A novel dissolution method relevant to intestinal release behaviour and its application in the evaluation of modified release mesalazine products

Harnessing therapeutic deep eutectic solvents in self-emulsifying systems to improve CBD delivery

In this study, Cannabidiol crystals (CBD) were used as a BCS class II model drug to generate a novel therapeutic deep eutectic solvent (THEDES) with easy preparation using caprylic acid (CA). The hydrogen bonding interaction was confirmed by different techniques such as FT-IR and NMR, resulting in a hydrophobic system suitable for liquid formulations. The CBD-based THEDES, combined with a specific mixture of surfactants and co-surfactants, successfully formed a self-emulsifying drug delivery system (SEDDS) that generated uniform nano-sized droplets once dispersed in water. Hence, the THEDES showed compatibility with the self-emulsifying approach, offering an alternative method to load drugs at their therapeutic dosage. Physical stability concerns regarding the unconventional oily phase were addressed through stress tests using multiple and dynamic light scattering, demonstrating the robustness of the system. In addition, the formulated SEDDS proved effective in protecting CBD from the harsh acidic gastric environment for up to 2 h at pH 1.2. Furthermore, in vitro studies have confirmed the safety of the formulation and the ability of CBD to permeate Caco-2 cells when formulated. This investigation highlights the potential incorporation of THEDES in lipid-based formulations like SEDDS, expanding the avenues for innovative oral drug delivery approaches.

Dual strategy to improve the oral bioavailability of efavirenz employing nanomicelles and curcumin as a bio-enhancer

The present investigation was focused on the development of Soluplus®-based nanomicelles (NMs) (10 % w/v) loaded with Efavirenz (EFV) (5 mg/mL) and Curcumin (natural bio-enhancer) (CUR) (5, 10 and 15 mg/mL) to improve the oral bioavalability of EFV. Micellar formulations were obtained employing an acetone-diffusion technique. Apparent aqueous solubility was increased up to ∼1250-fold and 25,000-fold for EFV and CUR, respectively. Drug-loaded nanoformulations showed an excellent colloidal stability with unimodal size distribution and PDI values < 0.30. In vitro drug release was 41.5 % (EFV) and 2.6 % (CUR) from EFV-CUR-NMs over 6 h in simulated gastrointestinal fluids. EFV-CUR-loaded NMs resulted as safe nanoformulations according to the in vitro cytocompatibility assays in Caco-2 cells. Furthermore, CUR bio-enhancer activity was demonstrated for those nanoformulations. A CUR concentration of 15 mg/mL produced a significant (p < 0.05) increment (2.64-fold) of relative EFV oral bioavailability. Finally, the active role of the lymphatic system in the absorption process of EFV, after its oral administration was assessed in a comparative pharmacokinetic study in presence and absence of cycloheximide, a lymphatic transport inhibitor. Overall our EFV-CUR-NMs denoted their potential as a novel nanotechnological platform, representing a step towards an optimized "nano-sized" therapy for AIDS patients.

Film Coatings Based on Aqueous Shellac Ammonium Salt "Swanlac® ASL 10" and Inulin for Colon Targeting

Over the past decades, increasing interests took place in the realm of drug delivery systems. Beyond treating intestinal diseases such as inflammatory bowel disease, colon targeting can provide possible applications for oral administration of proteins as well as vaccines due to the lower enzymatic activity in the distal part of GIT. To date, many strategies are employed to reach the colon. This article encompasses different biomaterials tested as film coatings and highlights appropriate formulations for colonic drug delivery. A comparison of different films was made to display the most interesting drug release profiles. These films contained ethylcellulose, as a thermoplastic polymer, blended with an aqueous shellac ammonium salt solution. Different blend ratios were selected as well for thin films as for coated mini-tablets, mainly varying as follows: (80:20); (75:25); (60:40). The impact of blend ratio and coating level was examined as well as the addition of natural polysaccharide "inulin" to target the colon. In vitro drug release was measured in 0.1 M HCl for 2 h followed by phosphate buffer saline pH 6.8 to simulate gastric and intestinal fluids, respectively. Coated mini-tablets were exposed to fresh fecal samples of humans in order to simulate roughly colonic content. Several formulations were able to fully protect theophylline as a model drug up to 8 h in the upper GIT, but allowing for prolonged release kinetics in the colon. These very interesting colonic release profiles were related to the amount of the natural polysaccharide added into the system.

Surface Engineering Methods for Powder Bed Printed Tablets to Optimize External Smoothness and Facilitate the Application of Different Coatings

In a previous attempt to achieve ileo-colonic targeting of bovine intestinal alkaline phosphatase (BIAP), we applied a pH-dependent coating, the ColoPulse coating, directly on powder bed printed (PBP) tablets. However, the high surface roughness necessitated an additional sub-coating layer [Nguyen, K. T. T., Pharmaceutics 2022]. In this study, we aimed to find a production method for PBP tablets containing BIAP that allows the direct application of coating systems. Alterations of the printing parameters, binder content, and printing layer height, when combined, were demonstrated to create visually less rough PBP tablets. The addition of ethanol vapor treatment further improved the surface's smoothness significantly. These changes enabled the direct application of the ColoPulse, or enteric coating, without a sub-coating. In vitro release testing showed the desired ileo-colonic release or upper-intestinal release for ColoPulse or enteric-coated tablets, respectively. Tablets containing BIAP, encapsulated within an inulin glass, maintained a high enzymatic activity (over 95%) even after 2 months of storage at 2-8 °C. Importantly, the coating process did not affect the activity of BIAP. In this study, we demonstrate, for the first time, the successful production of PBP tablets with surfaces that are directly coatable with the ColoPulse coating while preserving the stability of the encapsulated biopharmaceutical, BIAP.

