A novel concept in enteric coating: A double-coating system providing rapid drug release in the proximal small intestine

"Enhancing Oral Drug Absorption: Overcoming Physiological and Pharmaceutical Barriers for Improved Bioavailability"

The oral route stands out as the most commonly used method for drug administration, prized for its non-invasive nature, patient compliance, and easy administration. Several elements influence the absorption of oral medications, including their solubility, permeability across mucosal membranes, and stability within the gastrointestinal (GI) environment. Research has delved into comprehending physicochemical, biochemical, metabolic, and biological obstacles that impact the bioavailability of a drug. To improve oral drug absorption, several pharmaceutical technologies and delivery methods have been studied, including cyclodextrins, micelles, nanocarriers, and lipid-based carriers. This review examines both traditional and innovative drug delivery methods, as well as the physiological and pharmacological barriers influencing medication bioavailability when taken orally. Additionally, it describes the challenges and advancements in developing formulations suitable for oral use.

Tablet formulation with dual control concept for efficient colonic drug delivery

Aim of this study was to develop a tablet formulation for targeted colonic drug release by implementing two control mechanisms: A pH-sensitive coating layer based on Eudragit® FS 30 D to prevent drug release in the upper gastrointestinal tract, combined with a matrix based on plant-derived polysaccharide xyloglucan to inhibit drug release after coating removal in the small intestine and to allow microbiome triggered drug release in the colon. In vitro dissolution tests simulated the passage through the entire gastrointestinal tract with a four-stage protocol, including microbial xyloglucanase addition in physiologically relevant concentrations as microbiome surrogate to the colonic dissolution medium. Matrix erosion was monitored in parallel to drug release by measurement of reducing sugar equivalents resulting from xyloglucan hydrolysis. Limited drug release in gastric and small intestinal test stages and predominant release in the colonic stage was achieved. The xyloglucan matrix controlled drug release after dissolution of the enteric coating through the formation of a gummy polysaccharide layer at the tablet surface. Matrix degradation was dependent on enzyme concentration in the colonic medium and significantly accelerated drug release resulting in erosion-controlled release process. Drug release at physiologically relevant enzyme concentration was completed within the bounds of colonic transit time. The dual control concept was applicable to two drug substances with different solubility, providing similar release rates in colonic environment containing xyloglucanase. Drug solubility mechanistically affected release, with diffusion of caffeine, but not of 5-ASA, contributing to the overall release rate out of the matrix tablet.

3D printing of bioactive materials for drug delivery applications

INTRODUCTION

Three-dimensional (3D) printing, also known as additive manufacturing (AM), is a modern technique/technology, which makes it possible to construct 3D objects from computer-aided design (CAD) digital models. This technology can be used in the progress of drug delivery systems, where porosity has played important role in attaining an acceptable level of biocompatibility and biodegradability with improved therapeutic effects. 3D printing may also provide the user possibility to control the dosage of each ingredient in order to a specific purpose, and makes it probable to improve the formulation of drug delivery systems.

AREAS COVERED

This article covers the 3D printing technologies, bioactive materials including natural and synthetic polymers as well as some ceramics and minerals and their roles in drug delivery systems.

EXPERT OPINION

This technology is feasible to fabricate drug products by incorporating multiple drugs in different parts in such a mode that these drugs can release from the section at a predetermined rate. Furthermore, this 3D printing technology has the possible to transform personalized therapy to various age-groups by design flexibility and precise dosing. In recent years, the potential use of this technology can be realized in a clinical situation where patients will acquire individualized medicine as per their require.

Improved dissolution of an enteric polymer and its amorphous solid dispersions by polymer salt formation

