Colon Drug Delivery Systems Based on Swellable and Microbially Degradable High-Methoxyl Pectin: Coating Process and In Vitro Performance.

Oral colon delivery systems based on a dual targeting strategy, harnessing time- and microbiota-dependent release mechanisms, were designed in the form of a drug-containing core, a swellable/biodegradable polysaccharide inner layer and a gastroresistant outer film. High-methoxyl pectin was employed as the functional coating polymer and was applied by spray-coating or powder-layering. Stratification of pectin powder required the use of low-viscosity hydroxypropyl methylcellulose in water solution as the binder. These coatings exhibited rough surfaces and higher thicknesses than the spray-coated ones. Using a finer powder fraction improved the process outcome, coating quality and inherent barrier properties in aqueous fluids. Pulsatile release profiles and reproducible lag phases of the pursued duration were obtained from systems manufactured by both techniques. This performance was confirmed by double-coated systems, provided with a Kollicoat® MAE outer film that yielded resistance in the acidic stage of the test. Moreover, HM pectin-based coatings manufactured by powder-layering, tested in the presence of bacteria from a Crohn's disease patient, showed earlier release, supporting the role of microbial degradation as a triggering mechanism at the target site. The overall results highlighted viable coating options and in vitro release characteristics, sparking new interest in naturally occurring pectin as a coating agent for oral colon delivery.

Cushion-coated pellets for tableting without external excipients.

Multiple-unit dosage forms prepared by compacting pellets offer important manufacturing and compliance advantages over pellet-filled capsules. However, compaction may negatively affect the release control mechanism of pellets, and subunits may not be readily available after intake. Application of a cushioning layer to the starting units is here proposed as a strategy to obtain tablets with satisfactory mechanical strength, rapid disintegration and maintenance of the expected release profile of individual subunits while avoiding the use of mixtures of pellets and excipients to promote compaction and limit the impact of the forces involved. Cushion-coating with PEG1500, a soft and soluble material, was proved feasible provided that the processing temperature was adequately controlled. Cushioned gastro-resistant pellets were shown to consolidate under relatively low compaction pressures, which preserved their inherent release performance after tablet disintegration. Adhesion problems associated with the use of PEG1500 were overcome by applying an outer Kollicoat® IR film. Through design of experiment (DoE), robustness of the proposed approach was demonstrated, and the formulation as well as tableting conditions were optimized. The tableted cushion-coated pellet systems manufactured would allow a relatively high load of modified-release units to be conveyed, thus setting out a versatile and scalable approach to oral administration of multiple-unit dosage forms.

Guar gum as a microbially degradable component for an oral colon delivery system based on a combination strategy: formulation and in vitro evaluation.

Oral colon delivery has widely been pursued exploiting naturally occurring polysaccharides degraded by the resident microbiota. However, their hydrophilicity may hinder the targeting performance. The aim of the present study was to manufacture and evaluate a double-coated delivery system leveraging intestinal microbiota, pH, and transit time for reliable colonic release. This system comprised a tablet core, a hydroxypropyl methylcellulose (HPMC) inner layer and an outer coating based on Eudragit® S and guar gum. The tablets were loaded with paracetamol, selected as a tracer drug because of the well-known analytical profile and lack of major effects on bacterial viability. The HPMC and Eudragit® S layers were applied by film-coating. Tested for in vitro release, the double-coated systems showed gastroresistance in 0.1 N HCl followed by lag phases of consistent duration in phosphate buffer pH 7.4, imparted by the HPMC layer and synergistically extended by the Eudragit® S/guar gum one. In simulated colonic fluid with fecal bacteria from an inflammatory bowel disease patient, release was faster than in the presence of ß-mannanase and in control culture medium. The bacteria-containing fluid was obtained by an experimental procedure making multiple tests possible from a single sampling and processing run. Thus, the study conducted proved the feasibility of the delivery system and ability of guar gum to trigger release in the presence of colon bacteria without impairing the barrier properties of the coating. Finally, it allowed an advantageous simulated colonic fluid preparation procedure to be set up, reducing the time, costs, and complexity of testing and enhancing replicability.

Organ-Retentive Osmotically Driven System (ORODS): A Novel Expandable Platform for in Situ Drug Delivery.