Capsules with Ileocolonic-Targeted Release of Vitamin B2, B3, and C (ColoVit) Intended for Optimization of Gut Health: Development and Validation of the Production Process

The ileocolonic-targeted delivery of vitamins can establish beneficial alterations in gut microbial composition. Here, we describe the development of capsules containing riboflavin, nicotinic acid, and ascorbic acid covered with a pH-sensitive coating (ColoVit) to establish site-specific release in the ileocolon. Ingredient properties (particle size distribution, morphology) relevant for formulation and product quality were determined. Capsule content and the in vitro release behaviour were determined using a HPLC-method. Uncoated and coated validation batches were produced. Release characteristics were evaluated using a gastro-intestinal simulation system. All capsules met the required specifications. The contents of the ingredients were in the 90.0-120.0% range, and uniformity requirements were met. In the dissolution test a lag-time in drug release of 277-283 min was found, which meets requirements for ileocolonic release. The release itself is immediate as shown by dissolution of the vitamins of more than 75% in 1 h. The production process of the ColoVit formulation was validated and reproducible, it was shown that the vitamin blend was stable during the production process and in the finished coated product. The ColoVit is intended as an innovative treatment approach for beneficial microbiome modulation and optimization of gut health.

Form & formulation approaches for COntRollable Release in 3D printed Colonic Targeting (CORR3CT) budesonide tablet

Inflammatory bowel disease (IBD) represents a group of chronic and debilitating inflammatory diseases affecting various parts of the gastrointestinal (GI) tract. The disease incidence and prevalence have been growing worldwide since the early 21st century and this upward trend is expected to continue. Due to a complex and variable clinical presentation across different patients, the efficacy of a one-size-fits-all commercial formulation for IBD remains limited. Here, we present the development of a novel adjustable and controllable release, 3D printed colonic targeting (CORR3CT) dosage form of budesonide, to reduce off-targeting adverse effects and to potentially replace the use of enemas, which are invasive and commonly associated with poor adherence. An in vitro Gastrointestinal Simulated System (GISS) model was employed in this study to examine the ability of the 3D printed tablets to deliver budesonide to various targeted sites along the gastrointestinal tract. CORR3CT tablet with Pill-in-pill configurations were designed, fabricated and the relationship between the 3D printed design and resultant dissolution profiles were established. The 3D printed tablets also exhibited excellent and comparable dose accuracy and quality versus commercial tablets, while enhancing the delivery of budesonide to the targeted colon region. Overall, this study has laid the foundational proof of concept demonstrating controllable targeting of oral therapeutics along the gastrointestinal tract using 3D printing technologies.

3D Printed Fractal-like Structures with High Percentage of Drug for Zero-Order Colonic Release

Colonic drug delivery of drugs is an area of great interest due to the need to treat high prevalence colonic local diseases as well as systemic conditions that may benefit from the advantages associated to this route of drug administration. In the last decade, the use of 3D printing technologies has expanded, offering the possibility of preparing personalized medicines in small batches directly at the point of care. The aim of this work is to design a high drug loaded 3D printed system prepared by a combination of Fused Deposition Modelling (FDM) and Injection Volume Filling (IVF) techniques intended for zero-order colonic drug release. For this purpose, different batches of binary and ternary filaments based on the thermoplastic polyurethane Tecoflex EG-72D (TPU), theophylline anhydrous (AT) as model drug, and magnesium stearate as lubricant have been developed and characterized. Filaments with the highest drug load and the best rheological properties were selected for the manufacture of a printed fractal-like structure based on multiple toroids. This design was proposed to provide high surface area, leading to increased drug release and water uptake in the colonic region. This structure was 3D printed by FDM and then coated in a unique step by IVF technology using the enteric polymer DrugCoat S 12.5. This way, an additional coating process is avoided, reducing costs and production time. Studies of drug release confirmed the ability of the structures to provide a five-hour period of constant drug delivery in the colonic region.

Formulation of a 3D Printed Biopharmaceutical: The Development of an Alkaline Phosphatase Containing Tablet with Ileo-Colonic Release Profile to Treat Ulcerative Colitis

Powder bed printing is a 3D-printing process that creates freeform geometries from powders, with increasing traction for personalized medicine potential. Little is known about its applications for biopharmaceuticals. In this study, the production of tablets containing alkaline phosphatase using powder bed printing for the potential treatment of ulcerative colitis (UC) was investigated, as was the coating of these tablets to obtain ileo-colonic targeting. The printing process was studied, revealing line spacing as a critical factor affecting tablet physical properties when using hydroxypropyl cellulose as the binder. Increasing line spacing yielded tablets with higher porosity. The enzymatic activity of alkaline phosphatase (formulated in inulin glass) remained over 95% after 2 weeks of storage at 45 °C. The subsequent application of a colonic targeting coating required a PEG 1500 sub-coating. In vitro release experiments, using a gastrointestinal simulated system, indicated that the desired ileo-colonic release was achieved. Less than 8% of the methylene blue, a release marker, was released in the terminal ileum phase, followed by a fast release in the colon phase. No significant impact from the coating process on the enzymatic activity was found. These tablets are the first to achieve both biopharmaceutical incorporation in powder bed printed tablets and ileo-colonic targeting, thus might be suitable for on-demand patient-centric treatment of UC.

Formulation and In Vitro Evaluation of Pellets Containing Sulfasalazine and Caffeine to Verify Ileo-Colonic Drug Delivery

The ColoPulse coating is a pH-dependent coating that can be used to target drug release to the ileo-colonic region. ColoPulse coated tablets and capsules have demonstrated their targeting capabilities in vivo in more than 100 volunteers and patients. However, so far the ColoPulse coating has not been used for multi-particulate pellet formulations. The sulfasalazine-caffeine method can be used to confirm ileo-colonic drug delivery in vivo. Caffeine serves as a release marker in this method, while sulfasalazine serves as a marker for colonic arrival. In this study, extrusion-spheronization was used to produce microcrystalline cellulose based pellets containing both caffeine and sulfasalazine. Dissolution tests revealed that a superdisintegrant, i.e., croscarmellose sodium or sodium starch glycolate, should be incorporated in the formulation to achieve acceptable release profiles for both sulfasalazine and caffeine. However, acceptable release profiles were only obtained when the pelletizing liquid consisted of ethanol/water 1/1 (v/v) but not with pure water. This phenomenon was ascribed to the differences in the degree of swelling of the superdisintegrant in the pelletizing liquid during the granulation process. The pellets were coated with the ColoPulse coating and showed the desired pH-dependent pulsatile release profile in vitro. In future clinical studies, ileo-colonic targeting should be verified.