Weakly acidic polymers, historically used as enteric coatings, are increasingly being employed in solubility-enhancing amorphous solid dispersion (ASD) formulations. However, there is a lack of fundamental understanding around how these carboxylic acid-containing polymers dissolve, in particular when molecularly mixed with a lipophilic drug, as in an ASD. Identification of critical factors dominating their dissolution is vital for rational design of new polymers with enhanced release properties to address contemporary ASD delivery challenges, notably achieving good release at higher drug loadings. Herein, after identification of polymer solubilization via ionization as the rate limiting step for dissolution, hydroxypropylmethyl cellulose phthalate (HP-50) was converted to a salt by neutralization of the phthalic acid groups with different bases. Surface normalized dissolution was performed to assess the dissolution rate improvement achieved by polymer pre-ionization via salt formation. Polymer salts showed ∼ 3-fold faster release than HP-50 at pH 6.8 (50 mM sodium phosphate buffer). Importantly, a polymer salt was able to maintain a rapid dissolution rate, irrespective of the buffer capacity of the medium, whereas the protonated polymer showed greatly diminished dissolution as medium buffer capacity decreased toward physiological gastrointestinal tract values. HP-50 and two polymer salts were formulated into ASDs with miconazole, a lipophilic and weakly basic antifungal drug, at a 20% drug loading. Rapid drug release rates were achieved with polymer salt ASDs, whereby drug release was 14 times faster than from the protonated HP-50 ASD. This study highlights the critical role of polymer ionization and buffer capacity in the dissolution of HP-50-based systems and how pre-ionization via polymer salt formation is a successful strategy for the design of new polymers for improved ASD performance.

Clinical translation of advanced colonic drug delivery technologies

Targeted drug delivery to the colon offers a myriad of benefits, including treatment of local diseases, direct access to unique therapeutic targets and the potential for increasing systemic drug bioavailability and efficacy. Although a range of traditional colonic delivery technologies are available, these systems exhibit inconsistent drug release due to physiological variability between and within individuals, which may be further exacerbated by underlying disease states. In recent years, significant translational and commercial advances have been made with the introduction of new technologies that incorporate independent multi-stimuli release mechanisms (pH and/or microbiota-dependent release). Harnessing these advanced technologies offers new possibilities for drug delivery via the colon, including the delivery of biopharmaceuticals, vaccines, nutrients, and microbiome therapeutics for the treatment of both local and systemic diseases. This review details the latest advances in colonic drug delivery, with an emphasis on emerging therapeutic opportunities and clinical technology translation.

A Novel Multilayer Natural Coating for Fed-State Gastric Protection

Several nutraceutical products require gastric protection against the hostile environment in the stomach. Currently marketed synthetic and semi-synthetic coatings suffer from major shortcomings such as poor gastric protection, slow-release response to pH change, and the use of artificial ingredients. The challenge of coating natural products is further exacerbated by the relatively high gastric pH in the fed state. In this work, a novel natural enteric coating is presented as a breakthrough alternative to current solutions. Two coating systems were devised: (i) a triple-layer coating that comprises a wax layer embedded between two alginate-based coatings, and (ii) a double-layer coating, where an overcoat of organic acids (fumaric or citric acid) is applied to an alginate-based coating. The multi-layer architecture did not impact the pH-responsive nature of the coating even when more biologically relevant Krebs bicarbonate buffer of lower buffer capacity was used. Interestingly, the gastric protection barrier of organic acid-based coating remained resistant at elevated gastric pH 2, 3, or 4 for 2 h. This is the first report of using an alginate-based coating to provide gastric protection against fed-state stomach conditions (pH 2–4). Being biodegradable, naturally occurring, and with no limit on daily intake, the reported novel coating provides a superior platform to current coating solutions for pharmaceutical and nutraceutical products.

Current Film Coating Designs for Colon-Targeted Oral Delivery

Colon-targeted oral delivery has recently attracted a substantial number of studies on both systemic and local treatments. Among approaches for colonic delivery, film coatings have been demonstrated as effective elements of the drug delivery systems because they can integrate multiple release strategies, such as pH-controlled release, time-controlled release and enzyme-triggered release. Moreover, coating layer modulations, natural film materials and nanoparticle coatings have been vigorously investigated with promising applications. This review aims to describe the primary approaches for improving drug delivery to the colon in the last decade. The outstanding importance of current developments in film coatings will advance dosage form designs and lead to the development of efficient colon-targeted oral delivery systems.