Drug delivery systems capable of being retained within hollow organs allow the entire drug dose to be delivered locally to the disease site or to absorption windows for improved systemic bioavailability. A novel Organ-Retentive Osmotically Driven System (ORODS) was here proposed, obtained by assembling drug-containing units having prolonged release kinetics with osmotic units used as increasing volume compartments. Particularly, prototypes having H-shape design were conceived, manufactured and evaluated. Such devices were assembled by manually inserting a tube made of regenerated cellulose (osmotic unit) into the holes of two perforated hydrophilic tableted matrices containing paracetamol as a tracer drug. The osmotic unit was obtained by folding and gluing a plain regenerated cellulose membrane and loading sodium chloride inside. When immersed in aqueous fluids, this compartment expanded to approximately 80% of its maximum volume within 30 min of testing, and a plateau was maintained for about 6 h. Subsequently, it slowly shrank to approximately 20% of the maximum volume in 24 h, which would allow for physiological emptying of the device from hollow organs. While expanding, the osmotic unit acquired stiffness. Drug release from H-shaped ORODSs conveyed in hard-gelatin capsules was shown to be prolonged for more than 24 h.

Towards 4D printing in pharmaceutics.

Four-dimensional printing (4DP) is emerging as an innovative research topic. It involves the use of smart materials for three-dimensional printing (3DP) of items that change their shape after production, in a programmed way over time, when exposed to appropriate external non-mechanical stimuli (moisture, electric or magnetic fields, UV, temperature, pH or ion composition). In the performance of 4D printed devices, time is involved as the 4th dimension. 4D smart structures have been known for many years in the scientific literature, well before the advent of 3D printing, and the concepts of shape evolution as well as self-assembly have been applied to drug delivery at the nano-, micro- and macro-scale levels. The neologism "4DP" was coined by Tibbits, Massachusetts Institute of Technology, in 2013, who also showed the earliest examples of 4D printed objects. Since then, smart materials have often been combined with additive manufacturing, which makes production of complex shapes easy to achieve: going beyond 3DP, 4D printed items are no static objects. Two main categories of raw materials have been employed for 4DP: shape memory polymers (SMPs) and shape morphing hydrogels (SMHs). In principle, all types of 3D printers could be used for 4DP. In this article, examples of systems for use in the biomedical field, such as stents and scaffolds, and in drug delivery are reviewed, with special emphasis on indwelling devices for retention in the urinary bladder and in the stomach.

Investigation on the use of fused deposition modeling for the production of IR dosage forms containing Timapiprant.

The present work focused on evaluating the feasibility of fused deposition modeling (FDM) in the development of a dosage form containing Timapiprant (TMP), also known as CHF6532, which is a novel active molecule indicated in the potential treatment of eosinophilic asthma upon oral administration. The resulting product could be an alternative, with potential towards personalization, of immediate release (IR) tablets used in the clinical studies. Formulations based on different polymeric carriers were screened, leading to the identification of a polyvinyl alcohol-based one, which turned out acceptable for versatility in terms of active ingredient content, printability and dissolution performance (i.e. capability to meet the dissolution specification set, envisaging >80% of the drug dissolved within 30 min). Following an in-depth evaluation on the influence of TMP solid state and of the voids volume resulting from printing on dissolution, few prototypes with shapes especially devised for therapy customization were successfully printed and were compliant with the dissolution specification set.

Time-Based Formulation Strategies for Colon Drug Delivery.

Despite poor absorption properties, delivery to the colon of bioactive compounds administered by the oral route has become a focus of pharmaceutical research over the last few decades. In particular, the high prevalence of Inflammatory Bowel Disease has driven interest because of the need for improved pharmacological treatments, which may provide high local drug concentrations and low systemic exposure. Colonic release has also been explored to deliver orally biologics having gut stability and permeability issues. For colon delivery, various technologies have been proposed, among which time-dependent systems rely on relatively constant small intestine transit time. Drug delivery platforms exploiting this physiological feature provide a lag time programmed to cover the entire small intestine transit and control the onset of release. Functional polymer coatings or capsule plugs are mainly used for this purpose, working through different mechanisms, such as swelling, dissolution/erosion, rupturing and/or increasing permeability, all activated by aqueous fluids. In addition, enteric coating is generally required to protect time-controlled formulations during their stay in the stomach and rule out the influence of variable gastric emptying. In this review, the rationale and main delivery technologies for oral colon delivery based on the time-dependent strategy are presented and discussed.