Budding Multi-matrix Technology-a Retrospective Approach, Deep Insights, and Future Perspectives

The human race is consistently striving for achieving good health and eliminate disease-causing factors. For the last few decades, scientists have been endeavoring to invent and innovate technologies that can substitute the conventional dosage forms and enable targeted and prolonged drug release at a particular site. The novel multi-matrix technology is a type of matrix formulation where the formulation is embraced to have a matrix system with multiple number of matrices. The MMX technology embraces with a combination of outer hydrophilic layer and amphiphilic/lipophilic core layer, within which drug is encapsulated followed by enteric coating for extended/targeted release at the required site. In comparison to conventional oral drug delivery systems and other drug delivery systems, multi-matrix (MMX) technology formulations afford many advantages. Additionally, it attributes for targeting strategy aimed at the colon and offers modified prolonged drug release. Thus, it has emerged rapidly as a potential alternative option in targeted oral drug delivery. However, the development of this MMX technology formulations is a exigent task and also has its own set of limitations. Due to its promising advantages and colon targeting strategy over the other colon targeted drug delivery systems, premier global companies are exploiting its potential. This article review deep insights into the formulation procedures, drug delivery mechanism, advantages, limitations, safety and efficacy studies of various marketed drug formulations of MMX technology including regulatory perspectives and future perspectives.

In vitro models to evaluate ingestible devices: Present status and current trends

Orally ingestible medical devices offer significant opportunity in the diagnosis and treatment of gastrointestinal conditions. Their development necessitates the use of models that simulate the gastrointestinal environment on both a macro and micro scale. An evolution in scientific technology has enabled a wide range of in vitro, ex vivo and in vivo models to be developed that replicate the gastrointestinal tract. This review describes the landscape of the existing range of in vitro tools that are available to characterize ingestible devices. Models are presented with details on their benefits and limitations with regards to the evaluation of ingestible devices and examples of their use in the evaluation of such devices is presented where available. The multitude of models available provides a suite of tools that can be used in the evaluation of ingestible devices that should be selected on the functionality of the device and the mechanism of its function.

3D printed systems for colon-specific delivery of camptothecin-loaded chitosan micelles

The use of 3D printing technology in the manufacturing of drug delivery systems has expanded and benefit of a customized care. The ability to create tailor-made structures filled with drugs/delivery systems with suitable drug dosage is especially appealing in the field of nanomedicine. In this work, chitosan-based polymeric micelles loaded with camptothecin (CPT) were incorporated into 3D printing systems (printfills) sealed with an enteric layer, aiming to protect the nanosystems from the harsh environment of the gastrointestinal tract (GIT). Polymeric micelles and printfills were fully characterized and, a simulated digestion of the 3D systems upon an oral administration was performed. The printfills maintained intact at the simulated gastric pH of the stomach and, only released the micelles at the colonic pH. From there, the dissolution media was used to recreate the intestinal absorption and, chitosan micelles showed a significant increase of the CPT permeability compared to the free drug, reaching an apparent permeability coefficient (P_app) of around 9×10^-6 cm/s in a 3D intestinal cell-based model. The combination of 3D printing with nanotechnology appears to have great potential for the colon-specific release of polymeric micelles, thereby increasing intestinal absorption while protecting the system/drug from degradation throughout the GIT.

Ileo-Colon Targeting of the Poorly Water-Soluble Drug Celecoxib Using a pH-Dependent Coating in Combination with Self-Emulsifying Drug Delivery or Solid Dispersion Systems

Targeting celecoxib to the ileo-colonic region could be beneficial for the treatment and prevention of colon cancer. Ileo-colonic targeting can be achieved by using pH-dependent coating systems such as ColoPulse. Celecoxib has poor aqueous solubility, which may jeopardize optimal treatment. Therefore, we combined a pH-dependent coating with self-emulsifying drug delivery systems (SEDDS) or with solid dispersion systems (SD); two approaches that are often used to improve the dissolution behavior of lipophilic drugs. The dissolution behavior of various formulations of both systems was investigated. Optimized formulations with and without precipitation inhibitors were coated with the ColoPulse and the release of celecoxib was tested under non-sink conditions using an in vitro dissolution system, simulating the pH gradient of the gastrointestinal tract. The dissolution behavior of SDs with and without precipitation inhibitor (sodium dodecyl sulfate) and the SEDDS without precipitation inhibitor was negatively impacted by the coating. Control experiments indicated that components of the coating released in the dissolution medium acted as precipitation mediators. However, the SEDDS formulation with HPMC 4000 cps as a precipitation inhibitor showed excellent dissolution behavior. We hypothesize that HPMC accumulates at the oil/water interface of the emulsion thereby stabilizing the emulsion resulting in maintenance of the supersaturated state.

Design, Synthesis and Studies on Novel Polymeric Prodrugs of Erlotinib for Colon Drug Delivery

AIMS

In the present study, polymer-drug conjugates were synthesized based on azo-bond cleavage drug delivery approach for targeting erlotinib as an anticancer drug specifically to the colon for the proficient treatment of colon cancer.

BACKGROUND

Colon Cancer (CC) is the third commonly detected tumor worldwide and makes up about 10% of all cases of cancers. Most of the chemotherapeutic drugs available for treating colon cancer are not only toxic to cancerous cells but also to the normal healthy cells. Among the various approaches to get rid of the adverse effects of anticancer agents, prodrugs are one of the most imperative approaches.