In Vitro Evaluation of Enteric-Coated HPMC Capsules-Effect of Formulation Factors on Product Performance

A comparative study on different enteric-coated hard capsules was performed. The influence of different formulation factors like choice of enteric polymer, triethyl citrate (TEC) concentration (plasticizer), talc concentrations (anti-tacking agent), and different coating process parameters on the sealing performance of the capsule and the disintegration time were investigated. Furthermore, the influence of different disintegration test methods (with disc vs. without disc and 50 mM U.S. Pharmacopoeia (USP) buffer pH 6.8 vs. biopredictive 15 mM phosphate buffer pH 6.5) was evaluated. All formulations showed sufficient but not equivalent acid resistance when tested. Polymer type was the main factor influencing the capsule sealing and disintegration time. In addition, TEC and talc could affect the performance of the formulation. Regarding the choice of the disintegration test method, the presence of a disc had for the most part only limited influence on the results. The choice of disintegration buffer was found to be important in identifying differences between the formulations.

Molecular regulators of lipid metabolism in the intestine - Underestimated therapeutic targets for obesity?

The incidence of obesity and type 2 diabetes continues to rise across the globe necessitating the need to identify new therapeutic approaches to manage these diseases. In this review, we explore the potential for therapeutic interventions focussed on the intestinal epithelium, by targeting the role of this tissue in lipid uptake, lipid-mediated cross talk and lipid oxidation. We focus initially on ongoing strategies to manage obesity by targeting the essential role of the intestinal epithelium in lipid uptake, and in mediating tissue cross talk to regulate food intake. Subsequently, we explore a previously underestimated capacity of intestinal epithelial cells to oxidize fatty acids. In this context, we describe recent findings which have unveiled a key role for the peroxisome proliferator-activated receptor (PPAR) family of nuclear receptors and histone deacetylases (HDACs) in the regulation of lipid oxidation genes in enterocytes and how targeted genetic manipulation of these factors in enterocytes reduces weight gain, identifying intestinal PPARs and HDACs as potential therapeutic targets in the management of obesity.

OPTICORE™, an innovative and accurate colonic targeting technology

Inflammatory bowel disease (IBD) is a debilitating condition, estimated to affect 7 million people worldwide. Current IBD treatment strategies are substandard, relying on colonic targeting using the pH gradient along the gastrointestinal tract. Here, we describe an innovative colonic targeting concept, OPTICORE™ coating technology. OPTICORE™ combines two release triggers (pH and enzyme: Phloral™) in the outer layer, with an inner layer promoting a release acceleration mechanism (Duocoat™). The technology comprises an inner layer of partially neutralized enteric polymer with a buffer agent and an outer layer of a mixture of Eudragit® S and resistant starch. 5-aminosalicylic acid (5-ASA) tablets were coated with different inner layers, where the type of polymer, buffer salt concentration and pH of neutralization, were investigated for drug release acceleration. Buffer capacity of polymethacrylate neutralized polymer significantly contributes to the buffer capacity of the inner layer formulation, while buffer salt concentration is a major contributor to dispersion buffer capacity in the case of hypromellose enteric polymer formulations. An interplay between buffer capacity, pH and ionic strength contributes to an accelerated drug release. Resistant starch does not impact the enteric properties but allows for drug release mediated by colonic bacterial enzymes, ensuring complete drug release. Therefore, OPTICORE™ technology is designed to offer significant advantages over standard enteric coatings, particularly allowing for more accurate colonic drug delivery in ulcerative colitis patients.

A Cyclodextrin-Based Controlled Release System in the Simulation of In Vitro Small Intestine

A novel cyclodextrin (CD)-based controlled release system was developed in the small intestine to control the rate of drug release, on the premise of enteric-coated tablets. The system was designed based on the enzymes exogenous β-cyclodextrin glycosyltransferase (β-CGTase) and endogenous maltase-glucoamylase (MG), wherein MG is secreted in the small intestine and substituted by a congenerous amyloglucosidase (AG). The vanillin-/curcumin-β-CD complexes were prepared and detected by Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), and host CD degradation was measured based on the glucose yield. The combination of β-CGTase and AG was also functional in the CD complex system. The variations in the concentrations of added β-CGTase, with AG constantly in excess, could effectively alter the rate of host CD degradation and guest release by monitoring glucose production and color disappearance, thus, demonstrating that guest release in the CD complex system could be precisely controlled by changing the amount of β-CGTase used. Thus, the in vitro simulation of the system indicated that a novel controlled release system, based on endogenous MG, could be established in the small intestine. The CD-based controlled release system can be potentially applied in drug delivery and absorption in the small intestine.