Evaluation of Newly Designed and Traditional Punches in Manufacturing of Scored ODTs.

To overcome difficulties in splitting, uneven breaking and inconsistent dosing frequently reported with scored tablets, a novel punch was proposed for the manufacturing of easy breakable tablets (EBTs). In this work, the performance of the EBT punch was investigated vs. a ridged one for traditional breakable tablets (TBTs) using a furosemide powder formulation for orally disintegrating tablets (ODTs). A Face Centered Central Composite Design was applied to investigate the influence of punch type, compaction force, tablet weight and press rotation speed on the mechanical properties of ODTs, their behavior in aqueous fluids and aptitude for splitting. Mass uniformity and adequate crushing strength, friability, water uptake, disintegration and wetting times were obtained from both TBTs and EBTs. Interestingly, more favorable splitting behavior was shown by tablets manufactured by the novel punch, in view of lower mass loss and portion mass variability after breaking. The ease of breaking, accuracy of subdivision and mass loss of ODTs were also evaluated by a volunteer (n = 20) panel test. Less difficulty was found in splitting EBTs than TBTs (p < 0.05), and a larger number of tablets were properly broken into four parts. Thus, this study proved the usefulness of the EBT punch in overcoming drawbacks associated with divisible tablets.

Administration strategies and smart devices for drug release in specific sites of the upper GI tract.

Targeting the release of drugs in specific sites of the upper GI tract would meet local therapeutic goals, improve the bioavailability of specific drugs and help overcoming compliance-related limitations, especially in chronic illnesses of great social/economic impact and involving polytherapies (e.g. Parkinson's and Alzeimer's disease, tubercolosis, malaria, HIV, HCV). It has been traditionally pursued using gastroretentive (GR) systems, i.e. low-density, high-density, magnetic, adhesive and expandable devices. More recently, the interest towards oral administration of biologics has prompted the development of novel drug delivery systems (DDSs) provided with needles and able to inject different formulations in the mucosa of the upper GI tract and particularly of esophagus, stomach or small intestine. Besides comprehensive literature analysis, DDSs identified as smart devices in view of their high degree of complexity in terms of design, working mechanism, materials employed and manufacturing steps were discussed making use of graphic tools.

Intravesical drug delivery approaches for improved therapy of urinary bladder diseases.

Diseases of the urinary bladder have high incidence rates and burden healthcare costs. Their pharmacological treatment involves systemic and local drug administration. The latter is generally accomplished through instillation of liquid formulations and requires repeated or long-term catheterization that is associated with discomfort, inflammation and bacterial infections. Consequently, compliance issues and dropouts are frequently reported. Moreover, instilled drugs are progressively diluted as the urine volume increases and rapidly excreted. When penetration of drugs into the bladder wall is needed, the poor permeability of the urothelium has also to be accounted for. Therefore, much research effort is spent to overcome these hurdles, thereby improving the efficacy of available therapies. Particularly, indwelling delivery systems suited for i) insertion into the bladder through the urethra, ii) intra-organ retention and prolonged release for the desired time lapse, iii) final elimination, either spontaneous or by manual removal, have been proposed to reduce the number of catheterization procedures and reach higher drug levels at the target site. Vesical retention of such devices is allowed by the relevant expansion that can either be triggered from the outside or achieved exploiting elastic and purposely 4D printed shape memory materials. In this article, the main rationales and strategies for improved intravesical delivery are reviewed.

Cellulase as an "active" excipient in prolonged-release HPMC matrices: A novel strategy towards zero-order release kinetics.

Hydrophilic matrices are of utmost interest for oral prolonged release of drugs. However, they show decreasing release rate over time, mainly due to lengthening of the diffusional pathway across the gel formed upon glass-rubber transition of the polymer. Therefore, achievement of zero-order release kinetics, which could reflect in constant drug plasma levels, is still an open issue. With the aim of improving the release performance of hydroxypropyl methylcellulose (HPMC) systems, the use of cellulolytic enzymes was proposed to aid erosion of the swollen matrix, thereby counteracting the release rate decrease particularly toward the end of the process. The effectiveness of this strategy was evaluated by studying the mass loss and drug tracer release from tableted matrices consisting of high-viscosity HPMC (Methocel® K4M), Acetaminophen and increasing amounts (0.5-10% on HPMC) of a cellulolytic product (Sternzym® C13030). A faster erosion and progressive shift to linearity of the overall release profiles were observed as a function of the enzyme concentration. Release was markedly linear from matrices containing 5 and 10% Sternzym® C13030. In partially coated matrices with these cellulase concentrations, such results were in agreement with data of erosion and swelling front movement, which exhibited early and long-lasting synchronization.