OBJECTIVE

The objective of the study is to chemically modify the erlotinib drug through azo-bond linkage and suitable spacer which will be finally linked to the polymeric backbone to give the desired polymer linked prodrug. The azo reductase enzyme present in the colon is supposed to cleave the azo-bond specifically and augment the drug release at the colon.

METHODS

The synthesized conjugates were characterized by IR and 1H-NMR spectroscopy. The cleavage of aromatic azo-bond resulted in a potential colon-specific liberation of drug from conjugate studied in rat fecal contents. In vitro release profiles of polyphosphazene-linked conjugates of erlotinib have been studied at pH 1.2, pH 6.8 and pH 7.4. The stability study was designed to exhibit that free drug was released proficiently and unmodified from polyphosphazene-erlotinib conjugates having aromatic azo-bond in artificial colon conditions.

RESULTS

The synthesized conjugates were demonstrated to be stable in simulated upper gastrointestinal tract conditions. The drug release kinetics shows that all the polymer-drug conjugates of erlotinib follow zero-order release kinetics which indicates that the drug release from the polymeric backbone is independent of its concentration. Kinetic study of conjugates with slope (n) shows the anomalous type of release with an exponent (n) > 0.89 indicating a super case II type of release.

CONCLUSION

These studies indicate that polyphosphazene linked drug conjugates of erlotinib could be promising candidates for the site-specific treatment of colon cancer with the least detrimental side-effects.

Artificial Neural Network (ANN) Approach to Predict an Optimized pH-Dependent Mesalamine Matrix Tablet

Background

Severe bleeding and perforation of the colon and rectum are complications of ulcerative colitis which can be treated by a targeted drug delivery system.

Purpose

Development of colon-targeted delivery usually involves a complex formulation process and coating steps of pH-sensitive methacrylic acid based Eudragit^®. The current work was purposefully designed to develop dicalcium phosphate (DCP) facilitated with Eudragit-S100-based pH-dependent, uncoated mesalamine matrix tablets.

Materials and Methods

Mesalamine formulations were compressed using wet granulation technique with varying compositions of dicalcium phosphate (DCP) and Eudragit-S100. The developed formulations were characterized for physicochemical and drug release profiles. Infrared studies were carried out to ensure that there was no interaction between active ingredients and excipients. Artificial neural network (ANN) was used for the optimization of final DCP-Eudragit-S100 complex and the experimental data were employed to train a multi-layer perception (MLP) using quick propagation (QP) training algorithm until a satisfactory root mean square error (RMSE) was reached. The ANN-aided optimized formulation was compared with commercially available Masacol^®.

Results

Compressed tablets met the desirability criteria in terms of thickness, hardness, weight variation, friability, and content uniformity, ie, 5.34 mm, 7.7 kg/cm^2, 585±5 mg (%), 0.44%, and 103%, respectively. In-vitro dissolution study of commercially available mesalamine and optimized formulation was carried out and the former showed 100% release at 6 h while the latter released only 12.09% after 2 h and 72.96% after 12 h which was fitted to Weibull release model with b value of 1.3, indicating a complex release mechanism.

Conclusion

DCP-Eudragit-S100 blend was found explicative for mesalamine release without coating in gastric and colonic regions. This combination may provide a better control of ulcerative colitis.

Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use:

https://youtu.be/AP32Kh16ZpU

pH-dependent ileocolonic drug delivery, part I: in vitro and clinical evaluation of novel systems

After the pH dependency of novel pH-dependent ileocolonic drug delivery systems is confirmed in vitro, their performance should be evaluated in human volunteers.

Towards the Oral Treatment of Ileo-Colonic Inflammatory Bowel Disease with Infliximab Tablets: Development and Validation of the Production Process

Infliximab (IFX) is an intravenously administered monoclonal antibody antagonizing the effects of tumor necrosis factor-alpha (TNF) systemically and is efficacious in the treatment of inflammatory bowel disease (IBD). However, studies suggest that the anti-inflammatory effects result from local immunomodulation in the inflamed regions. Furthermore, topical inhibition of TNF in IBD ameliorates inflammation. We therefore hypothesized that orally administered IFX targeted to the ileo-colonic region in IBD may be an efficacious new treatment option. This study describes the development and validation of the production process of ileo-colonic-targeted 5 mg IFX tablets (ColoPulse-IFX) intended for the oral treatment of IBD by means of producing three consecutive validation batches (VAL1, VAL2, and VAL3, respectively). UV-VIS spectroscopy, HPLC-SEC analysis (content, fragments, aggregates), fluorescence spectroscopy (tertiary protein structure), and ELISA (potency) showed no noticeable deviations of IFX compounded to ColoPulse-IFX compared to fresh IFX stock. The average ± SD (n = 10) IFX content of VAL1, VAL2, and VAL3 was 96 ± 2%, 97 ± 3%, and 96 ± 2%, respectively, and complied with the European Pharmacopeia (Ph. Eur.) requirements for Content Uniformity. The average ± SD (n = 3) ColoPulse-IFX potency was 105 ± 4%, 96 ± 4%, and 97 ± 5%, respectively, compared to fresh IFX stock. The IFX release profile from the tablet core was complete (≥85%) after 10 min in simulated ileum medium. The in vitro coating performance of ColoPulse-IFX showed that the formulation was targeted to the simulated ileo-colonic region. Stability data showed that ColoPulse-IFX was stable for up to 6 months stored at 25 °C/60% RH. Based on these results, the production process can be considered validated and its application is discussed in light of the rationale and available evidence for the topical treatment of IBD with IFX.