Lego-Inspired Capsular Devices for the Development of Personalized Dietary Supplements: Proof of Concept With Multimodal Release of Caffeine

Dietary supplement companies have recently started to focus on the personalization of products and the improvement of the relevant performance. In this respect, a versatile, easy-to-handle capsular delivery platform with customizable content and release kinetics was here proposed and evaluated after filling with caffeine as a model dietary ingredient. In particular, capsular devices comprising 1 to 3 independent inner compartments were attained by Lego-inspired assembly of matching modular units with different wall compositions, manufactured by injection molding and fused deposition modeling 3D printing. Accordingly, one-, two- and three-pulse release profiles of the dietary ingredient were obtained from differently assembled devices following the breakup of the compartments occurring promptly (immediate-release), on pH change (delayed-release) or after tunable lag times (pulsatile-release). The latter release mode would enable the onset of the stimulating effect of caffeine at different times of the day after a single administration when convenient. The performance of each individual compartment only depended on the composition (i.e., promptly soluble, swellable/soluble or enteric soluble polymers) and thickness of its own wall, while it was not affected by the composition and number of joined modular units. Moreover, the delivery platform was extended to include an external gastroresistant shell enclosing previously assembled devices.

Engineering of Naproxen Loaded Polymer Hybrid Enteric Microspheres for Modified Release Tablets: Development, Characterization, in silico Modelling and in vivo Evaluation

BACKGROUND

Naproxen (NP) is a non-steroidal anti-inflammatory drug with poor aqueous solubility and low oral bioavailability, which may lead to therapeutic failure. NP causes crucial GIT irritation, bleeding, and peptic and duodenal ulcers.

PURPOSE OF THE STUDY

This study aimed to engineer and characterize polymer hybrid enteric microspheres using an integrated (experimental and molecular modelling) approach with further development to solid dosage form with modified drug release kinetics and improved bioavailability.

MATERIALS AND METHODS

NP loaded polymer hybrid enteric microspheres (PHE-Ms) were fabricated by using a modified solvent evaporation technique coupled with molecular modelling (MM) approach. The PHE-Ms were characterized by particle size, distribution, morphology, crystallinity, EE, drug-polymer compatibility, and DSC. The optimized NP loaded PHE-Ms were further subjected to downstream procedures including tablet dosage form development, stability studies and comparative in vitro-in vivo evaluation.

RESULTS

The hydrophobic polymer EUD-L100 and hydrophilic polymer HPMC-E5 delayed and modified drug release at intestinal pH while imparting retardation of NP release at gastric pH to diminish the gastric side effects. The crystallinity of the NP loaded PHE-Ms was established through DSC and P (XRD). The particle size for the developed formulations of PEH-Ms (M1-M5) was in the range from 29.06 ±7.3-74.31 ± 17.7 μm with Span index values of 0.491-0.69, respectively. The produced NP hybrid microspheres demonstrated retarded drug release at pH 1.2 and improved dissolution at pH 6.8. The in vitro drug release patterns were fitted to various release kinetic models and the best-followed model was the Higuchi model with a release exponent "n" value > 0.5. Stability studies at different storage conditions confirmed stability of the NP loaded PHE-Ms based tablets (P<0.05). The molecular modelling (MM) study resulted in adequate binding energy of co-polymer complex SLS-Eudragit-HPMC-Naproxen (-3.9 kcal/mol). In contrast to the NP (unprocessed) and marketed formulations, a significant increase in the Cmax of PHE-MT1 (44.41±4.43) was observed.

CONCLUSION

The current study concludes that developing NP loaded PHE-Ms based tablets could effectively reduce GIT consequences with restored therapeutic effects. The modified release pattern could improve the dissolution rate and enhancement of oral bioavailability. The MM study strengthens the polymer-drug relationship in microspheres.

