study in healthy adult human volunteers

In the present study, novel micro-structured copolymeric carriers were developed based on the grafting technology where acrylamide was chemically crosslinked with different types of Eudragits® (NE30D, L100, RL30D, or RS30D) based on a 4¹*2¹ factorial design. The designed systems efficiently engulfed the anticoagulant drug dipyridamole (DIP), within their formed entangled mesh of crosslinked polymeric network. An optimized formulation, ECOP4 with a desirability-value of 0.706, (in which DIP is engulfed within a copolymeric network of acrylamide and Eudragit® RS30D) showed high engulfment capacity (97.13 ± 1.34%) and controlled DIP release over 8 h. FTIR studies revealed absence of interactions between DIP and the formed copolymer. ECOP4 was further inserted within an easily-administered safe raft forming system composed of a mixture of LM-pectin and gellan gum. A pharmacokinetic study was performed using human volunteers to determine DIP concentration in their plasma after administering the designed formulation using the high-performance liquid chromatography (HPLC) method. A crossover design was adopted comparing the designed formulation with Persantin® 25 mg tablets as a reference standard. Superior results were obtained for the optimized formulation regarding the measured pharmacokinetic parameters (AUC_0-24h, C_max, and T_max) with a 2.31 fold increase in relative bioavailability, which reveals the usefulness of the designed grafted dipyridamole formulation in site-specific delivery system.

A Technical Approach of Solubility Enhancement of Poorly Soluble Drugs: Liquisolid Technique

BACKGROUND

Solubility is one of the significant pre-formulation properties which regulate the desired concentration of drug in the systemic circulation. Most of the newly discovered chemical entities show poor solubility which consequently leads to poor bioavailability. To enhance the bioavailability of such type of drugs is a big challenge for pharmaceutical scientists. Liquisolid technology is a new and advanced technology used to transform the liquid medication into dry, free-flowing and easily compressible dosage form incorporation with the carrier and coating material.

OBJECTIVES

This review represents the technical perspective of Liquisolid technologies that overcome the demerits of classic formulation strategies and amend the bioavailability of the poorly soluble drug. This technique is also approaches the stability, hygroscopicity and agglomeration issue which are mainly occurring in other techniques for solubility enhancement.

CONCLUSION

Several technologies have been utilized to minimize the solubility problem but due to the complicated and expensive machinery fails to achieve the desired bioavailability of the poorly soluble drugs. Therefore, Liquisolid technology has been introduced as an innovative and promising technique that recovers the demerits of classic formulation strategies and also improves the bioavailability of the poorly soluble drug. This article exhibits the technical approach of the liquisolid system by improving the solubility as well as bioavailability of water-insoluble drugs.

Formulation development and in-vitro/ex-vivo evaluation for a polysaccharide-based colon targeted matrix tablet

OBJECTIVE

The objective of this study was to develop and optimize a microflora-triggered colon targeted sustained-release dosage form using gum ghatti (GG) and hydroxypropyl methylcellulose (HPMC K100).

METHODS

GG and HPMC K100 were used to prepare microflora triggered colon targeted sustained-release dosage form. For evaluation, two different tablets comprising metoprolol succinate and mesalamine as an active ingredient were used with the objective of developing a platform technology for various categories of drugs. The tablets were coated with Eudragit® L100 and Eudragit® S100 to provide enteric coating and evaluated for hardness, thickness, friability, weight variation, disintegration, and drug content. In vitro release studies for the prepared tablets were carried out mimicking the physiological transit time. Further, the effects of microflora were evaluated using rat cecal content.

RESULTS

The in vitro dissolution profile of coated matrix tablets showed that 86.03±0.43% of metoprolol succinate and 80.26±0.67% of mesalamine were released at the end of 12 h. The ex vivo dissolution profile of coated matrix tablets showed that 96.50±0.27% of metoprolol succinate and 92.58±0.39% of mesalamine were released at the end of 12 h in the presence of rat ceacal content. The developed formulation was stable when subjected to the standard ICH stability study conditions.

CONCLUSION

The result of this study showed that gum ghatti together with hydroxypropyl methylcellulose could be successfully used for the preparation of microflora triggered colon targeted matrix tablets.