The Chronotopic™ System for Pulsatile and Colonic Delivery of Active Molecules in the Era of Precision Medicine: Feasibility by 3D Printing via Fused Deposition Modeling (FDM).

The pulsatile-release Chronotopic™ system was conceived of as a drug-containing core surrounded by a coat made of swellable/soluble hydrophilic polymers, the latter being able to provide a programmable lag phase prior to drug liberation. This system was also proposed in a colon-targeting configuration, entailing a gastroresistant film to prevent early interaction of the inner coat with gastric fluids and enabling the attainment of a lag phase matching the small intestinal transit time. Over the years, various multiple-step manufacturing processes have been tested for the fabrication of the Chronotopic™ system in both its configurations. This work focused on the evaluation of 3D printing by fused deposition modeling in view of its potential towards product personalization, on demand one-step manufacturing and efficient scale down of batches. The feasibility of each part of the Chronotopic™ system was independently investigated starting from in-house made filaments, characterizing the resulting specimens for physico-technological and performance characteristics. The printing parameters identified as suitable during the set-up phase were then used to fabricate prototypes either in a single step for the pulsatile configuration or following two different fabrication approaches for the colon-targeting one.

Shape memory materials and 4D printing in pharmaceutics.

Shape memory materials (SMMs), including alloys and polymers, can be programmed into a temporary configuration and then recover the original shape in which they were processed in response to a triggering external stimulus (e.g. change in temperature or pH, contact with water). For this behavior, SMMs are currently raising a lot of attention in the pharmaceutical field where they could bring about important innovations in the current treatments. 4D printing involves processing of SMMs by 3D printing, thus adding shape evolution over time to the already numerous customization possibilities of this new manufacturing technology. SMM-based drug delivery systems (DDSs) proposed in the scientific literature were here reviewed and classified according to the target pursued through the shape recovery process. Administration route, therapeutic goal, temporary and original shape, triggering stimulus, main innovation features and possible room for improvement of the DDSs were especially highlighted.

A Graphical Review on the Escalation of Fused Deposition Modeling (FDM) 3D Printing in the Pharmaceutical Field.

Fused deposition modeling 3D printing is currently one of the hot topics in pharmaceutics and has shown a 2000% increase in the number of research articles published in the last 5 years. In the prospect of a new era of fused deposition modeling focused on the industrial development of this technique applied to the fabrication of personalized medicines, a conceptual map to move through the evolution of the design of the printed dosage forms/drug delivery systems was conceived and mainly discussed by means of graphical tools.

Oral hydrophilic matrices having non uniform drug distribution for zero-order release: A literature review.

Oral hydrophilic matrices for prolonged release mostly show a decrease in the rate of drug release over time, owing to the increasing length of the diffusional path and progressive reduction of the area at the interface between glassy and rubbery matrix. In addition, burst effect may also occur due to the fraction of drug present on the surface of the system, which is released when the external polymer particles are not fully swollen yet. Different strategies have been attempted in order to address these issues and, ideally, to reach zero-order release. The approaches proposed are based on geometric modulation of the release area, control of the swelling behavior or initial non-uniform distribution of the active ingredient throughout the polymer matrix. The present article offers an extensive analysis of the various methods described in the literature for reaching zero-order release leveraging non-uniform distribution of the drug in hydrophilic polymeric systems. In this respect, special attention is given to the design of the main delivery platforms reviewed, their manufacturing, in vitro release profiles and analytical techniques for assessing drug concentration patterns within the solid units.

Evaluation of powder-layering vs. spray-coating techniques in the manufacturing of a swellable/erodible pulsatile delivery system.