Taste masking of propranolol hydrochloride by microbeads of EUDRAGIT® E PO obtained with prilling technique for paediatric oral administration

The purpose of this study was to develop a new solid paediatric formulation for propranolol hydrochloride (PR). This drug is used to treat various paediatric diseases, and recently received clearance to treat haemangioma. However, PR has a bitter salty taste that does not facilitate high rates of compliance among children, especially in liquid formulations. In addition, the solid formulations are designed for adults and often their dosage is not suitable for children that require a flexible dose based on their weight. Therefore, matrix microbeads of EUDRAGIT® E PO containing PR were manufactured to overcome these limitations. Nine different samples were prepared using the prilling-congealing technique with high yield. Using 2 nozzles, 300 and 450 μm (code n), the diameters obtained of microbeads (from 333 to 699 μm) were homogenous and appropriate to be swallowed by children. In this study, the ratio drug:matrix for the microbeads was also examined in detail: 1:25 (F₁), 1:15 (F₂) and 1:10 (F₃) in aqueous and tert-butyl alcohol/aqueous (code t) media. Most of the examined microbeads were characterized by high percentage of encapsulation efficiency (22-100%) and drug loading (22-77 mg of drug per g of matrix) effective for the administration of low and high doses of PR. SEM analysis revealed a matrix with a radial or a spongy structure, with numerous pores that generated soft floating microbeads in aqueous solution. Release studies confirmed a low release and dissolution of the drug in artificial saliva, mainly F_1n > F₁ > F_2nt, and a prompt dissolution in simulated gastric media. Finally, electronic tongue measurements revealed the ability of these formulations to mask the bitter drug taste, especially for the sample with a ratio 1:25 (F_1n and F₁). These samples were chemically and physically stable for six months. In conclusion, the projected microbeads F₁, and F_1n reached the goal of the study, and could be proposed as new solid oral formulations dedicated to use by children.

Adjustment of triple shellac coating for precise release of bioactive substances with different physico-chemical properties in the ileocolonic region

Formulations for the controlled release of substances in the human terminal ileum and colon are essential to target the gut microbiome and its interactions with the intestinal mucosa. In contrast to pharmaceutical enteric coatings, reliable food-grade alternatives are still scarce. Shellac coatings have been used for various active ingredients, but their stability is affected by the physicochemical properties of the encapsulated substances. It is well known, that shellac release can be modulated by an acidic subcoating. Here, we hypothesized that a triple shellac coating with an adjusted intermediate coating (acidic or alkaline) can be effectively used to counteract the differences in pH value of various encapsulated substances, allowing a precise targeting of the desired release pH value. First, the system was tested with riboflavin 5'-monophosphate sodium salt dihydrate (RMSD) as a characteristic model substance. Secondly, it was transferred to nicotinic acid (NA) and nicotinamide (NAM) as bioactive compounds with different physio-chemical properties: NAM, an alkaline crystalline and highly water-soluble substance, led to a premature release from conventional shellac microcapsules, whereas RMSD and NA with their medium solubility and neutral to acidic pH properties delayed the shellac dissolution. A precise modulation of the release profile of each substance was possible by the addition of different intermediate subcoatings: an acidic layer with citric acid counteracted the premature release of the alkaline and highly soluble NAM. In contrast, an alkaline sodium bicarbonate intermediate subcoating enhanced shellac swelling and delayed the release of NA and RMSD. In conclusion, the novel triple-layer shellac coating provides a much higher adaptability and reliability for nutritional formulations aiming at a targeted release in the ileocolonic region.

Evaluation of the in vitro Antitumor Activity of Nanostructured Cyclotides in Polymers of Eudragit® L 100-55 and RS 30 D

Background:

Cancer is a major cause of mortality and morbidity and given the limitations of many current cancer drugs, there is great need to discover and develop novel treatments. An alternative to the conventional drug discovery path is to exploit new classes of natural compounds such as cyclotides. This peptide family is characterized by linked C- and N-termini and a structural fold called the cyclic cystine knot (CCK). The CCK fold is responsible for the exceptional enzymatic, chemical and thermal stability of cyclotides.

Methods:

In the present study, an alternative to traditional cancer treatments, involving new nanomaterials and nanocarriers allowing efficient cyclotide delivery, is proposed. Using the polymers Eudragit&#174; L 100-55 and RS 30 D, the cyclotides kalata B2 and parigidin-br1 (PBR1) were nanocapsulated, and nanoparticles 91 nm and 188 nm in diameter, respectively, were produced.

Results:

An encapsulation rate of up to 95% was observed. In vitro bioassays showed that the nanostructured cyclotides were partially able to control the development of the colorectal adenocarcinoma cell line CACO2 and the breast cancer cell line MCF-7.

Conclusion:

Data reported herein indicate that nanoformulated cyclotides exhibit antitumor activity and sustained drug release. Thus, the system using Eudragit&#174; nanocapsules seems to be efficient for cyclotide encapsulation and probably could be used to target specific tumors in future studies.