Nanostructured Chitosan-Based Biomaterials for Sustained and Colon-Specific Resveratrol Release

In the present work, we demonstrate the preparation of chitosan-based composites as vehicles of the natural occurring multi-drug resveratrol (RES). Such systems are endowed with potential therapeutic effects on inflammatory bowel diseases (IBD), such as Crohn's disease (CD) and ulcerative colitis, through the sustained colonic release of RES from long-lasting mucoadhesive drug depots. The loading of RES into nanoparticles (NPs) was optimized regarding two independent variables: RES/polymer ratio, and temperature. Twenty experiments were carried out and a Box⁻Behnken experimental design was used to evaluate the significance of these independent variables related to encapsulation efficiency (EE). The enhanced RES EE values were achieved in 24 h at 39 °C and at RES/polymer ratio of 0.75:1 w/w. Sizes and polydispersities of the optimized NPs were studied by dynamic light scattering (DLS). Chitosan (CTS) dispersions containing the RES-loaded NPs were ionically gelled with tricarballylic acid to yield CTS-NPs composites. Macro- and microscopic features (morphology and porosity studied by SEM and spreadability), thermal stability (studied by TGA), and release kinetics of the RES-loaded CTS-NPs were investigated. Release patterns in simulated colon conditions for 48 h displayed significant differences between the NPs (final cumulative drug release: 79⁻81%), and the CTS-NPs composites (29⁻34%).

Development of novel zero-order release budesonide tablets for the treatment of ileo-colonic inflammatory bowel disease and comparison with formulations currently used in clinical practice

Up to 50% of Crohn's disease and ulcerative colitis patients suffer from ileo-colonic inflammation. Topically delivered budesonide is an effective treatment but in vitro as well as clinical data suggest that oral formulations currently used in clinical practice are not optimal to treat the ileo-colon. The aim of this in vitro study was to develop ileo-colonic-targeted zero-order sustained-release tablets containing 3 mg or 9 mg budesonide. Targeted delivery was achieved by coating the tablets with the ColoPulse technology (ColoPulse 3 mg or ColoPulse 9 mg, respectively). Tablets were tested in a 10-h gastrointestinal simulation system for site-specific release, zero-order release kinetics (R² ≥ 0.950), release rate, and completeness of release (≥80%). Release profiles of the novel formulations were compared with Entocort, Budenofalk, and Cortiment (budesonide MMX). ColoPulse 3 mg and 9 mg were targeted to the simulated ileo-colon, budesonide release was complete and in a sustained zero-order manner, and both formulations complied with a 6-month accelerated stability study. None of the formulations currently used in clinical practice targeted the ileo-colon. These in vitro results are discussed in light of clinical data. ColoPulse 3 mg and 9 mg are novel interesting formulations for the treatment of the entire ileo-colon in inflammatory bowel disease.

A Novel Ileocolonic Release Peppermint Oil Capsule for Treatment of Irritable Bowel Syndrome: A Phase I Study in Healthy Volunteers

INTRODUCTION

Peppermint oil (PO) has been shown to reduce abdominal pain in patients with irritable bowel syndrome (IBS). PO is assumed to induce intestinal smooth muscle relaxation and desensitization of nociceptive nerve afferents. To increase colonic PO concentration, an ileocolonic release peppermint oil (IC-PO) capsule has been developed. The aim of this study was to compare pharmacokinetic parameters of the currently available small intestinal release PO (SI-PO) and the novel IC-PO.

METHODS

In this randomized, double-blind, crossover study, subjects received 182 mg of either SI-PO or IC-PO in a crossover design with a washout period of more than 14 days. Blood samples were collected to determine menthol glucuronide concentrations.

RESULTS

Eight healthy volunteers (50% female, median age 22) were included. The time to reach the maximum concentration (T_max) of IC-PO was significantly longer compared to SI-PO with a median (IQR) of 360 (360-405) versus 180 (120-180) min. The lag time (T_lag) was significantly longer with a median (IQR) of 225 (204-284) for IC-PO compared to 37 (6-65) min for SI-PO. The areas under the menthol glucuronide plasma concentration-time curves were significantly smaller with a median (IQR) of 2331 μg h/L (2006-2510) for IC-PO compared to 2623 μg h/L (2471-2920) for SI-PO. No significant differences were found in peak concentrations and elimination half-lives.

CONCLUSION

IC-PO has a significantly delayed peak menthol glucuronide concentration and T_lag, both pointing to the release of PO in the more distal part of the intestine. This may enhance therapeutic efficacy as it results in increased exposure of colonic mucosal afferents to the PO. A randomized controlled trial investigating the efficacy of SI and IC-PO in IBS is currently ongoing.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT02291445, EudraCT database 2014-004195-32.

Local delivery of macromolecules to treat diseases associated with the colon

Current treatments for intestinal diseases including inflammatory bowel diseases, irritable bowel syndrome, and colonic bacterial infections are typically small molecule oral dosage forms designed for systemic delivery. The intestinal permeability hurdle to achieve systemic delivery from oral formulations of macromolecules is challenging, but this drawback can be advantageous if an intestinal region is associated with the disease. There are some promising formulation approaches to release peptides, proteins, antibodies, antisense oligonucleotides, RNA, and probiotics in the colon to enable local delivery and efficacy. We briefly review colonic physiology in relation to the main colon-associated diseases (inflammatory bowel disease, irritable bowel syndrome, infection, and colorectal cancer), along with the impact of colon physiology on dosage form design of macromolecules. We then assess formulation strategies designed to achieve colonic delivery of small molecules and concluded that they can also be applied some extent to macromolecules. We describe examples of formulation strategies in preclinical research aimed at colonic delivery of macromolecules to achieve high local concentration in the lumen, epithelial-, or sub-epithelial tissue, depending on the target, but with the benefit of reduced systemic exposure and toxicity. Finally, the industrial challenges in developing macromolecule formulations for colon-associated diseases are presented, along with a framework for selecting appropriate delivery technologies.

Impact of gastrointestinal disease states on oral drug absorption – implications for formulation design – a PEARRL review

Objectives

Drug product performance in patients with gastrointestinal (GI) diseases can be altered compared to healthy subjects due to pathophysiological changes. In this review, relevant differences in patients with inflammatory bowel diseases, coeliac disease, irritable bowel syndrome and short bowel syndrome are discussed and possible in vitro and in silico tools to predict drug product performance in this patient population are assessed.