Development of Porous Epoxy Micro-Beads Using Ammonium Bicarbonate through a Single Epoxy Droplet in Corn Oil

This paper explored the effects of ammonium bicarbonate and different ratios of epoxy to polyamide on the formation of porous epoxy micro-beads through a single epoxy droplet. A single drop of a mixture, consisting of epoxy, polyamide, and ammonium bicarbonate, was dropped into heated corn oil at a temperature of 100 °C. An epoxy droplet was formed due to the immiscibility of the epoxy mixture and corn oil. The ammonium bicarbonate within this droplet underwent a decomposition reaction, while the epoxy and polyamide underwent a curing reaction, to form porous epoxy micro-beads. The result showed that the higher ammonium bicarbonate content in the porous, epoxy micro-beads increased the decomposition rate up to 11.52 × 10⁻³ cm³/s. In addition, a higher total volume of gas was generated when a higher ammonium bicarbonate content was decomposed. This led to the formation of porous epoxy micro-beads with a smaller particle size, lower specific gravity, and better thermal stability. At an epoxy to polyamide ratio of 10:6, many smaller micro-beads, with particle sizes ranging from 201 to 400 μm, were obtained at an ammonium bicarbonate content of 10 phr. Moreover, the porous epoxy micro-beads with open pores were shown to have a low specific gravity of about 0.93 and high thermal stability at a high ammonium bicarbonate content. Based on the findings, it was concluded that porous epoxy micro-beads were successfully produced using a single epoxy droplet in heated corn oil, where their shape and particle size depended on the content of ammonium bicarbonate and the ratio of epoxy to polyamide used.

[Preparation and in vitro evaluation of fused deposition modeling 3D printed verapa-mil hydrochloride gastric floating formulations]

OBJECTIVE

To explore the feasibility of preparing gastric floating formulations by fused de-position modeling (FDM) 3D printing technology, to evaluate the in vitro properties of the prepared FDM 3D printed gastric floating formulations, and to compare the influence of different external shapes of the formulation with their in vitro properties.

METHODS

Verapamil hydrochloride and polyvinyl alcohol (PVA) were used as the model drug and the excipient, respectively. The capsule-shaped and hemisphere-shaped gastric floating formulations were then prepared by FDM 3D printing. The infill percentages were 15%, the layer heights were 0.2 mm, and the roof or floor thicknesses were 0.8 mm for both the 3D printed formulations, while the number of shells was 3 and 4 for capsule-shaped and hemisphere-shaped formulation, respectively. Scanning electron microscopy (SEM) was used to observe the morpho-logy of the surface and cross section of the formulations. Gravimetric method was adopted to measure the weights of the formulations. Texture analyzer was employed to evaluate the hardness of the formulations. High performance liquid chromatography method was used to determine the drug contents of the formulations. The in vitro floating and drug release behavior of the formulations were also characterized.

RESULTS

SEM showed that the appearance of the FDM 3D printed gastric floating formulations were both intact and free from defects with the filling structure which was consistent with the design. The weight variations of the two formulations were relatively low, indicating a high reproducibility of the 3D printing fabrication. Above 800.0 N of hardness was obtained in two mutually perpendicular directions for the two formulations. The drug contents of the two formulations approached to 100%, showing no drug loss during the 3D printing process. The two formulations floated in vitro without any lag time, and the in vitro floating time of the capsule-shaped and hemisphere-shaped formulation were (3.97±0.41) h and (4.48±0.21) h, respectively. The in vitro release of the two formulations was significantly slower than that of the commercially available immediate-release tablets.

CONCLUSION

The capsule-shaped and hemisphere-shaped verapamil hydrochloride gastric floating formulations were prepared by FDM 3D printing technology successfully. Only the floating time was found to be influenced by the external shape of the 3D printed formulations in this study.

A Review: Uses of Chitosan in Pharmaceutical Forms

Chitosan is a natural polysaccharide widespread in nature. It has many unique and attractive properties for the pharmaceutical field: it is biodegradable, safe, hypoallergenic, biocompatible with the body, free of toxicity, with proven anticholesterolemic, antibacterial, and antimycotic action. In this review we highlighted the physical, chemical, mechanical, mucoadhesive, etc. properties of chitosan to be taken into account when obtaining various pharmaceutical forms. The methods by which the pharmaceutical forms based on chitosan are obtained are very extensive, and in this study only the most common ones were presented.