3D printed medicines: A new branch of digital healthcare

Three-dimensional printing (3DP) is a highly disruptive technology with the potential to change the way pharmaceuticals are designed, prescribed and produced. Owing to its low cost, diversity, portability and simplicity, fused deposition modeling (FDM) is well suited to a multitude of pharmaceutical applications in digital health. Favourably, through the combination of digital and genomic technologies, FDM enables the remote fabrication of drug delivery systems from 3D models having unique shapes, sizes and dosages, enabling greater control over the release characteristics and hence bioavailability of medications. In turn, this system could accelerate the digital healthcare revolution, enabling medicines to be tailored to the individual needs of each patient on demand. To date, a variety of FDM 3D printed medical products (e.g. implants) have been commercialised for clinical use. However, within pharmaceuticals, certain regulatory hurdles still remain. This article reviews the current state-of-the-art in FDM technology for medical and pharmaceutical research, including its use for personalised treatments and interconnection within digital health networks. The outstanding challenges are also discussed, with a focus on the future developments that are required to facilitate its integration within pharmacies and hospitals.

All disease begins in the gut: Influence of gastrointestinal disorders and surgery on oral drug performance

The term "disease" conjures a plethora of graphic imagery for many, and the use of drugs to combat symptoms and treat underlying pathology is at the core of modern medicine. However, the effects of the various gastrointestinal diseases, infections, co-morbidities and the impact of gastrointestinal surgery on the pharmacokinetic and pharmacodynamic behaviour of drugs have been largely overlooked. The better elucidation of disease pathology and the role of underlying cellular and molecular mechanisms have increased our knowledge as far as diagnoses and prognoses are concerned. In addition, the recent advances in our understanding of the intestinal microbiome have linked the composition and function of gut microbiota to disease predisposition and development. This knowledge, however, applies less so in the context of drug absorption and distribution for orally administered dosage forms. Here, we revisit and re-evaluate the influence of a portfolio of gastrointestinal diseases and surgical effects on the functionality of the gastrointestinal tract, their implications for drug delivery and attempt to uncover significant links for clinical practice.

Unpredictable Performance of pH-Dependent Coatings Accentuates the Need for Improved Predictive in Vitro Test Systems

First introduced in the second half of the 19th century, enteric coatings are commonly used to protect acid-labile drugs, reduce the risk of gastric side effects due to irritating drugs, or for local drug delivery to the lower gastrointestinal (GI) tract. The currently available enteric-coatings are based on pH-sensitive weakly acidic polymers. Despite the long history of their use, the causes behind their performance often being unpredictable have not been properly investigated with most of the attention being focused only on the gastric emptying. However, little attention has been given to the postgastric emptying disintegration and dissolution of these dosage forms. This lack of attention has contributed to the difficulty in predicting the in vivo behavior of these dosage forms and to cases of bioavailability problems with some enteric-coated products. Therefore, increased attention needs to be given to this issue.

Fabricating a Shell-Core Delayed Release Tablet Using Dual FDM 3D Printing for Patient-Centred Therapy

PURPOSE

Individualizing gastric-resistant tablets is associated with major challenges for clinical staff in hospitals and healthcare centres. This work aims to fabricate gastric-resistant 3D printed tablets using dual FDM 3D printing.

METHODS

The gastric-resistant tablets were engineered by employing a range of shell-core designs using polyvinylpyrrolidone (PVP) and methacrylic acid co-polymer for core and shell structures respectively. Filaments for both core and shell were compounded using a twin-screw hot-melt extruder (HME). CAD software was utilized to design a capsule-shaped core with a complementary shell of increasing thicknesses (0.17, 0.35, 0.52, 0.70 or 0.87 mm). The physical form of the drug and its integrity following an FDM 3D printing were assessed using x-ray powder diffractometry (XRPD), thermal analysis and HPLC.

RESULTS

A shell thickness ≥0.52 mm was deemed necessary in order to achieve sufficient core protection in the acid medium. The technology proved viable for incorporating different drug candidates; theophylline, budesonide and diclofenac sodium. XRPD indicated the presence of theophylline crystals whilst budesonide and diclofenac sodium remained amorphous in the PVP matrix of the filaments and 3D printed tablets. Fabricated tablets demonstrated gastric resistant properties and a pH responsive drug release pattern in both phosphate and bicarbonate buffers.