Key findings

Drug product performance was altered in patients with GI diseases compared to healthy subjects, as assessed in a limited number of studies for some drugs. Underlying causes can be observed pathophysiological alterations such as the differences in GI transit time, the composition of the GI fluids and GI permeability. Additionally, alterations in the abundance of metabolising enzymes and transporter systems were observed. The effect of the GI diseases on each parameter is not always evident as it may depend on the location and the state of the disease. The impact of the pathophysiological change on drug bioavailability depends on the physicochemical characteristics of the drug, the pharmaceutical formulation and drug metabolism. In vitro and in silico methods to predict drug product performance in patients with GI diseases are currently limited but could be a useful tool to improve drug therapy.

Summary

Development of suitable in vitro dissolution and in silico models for patients with GI diseases can improve their drug therapy. The likeliness of the models to provide accurate predictions depends on the knowledge of pathophysiological alterations, and thus, further assessment of physiological differences is essential.

A gastrointestinal simulation system for dissolution of oral solid dosage forms before and after Roux-en-Y gastric bypass

Background

The Roux-en-Y gastric bypass (RYGB) is a bariatric procedure, greatly reducing the stomach size and bypassing the duodenum and proximal jejunum. Hence, RYGB may reduce the absorption and bioavailability of oral medication. For clinical decisions on the use of medication, knowledge of altered modifications in drug disposition is a prerequisite. An in vitro dissolution method for solid oral medications, simulating conditions before and after RYGB, might be a valuable tool to predict the pharmaceutical availability of medicines frequently used by patients after RYGB.

Objectives

To develop a gastrointestinal simulation system (GISS), mimicking conditions before and after RYGB for investigating dissolution characteristics of solid oral medications, and to assess the pharmaceutical availability of metoprolol from immediate-release (IR) and controlled-release (CR) tablets under these conditions.

Methods

With an adjusted, pharmacopoeial paddle dissolution apparatus, the GISS enables variation in parameters which are relevant to drug release in vivo: pH, volume, residence time, osmolality and agitation. Metoprolol tartrate 100 mg IR tablets and metoprolol CR tablets were tested. Release profiles were determined by measuring the concentrations of metoprolol spectrophotometrically.

Results

From IR tablets, under all conditions applied, >85% of metoprolol was released within 25 min. From all tested CR tablets >90% of metoprolol was released after 22 hours.

Conclusions

This GISS is a suitable dissolution system to assess pharmaceutical availability before and after RYGB. In patients who have undergone RYGB, no problems in pharmaceutical availability of metoprolol IR and CR tablets are to be expected. Any changes in response to metoprolol in patients after RYGB should therefore be ascribed to changes in bioavailability.

Development of a zero-order sustained-release tablet containing mesalazine and budesonide intended to treat the distal gastrointestinal tract in inflammatory bowel disease

Ulcerative colitis (UC) and Crohn's disease (CD) are diseases affecting the gastrointestinal tract. Treatment depends on the severity of the disease, site of inflammation, and patient's response. The aim of this study was to develop a zero-order sustained-release tablet containing both the anti-inflammatory drugs mesalazine and budesonide as a new treatment option for ileo-colonic CD and UC. Tablets were attained by wet granulation with hydroxypropyl methylcellulose and direct compression. Our newly developed tablet core was coated with different ColoPulse® coating thicknesses and the mesalazine and budesonide release profiles were investigated in a 600-min gastrointestinal simulation system (GISS) experiment, together with commercially available MMX®-mesalazine and MMX®-budesonide. Lag-time, release rate (k0), completeness of release, and zero-order correlation coefficient (R(2)0) could be manipulated by varying ColoPulse® coating thickness. Our newly developed combination preparation (C[4.92]) complied with all conducted European Pharmacopoeia tests as well as an accelerated 6-month stability test and had a lag-time of 250min (simulated ileum targeted), a linear release profile (mesalazine R(2)0=0.9002; budesonide R(2)0=0.9481), and drug release of 100% mesalazine and 77% budesonide. Like C[4.92], MMX®-mesalazine had a linear (R(2)0=0.9883) and complete release profile (96%). However, C[4.92] lag-time was longer (250 vs. 210min), assuring simulated ileum specificity. Remarkably, MMX®-budesonide lag-time was 480min and release was only 7% with a linear character (R(2)0=0.9906). The in vitro results suggest that MMX®-budesonide effectiveness may be improved if budesonide release in the aqueous phase would be increased and that C[4.92] is a potential, new treatment option for ileo-colonic CD and UC.

Gastrointestinal pH and Transit Time Profiling in Healthy Volunteers Using the IntelliCap System Confirms Ileo-Colonic Release of ColoPulse Tablets

INTRODUCTION

ColoPulse tablets are an innovative development in the field of oral dosage forms characterized by a distal ileum and colon-specific release. Previous studies in humans showed release in the ileo-colonic region, but the relationship between gastrointestinal pH and release was not experimentally proven in vivo. This information will complete the in vivo release-profile of ColoPulse tablets.

MATERIALS AND METHODS

Release from ColoPulse tablets was studied in 16 healthy volunteers using the dual label isotope strategy. To determine gastrointestinal pH profiles and transit times the IntelliCap system was used. A ColoPulse tablet containing 13C-urea and an uncoated, immediate release tablet containing 15N2-urea were taken simultaneously followed by a standardized breakfast after three hours. Five minutes after intake of the tablets the IntelliCap capsule was swallowed and pH was measured until excretion in the feces. Breath and urine samples were collected for isotope analysis.