A swellable/erodible system for oral time-dependent release, demonstrated to provide consistent pulsatile and colonic delivery performance, has been manufactured through a range of coating techniques to achieve the functional hydroxypropyl methylcellulose (HPMC) layer. Although aqueous spray-coating has long been preferred, the processing times and yields still represent open issues, especially in view of the considerable amount of polymer required to give in vivo lag phases of proper duration. To make manufacturing of the delivery system more cost-efficient, different coating modes were thus evaluated, namely top and tangential spray-coating as well as powder-layering, using a fluid bed equipment. To this aim, disintegrating tablets of 5 mm in diameter, containing a tracer drug, were coated up to 50% weight gain with low-viscosity HPMC, either as a water solution or as a powder formulation. In all cases, process feasibility was assessed following setup of the operating conditions. Irrespective of the technique employed, the resulting dosage forms exhibited uniform coating layers able to defer the onset of release as a function of the amount of polymer applied. The structure and thickness of such layers differed depending on the deposition modes. With respect to top spray-, both tangential spray-coating and powder-layering were shown to remarkably ameliorate the process time, which was reduced to approximately 1/3 and 1/6, and to enhance the yield by almost 20 and 30%, respectively. Clear advantages associated with such techniques were thus highlighted, particularly with respect to powder-layering here newly proposed for application of a swellable hydrophilic cellulose derivative.

Erodible coatings based on HPMC and cellulase for oral time-controlled release of drugs.

Oral drug delivery systems for time-controlled release, intended for chronotherapy or colon targeting, are often in the form of coated dosage forms provided with swellable/soluble hydrophilic polymer coatings. These are responsible for programmable lag phases prior to release, due to their progressive hydration in the biological fluids. When based on high-viscosity polymers and/or manufactured by press-coating, the performance of functional hydroxypropyl methylcellulose (HPMC) layers was not fully satisfactory. Particularly, it encompassed an initial phase of slow release because of outward diffusion of the drug through a persistent gel barrier surrounding the core. To promote erosion of such a barrier, the use of a cellulolytic product (Sternzym® C13030) was here explored. For this purpose, the mass loss behavior of tableted matrices based on various HPMC grades, containing increasing percentages of Sternzym® C13030, was preliminarily studied, highlighting a clear and concentration-dependent effect of the enzyme especially with high-viscosity polymers. Subsequently, Sternzym® C13030-containing systems, wherein the cellulolytic product was either incorporated into a high-viscosity HPMC coating or formed a separate underlying layer, were manufactured. Evaluated for release, such systems gave rise to more reproducible profiles, with shortened lag phases and reduced diffusional release, as compared to the reference formulation devoid of enzyme.

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.

Non-uniform drug distribution matrix system (NUDDMat) for zero-order release of drugs with different solubility.

A decrease in the drug release rate over time typically affects the performance of hydrophilic matrices for oral prolonged release. To address such an issue, a Non-Uniform Drug Distribution Matrix (NUDDMat) based on hypromellose was proposed and demonstrated to yield zero-order release. The system consisted of 5 overlaid layers, applied by powder layering, having drug concentration decreasing from the inside towards the outside of the matrix according to a descending staircase function. In the present study, manufacturing and performance of the described delivery platform were evaluated using drug tracers having different water solubility. Lansoprazole, acetaminophen and losartan potassium were selected as slightly (SST), moderately (MST) and highly (HST) soluble tracers. By halving the thickness of the external layer, which contained no drug, linear release of HST and MST was obtained. The release behavior of the NUDDMat system loaded with a drug having pH-independent solubility was shown to be consistent in pH 1.2, 4.5 and 6.8 media. Based on these results, feasibility of the NUDDMat platform by powder layering was demonstrated using drugs having different physico-technological characteristics. Moreover, its ability to generate zero-order release was proved in the case of drugs with water solubility in a relatively wide range.

3D printing by fused deposition modeling of single- and multi-compartment hollow systems for oral delivery - A review.

Feasibility of fused deposition modeling in 3D printing of hollow systems intended to convey different formulations for oral administration has recently been investigated. A major advantage of such printed devices is represented by the possibility of separately undertaking the development of the inner core from that of the outer shell, which could also act as a release-controlling barrier. Systems either composed of parts to be filled and assembled after fabrication or fabricated and filled in a single manufacturing process represent the main focus of this review. Devices having relatively simple (e.g. single-compartment capsule-like) configuration were first proposed followed by systems entailing multiple inner compartments. The latter were meant to be filled with different formulations, left empty for ensuring floatation or achieve combined release kinetics. For each of the reviewed systems, design, formulation approaches, manufacturing as well as release performance obtained were critically described. Versatility of FDM, especially in terms of geometric freedom provided, was highlighted together with some limitations that still need to be addressed, as expected for a newly-adopted fabrication technique that holds potential for being implemented in the pharmaceutical field.