CONCLUSIONS

Despite its relatively limited resolution, FDM 3D printing proved to be a suitable platform for a single-process fabrication of delayed release tablets. This work reveals the potential of dual FDM 3D printing as a unique platform for personalising delayed release tablets to suit an individual patient's needs.

Preparation and In Vitro-In Vivo Evaluation of Sustained-Release Matrix Pellets of Capsaicin to Enhance the Oral Bioavailability

Capsaicin has multiple pharmacological activities including antioxidant, anticancer, and anti-inflammatory activities. However, its clinical application is limited due to its poor aqueous solubility, gastric irritation, and low oral bioavailability. This research was aimed at preparing sustained-release matrix pellets of capsaicin to enhance its oral bioavailability. The pellets comprised of a core of solid-dispersed capsaicin mixed with microcrystalline cellulose (MCC) and hydroxypropyl cellulose (HPMC) and subsequently coating with ethyl cellulose (EC) were obtained by using the technology of extrusion/spheronization. The physicochemical properties of the pellets were evaluated through scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). Besides, the in vitro release, in vivo absorption, and in vitro-in vivo correlation were also assessed. More importantly, the relative bioavailability of the sustained-release matrix pellets was studied in fasted rabbits after oral administration using free capsaicin and solid dispersion as references. The oral bioavailability of the matrix pellets and sustained-release matrix pellets of capsaicin was improved approximately 1.98-fold and 5.34-fold, respectively, compared with the free capsaicin. A good level A IVIVC (in vitro-in vivo correlation) was established between the in vitro dissolution and the in vivo absorption of sustained-release matrix pellets. All the results affirmed the remarkable improvement in the oral bioavailability of capsaicin owing to the successful preparation of its sustained-release matrix pellets.

Evaluation of powder, solution and suspension layering for the preparation of enteric coated pellets

Gastro-resistant pellets were prepared by use of three different drug loading techniques (powder layering, solution layering and suspension layering) and two different enteric coating techniques (powder layering and suspension layering). Pellets produced by different layering techniques were compared in terms of morphological characteristics, content of drug, release properties and stability. Drug loaded pellets produced by the use of powder layering had much more pronounced surface roughness in comparison to other tested techniques. Higher weight gains of enteric polymer were needed to achieve the same level of gastric resistance when powder layering was employed to apply enteric layer than when it was applied by suspension layering. Both tested techniques of enteric coating application enabled complete dissolution of drug in buffer stage of dissolution test. Suspension layering proved to be superior to other techniques both in drug loading and enteric layering phase.

Interpolyelectrolyte complexes of Eudragit® EPO with hypromellose acetate succinate and Eudragit® EPO with hypromellose phthalate as potential carriers for oral controlled drug delivery

The objective of this study was to compare a novel controlled release tablet formulation based on interpolyelectrolyte complex (PEC). Interpolymer interactions between the countercharged polymers like Eudragit® EPO (polycation) and hypromellose acetate succinate (polyanion) and Eudragit® EPO and hypromellose phthalate (polyanion) were investigated with a view to their use in per oral controlled release drug delivery systems. The formation of inter-macromolecular ionic bonds between cationic polymer and anionic polymer was investigated using Fourier transform infrared (FT-IR) spectroscopy and differential scanning calorimetry. The FT-IR spectra of the tested polymeric matrices are characterized by visible changes in the observed IR region indicating the interaction between chains of two oppositely charged copolymers. The performance of the in situ formed PEC as a matrix for controlled release of drugs was evaluated, using acetaminophen as a model drug. The dissolution data of these matrices were fitted to different dissolution models. It was found that drug release followed zero-order kinetics and was controlled by the superposition of the diffusion and erosion. These profiles could be controlled by conveniently modifying the proportion of the polymer ratio, polymer type, and polymer concentration the in the tablets.