RESULTS

Full analysis could be performed in 12 subjects. Median bioavailability of 13C -urea was 82% (95% CI 74-94%, range 61-114%). The median lag time (5% release of 13C) was 5:42 h (95% CI 5:18-6:18 h, range 2:36-6:36 h,) There was no statistically significant difference between lag time based on isotope signal and colon arrival time (CAT) based on pH (median 5:42 vs 5:31 h p = 0.903). In all subjects an intestinal pH value of 7.0 was reached before release of 13C from the ColoPulse tablet occurred.

DISCUSSION AND CONCLUSIONS

From the combined data from the IntelliCap system and the 13C -isotope signal it can be concluded that release from a ColoPulse tablet in vivo is not related to transit times but occurs in the ileo-colonic region after pH 7.0 is reached. This supports our earlier findings and confirms that the ColoPulse system is a promising delivery system for targeting the distal ileum and colon.

TRIAL REGISTRATION

ISRCTN Registry 18301880.

Design, synthesis and ex-vivo release studies of colon-specific polyphosphazene-anticancer drug conjugates

Colon-specific azo based polyphosphazene-anticancer drug conjugates (11-18) have been synthesized and evaluated by ex-vivo release studies. The prepared polyphosphazene drug conjugates (11-18) are stable in acidic (pH=1.2) buffer which showed that these polymer drug conjugates are protected from acidic environment which is the primary requirement of colon specific targeted drug delivery. The ex-vivo release profiles of polyphosphazene drug conjugates (11-18) have been performed in the presence as well as in the absence of rat cecal content. The results showed that more than 89% of parent drugs (methotrexate and gemcitabine) are released from polymeric backbone of polyphosphazene drug conjugates (14 and 18) having n-butanol (lipophilic moiety). The in-vitro cytotoxicity assay has also been performed which clearly indicated that these polymeric drug conjugates are active against human colorectal cancer cell lines (HT-29 and COLO 320 DM). The drug release kinetic study demonstrated that Higuchi's equation is found to be best fitted equation which showed that release of drug from polymeric backbone as square root of time dependent process based on non-fickian diffusion. Therefore, the synthesized polyphosphazene azo based drug conjugates of methotrexate and gemcitabine are the potential candidates for colon targeted drug delivery system with minimal undesirable side effects.

ColoPulse tablets perform comparably in healthy volunteers and Crohn's patients and show no influence of food and time of food intake on bioavailability

ColoPulse tablets are an innovative development in the field of oral drug delivery and are characterized by a colon-specific release. Until now ColoPulse dosage forms (only capsules) have been studied in healthy volunteers having a standardized breakfast three hours after administration but not in specific patient groups and not with a shorter interval between administration and breakfast. Information on bioavailability and release characteristics of ColoPulse tablets in Crohn's patients and the influence of food and time of food intake is a prerequisite to properly design future clinical studies with active substances in these patients. In the current cross-over study bioavailability and drug release characteristics of ColoPulse tablets were compared in healthy volunteers and in Crohn's patients in remission. Furthermore the influence of food and time of food intake on the in vivo drug release behavior of ColoPulse tablets was investigated. In this study the dual label isotope strategy was used which means that a ColoPulse tablet containing (13)C-urea and an uncoated, immediate release tablet containing (15)N2-urea were taken simultaneously. Breath and urine samples were collected during the test day for isotope analysis. The appearance of the stable isotopes in breath and/or urine provides information on the site of release from the dosage form, release characteristics and bioavailability. Both tablets were administered on two different days in a cross-over design: the first day with a breakfast (non-standardized) one hour after administration and the second day with a standardized breakfast three hours after administration of the tablets. There was no difference in instructions for administration between both days. Results of 16 healthy volunteers and 14 Crohn's patients were evaluated. At least 86% (51 out of 59) of all ColoPulse tablets administered in this study released their contents at the desired intestinal region. There was no significant difference in bioavailability between healthy volunteers and Crohn's patients on both days (day 1 75.8% vs 90.2%, p=0.070 and day 2 83.4% vs 91.4%, p=0.265). There was also no significant influence of food and time of food intake on bioavailability in healthy volunteers (75.8% and 83.4%, p=0.077) and in Crohn's patients (90.2% and 91.4%, p=0.618) when day 1 and day 2 were compared. Release characteristics did not significantly differ between healthy volunteers and Crohn's patients. However, food and time of food intake had some, clinically non-relevant, influence on the release characteristics within both groups which is in line with the fact that food affects gastro-intestinal transit times. This study shows that ColoPulse tablets enable the site-specific delivery of drugs or other compounds (e.g. diagnostics) deep in the ileo-colonic region of the intestine of Crohn's patients in a comparable amount and rate as in healthy volunteers. Food and time of food intake had no relevant influence on bioavailability. In conclusion ColoPulse delivery systems are promising and deserve further research for local therapy with immunosuppressive drugs in Crohn's patients in the near future.

Design, synthesis and ex vivo evaluation of colon-specific azo based prodrugs of anticancer agents

Colon-specific azo based prodrugs of anticancer agents like methotrexate (6), gemcitabine (7) and analogue of oxaliplatin (RTB-4) (8) were synthesized and characterized by modern analytical techniques. The prepared prodrugs were stable in acidic (pH 1.2) and basic (pH 7.4) buffers which showed their stability in upper GIT environment. Further, an assay was performed which demonstrated the presence of azoreductase enzyme in the rat fecal material, rat cecum content and other parts of intestinal content which reduce specifically the azo bond and release the drug. The in vitro cytotoxicity assay was also performed which clearly indicated that these azo based prodrugs are active against human colorectal cancer cell lines (COLO 205, COLO 320 DM and HT-29). The release behavior of prodrugs (10, 11 and 15) was 60-70% after 24h incubation at 37°C. Therefore, the synthesized azo linked prodrugs of methotrexate, gemcitabine and RTB-4 are the potential candidates for colon targeted drug delivery system with minimal undesirable side effects.