Raft-forming gastro-retentive formulations based on Centella asiatica extract-solid dispersions for gastric ulcer treatment

Liquid raft-forming formulations comprising solid dispersions of glycoside-rich Centella asiatica extract and Eudragit® EPO (GR-SD) were developed to achieve prolonged delivery of the glycosides, asiaticoside (AS) and madecassoside (MS) in the stomach and thus increase the effectiveness of gastric ulcer treatment. Solid dispersions of GR extract and Eudragit® EPO (GR-SD, weight ratio 1:0.5) resulted in the highest solubility of AS (41.7 mg/mL) and MS (29.3 mg/mL) and completed dissolution of both glycosides occurred in SGF within 10 min. The optimized raft-forming formulation was composed of alginate (2%), HPMC K-100 (0.5%), GR-SD (1.2%), and calcium carbonate (0.5%) as a calcium source and carbon dioxide producer. The formulation provided sufficient raft strength (> 7.0 g), rapid floating behavior in SGF (~30 s), and sustained release of AS (more than 80%) and MS (85%) over 8 h. GR-SD-based formulations administered once daily to rats for two days at a dose of 10 mg AS/kg reduced the severity of gastric ulcer induced by indomethacin with a greater curative efficacy than those of unformulated GR extract and a standard antiulcer agent: lansoprazole (p < 0.05). These findings demonstrate that GR-SD-based raft-forming systems offer significant promise for improving the treatment of gastric ulcers induced by non-steroidal anti-inflammatory drugs.

Preparation and In vitro Evaluation of FDM 3D-Printed Ellipsoid-Shaped Gastric Floating Tablets with Low Infill Percentages

The aim of the study is to investigate the feasibility of fabricating FDM 3D-printed gastric floating tablets with low infill percentages and the effect of infill percentage on the properties of gastric floating tablets in vitro. Propranolol hydrochloride was selected as a model drug, and drug-loaded polyvinyl alcohol (PVA) filaments were produced by hot melt extrusion (HME). Ellipsoid-shaped gastric floating tablets with low infill percentage of 15% and 25% (namely E-15 and E-25) were then prepared respectively by feeding the extruded filaments to FDM 3D printer. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM) were employed to characterize the filaments and 3D-printed tablets, and a series of evaluations were performed to the 3D-printed tablets, including the weight variation, drug content, hardness, in vitro floating behavior, and drug release of the tablets. The SEM results showed that the drug-loaded filaments and 3D-printed tablets appeared intact without defects, and the printed tablets were composed of filaments deposited uniformly layer by layer. The model drug and the excipients were thermally stable under the process temperature of extruding and printing, with a small amount of drug crystals dispersing in the drug-loaded filaments and 3D-printed tablets. Both E-15 and E-25 could float on artificial gastric fluids without any lag time and released in a sustained manner. Compared with E-15, the E-25 presented less weight variation, higher tablet hardness, shorter floating time, and longer drug release time.

Polymer blends used to develop felodipine-loaded hollow microspheres for improved oral bioavailability

Felodipine (FD) has been widely used in anti-hypertensive treatment. However, it has extremely low aqueous solubility and poor bioavailability. To address these problems, FD hollow microspheres as multiple-unit dosage forms were synthesized by a solvent diffusion evaporation method. Particle size of the hollow microspheres, types of ethylcellulose (EC), amounts of EC, polyvinyl pyrrolidone (PVP) and FD were investigated based on an orthogonal experiment of three factors and three levels. In addition, the release kinetics in vitro and pharmacokinetics in beagle dogs of the optimized FD hollow microspheres was investigated and compared with Plendil (commercial FD sustained-release tablets) as a single-unit dosage form. Results showed that the optimal formulation was composed of EC_{10 cp}:PVP:FD (0.9:0.16:0.36, w/w). The FD hollow microspheres were globular with a hollow structure and have high drug loading (17.69±0.44%) and floating rate (93.82±4.05%) in simulated human gastric fluid after 24h. Pharmacokinetic data showed that FD hollow microspheres exhibited sustained-release behavior and significantly improved relative bioavailability of FD compared with the control. Pharmacodynamic study showed that the FD hollow microspheres could effectively lower blood pressure. Therefore, these findings demonstrated that the hollow microspheres were an effective sustained-release delivery system for FD.

Design of porous Eudragit® L beads for floating drug delivery by wax removal technique

The aim of this study was to design porous matrix beads for floating drug delivery using enteric polymer, Eudragit^® L and various amounts of waxes (0, 0.1, 0.5, 1, 2 and 3% w/w). In this study, wax containing cetyl alcohol and white petrolatum was utilized to produce pores using a wax removal technique. To prepare the beads, Eudragit^® L, metronidazole and wax were dissolved in acetone and then extruded into dichloromethane. The effect of the amount of wax on the floating and drug release behavior of the Eudragit^® L beads was determined. After the extruded product was immersed in dichloromethane, wax dissolved out from the formed beads, resulting in a porous structure. The prepared beads could float in simulated gastric fluid for more than 10 hours. Different amounts of wax had an effect on the drug release. We found that when the percentage of wax increased, the drug release was higher while the beads remained floating. The results suggest that Eudragit^® L beads could be used as a carrier for an intragastric floating drug delivery system.