Predicting the gastrointestinal behaviour of modified-release products: utility of a novel dynamic dissolution test apparatus involving the use of bicarbonate buffers

The establishment of physiologically relevant in vitro-in vivo correlations (IV-IVCs) is key for any biorelevant dissolution test. Historically, bicarbonate buffers have produced better correlations than compendial phosphate buffered media, though such tests are usually performed at a constant pH experiment, overlooking the notion that the pH of the luminal fluids is variable and fluctuating. In this work, we have devised a dynamic dissolution test method employing a physiological bicarbonate buffer under pH conditions of the proximal gut in order to assess the dissolution behaviour of various enteric polymer-coated (gastro-resistant) prednisolone tablets. The pH of the media is modulated and controlled by an Auto pH System™ which exploits the physiological equilibria between [H2CO3] and [HCO3(-)], to match it to the aboral change in pH with transit of the dosage form through the proximal small intestine (from pH 5.6 up to 6.8). The lag time values for an accelerated release and standard EUDRAGIT(®) L30D-55 coated formulation (25 min and 60 min, respectively) were close to the previously reported initial tablet disintegration time data obtained in-vivo by γ-scintigraphy (28 min and 66 min, respectively). Dissolution of alternative delayed release coated products was also better discriminated in the dynamic buffer system. These data confirm the dynamic dissolution system provides a robust and reliable platform to predict the in vivo fate of oral products in a laboratory setting.

Eudragit L/HPMCAS blend enteric-coated lansoprazole pellets: enhanced drug stability and oral bioavailability

The objectives of the present work were to use blends of Eudragit L and hydroxypropyl methylcellulose acetate succinate (HPMCAS) as enteric film coatings for lansoprazole (LSP) pellets. The enteric-coated pellets were prepared with a fluid-bed coater. The influence of the blend ratio, type of plasticizer, plasticizer level, coating level, and curing conditions on gastric stability in vitro drug release and drug stability was evaluated. Furthermore, the bioavailability of the blend-coated pellets in beagle dogs was also performed. The blend-coated pellets exhibited significant improvement of gastric stability and drug stability compared to the pure polymer-coated pellets. Moreover, the AUC values of blend-coated pellets were greater than that of the pure polymer-coated pellets. It was concluded that the using blends of Eudragit L and HPMCAS as enteric film coatings for LSP pellets improved the drug stability and oral bioavailability.

Rapid profiling of enteric coated drug delivery spheres via Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS)

There is an increased trend towards the use of drug and enteric coated sugar spheres for controlled oral delivery of active pharmaceutical ingredients (API).

Overview of drug product development

The process for developing drug delivery systems has evolved over the past two decades with more scientific rigor, involving a collaboration of various fields, i.e., biology, chemistry, engineering, and pharmaceutics. Drug products, also commonly known in the pharmaceutical industry as formulations or "dosage forms," are used for administering the active pharmaceutical ingredient (API) for purposes of assessing safety in preclinical models, early- to late-phase human clinical trials, and for routine clinical/commercial use. This overview discusses approaches for creating small-molecule API dosage forms, from preformulation to commercial manufacturing.

Assessment of the pharmaceutical quality of marketed enteric coated pantoprazole sodium sesquihydrate products

Pantoprazole sodium sesquihydrate (PSS) is a proton pump inhibitor, used in acid-related disorders, like peptic ulcer and gastroesophageal reflux. Increasing the number of pantoprazole containing products in the market, raises questions of its efficacy and generic substitution. The pharmaceutical quality of 6 generic PSS enteric coated tablets in 2 local markets was assessed relative to the innovator product (pantozol®). Uniformity of dosage unit, disintegration and in vitro drug release were determined using United States pharmacopeia for delayed release tablets. The similarity factor (f2) was assessed using the FDA recommended approach (f2 similarity factor). The content uniformity of the innovator product was 98.39% of the labeled claim with RSD value of 1.08%, while the content of generic products ranged from 96.98% to 98.80% with RSD values of 1.24-2.19%. All the products showed no disintegration, cracks or swelling in 0.1 N HCl, except product 1, which showed complete disintegration after 20 min. However, the disintegration of all the products in phosphate buffer met USP requirements. Dissolution of tablets in 0.1 N HCl showed no drug release after 2 h except product 1 in which one tablet showed a drug release more than 10% at acid stage level A1. In addition, three tablets of this product showed dissolution of 45%, 48% and 69% at acid stage level A2. The similarity factor f2 of the products was between 71 and 74 indicating the similarity in dissolution profiles of all the products in accordance to FDA requirements, except product 1 in which f2 value was 18.67.