Isotope-labelled urea to test colon drug delivery devices in vivo: principles, calculations and interpretations

This paper describes various methodological aspects that were encountered during the development of a system to monitor the in vivo behaviour of a newly developed colon delivery device that enables oral drug treatment of inflammatory bowel diseases. [(13)C]urea was chosen as the marker substance. Release of [(13)C]urea in the ileocolonic region is proven by the exhalation of (13)CO2 in breath due to bacterial fermentation of [(13)C]urea. The (13)CO2 exhalation kinetics allows the calculation of a lag time as marker for delay of release, a pulse time as marker for the speed of drug release and the fraction of the dose that is fermented. To determine the total bioavailability, also the fraction of the dose absorbed from the intestine must be quantified. Initially, this was done by calculating the time-dependent [(13)C]urea appearance in the body urea pool via measurement of (13)C abundance and concentration of plasma urea. Thereafter, a new methodology was successfully developed to obtain the bioavailability data by measurement of the urinary excretion rate of [(13)C]urea. These techniques required two experimental days, one to test the coated device, another to test the uncoated device to obtain reference values for the situation that 100 % of [(13)C]urea is absorbed. This is hampered by large day-to-day variations in urea metabolism. Finally, a completely non-invasive, one-day test was worked out based on a dual isotope approach applying a simultaneous administration of [(13)C]urea in a coated device and [(15)N2]urea in an uncoated device. All aspects of isotope-related analytical methodologies and required calculation and correction systems are described.

Dissolution testing of oral modified-release dosage forms

Objectives

The in-vivo performance of oral modified-release dosage forms is determined by the interplay of various physiological- and dosage-form-derived parameters. Thus it is often a challenge to predict the in-vivo drug-release behaviour from modified-release dosage forms based solely on in-vitro release rates.

Key findings

For a long time the most common procedure to obtain in-vitro/in-vivo correlations for modified-release formulations was to apply test conditions typically used for quality control on a retrospective basis. Such so-called ‘compendial approaches’ are typically not biorelevant with respect to volumes, composition and physicochemical properties of the test media and also do not take into consideration the mechanical and hydrodynamic forces that may influence dosage-form behaviour during passage through the gastrointestinal tract.

Summary

This review provides an overview of physiological conditions relevant to in-vivo drug release and of dissolution models which, based on current scientific findings on human gastrointestinal physiology, have been developed to enable a better prediction of the in-vivo performance of oral MR dosage forms.

Film coated tablets (ColoPulse technology) for targeted delivery in the lower intestinal tract: influence of the core composition on release characteristics

The design of a film coating technology which allows a tablet to deliver the drug in the ileocolonic segment would offer new treatment possibilities. The objective is to develop a platform technology that is suitable for a broad range of drug compounds. We developed a coated tablet with a delayed, pulsatile release profile based on a pH-sensitive coating technology (ColoPulse). The production process was validated, and the effect of core composition on the in vitro release and water uptake investigated. The release profile of the standard tablet core composition, based on the use of cellulose as a filler, was independent of the coat thickness in a range of 9.0-13.2 mg/cm(2). The release profile of a coated tablet was strongly influenced when cellulose was partly replaced by the model substance glucose (loss of sigmoidal release), citric acid (stabilization), sodium bicarbonate (destabilization) or sodium benzoate (destabilization). The film coating takes up water when below the pH-threshold. However, this did not cause early disintegration of the coating. The ColoPulse technology is successfully applied on tablets. The in vitro release characteristics of the coated tablets are influenced by the composition of the core.

Review article: 5-aminosalicylate formulations for the treatment of ulcerative colitis--methods of comparing release rates and delivery of 5-aminosalicylate to the colonic mucosa

BACKGROUND

Many oral 5-aminosalicylic acid (5-ASA) formulations are designed to maximize 5-ASA release in the colon where it acts topically on the colonic mucosa. Delayed-release formulations and azo-prodrugs minimize 5-ASA absorption in the upper gastrointestinal (GI) tract.

AIMS

To review methods for assessing 5-ASA release and colonic distribution from oral formulations, and the potential use of this information for guiding clinical decisions.

METHODS

PubMed and recent conference abstracts were searched for articles describing techniques used to assess 5-ASA release from ulcerative colitis (UC) therapies.

RESULTS

In-vitro GI models, although unable to simulate more complex aspects of GI physiology, can provide useful data on 5-ASA release kinetics and bioaccessibility. Gamma-scintigraphy is useful for investigating GI disintegration of different formulations, but may not accurately reflect 5-ASA distribution. Plasma pharmacokinetic studies provide data on systemic exposure, but not on colonic distribution or mucosal uptake. Mucosal biopsies provide direct evidence of colonic distribution and may predict clinical efficacy, but must be interpreted cautiously because of considerable inter-subject variability and other confounding factors.

CONCLUSION

While assessment of 5-ASA release is important, limitations of individual measurement techniques mean that randomized clinical studies in UC patients remain the best guide for dosing and treatment regimen decisions.

Towards an oral influenza vaccine: comparison between intragastric and intracolonic delivery of influenza subunit vaccine in a murine model

In this paper we investigated to which part of the gastro-intestinal (GI) tract, the upper or lower part, an oral influenza vaccine should be targeted to result in an effective immune response in mice. Our study demonstrates that without adjuvant substantial systemic but low respiratory mucosal immune responses were induced in mice after delivery of influenza subunit vaccine to the upper GI-tract (intragastric) as well as the lower GI-tract (intracolonically). When the vaccine was adjuvanted with Escherichia coli heat-labile enterotoxin (LT) these responses were significantly enhanced. Interestingly, intracolonic administration of vaccine with adjuvant also resulted in enhanced cellular immune responses and the desired Th1-skewing of these responses. Intragastric administration of the adjuvanted vaccine also increased T-helper responses. However, Th1-skewing was absent. In conclusion, the right combination of strong mucosal adjuvant (e.g. LT) and antigen delivery site (e.g. the lower part of the gastro-intestinal tract) might result in effective vaccination via the oral route.