Can in vitro/in silico tools improve colonic concentration estimations for oral extended-release formulations? A case study with upadacitinib

Upadacitinib, classified as a highly soluble drug, is commercially marketed as RINVOQ®, an modified-release formulation incorporating hydroxypropyl methylcellulose as a matrix system to target extended release throughout the gastrointestinal (GI) tract. Our study aimed to explore how drug release will occur throughout the GI tract using a plethora of in vitro and in silico tools. We built a Physiologically-Based Pharmacokinetic (PBPK) model in GastroPlus™ to predict the systemic concentrations of the drug when administered using in vitro dissolution profiles as input to drive luminal dissolution. A series of in vitro dissolution experiments were gathered using the USP Apparatus I, III and IV in presence of biorelevant media, simulating both fasted and fed state conditions. A key outcome from the current study was to establish an in vitro-in vivo correlation (IVIVC) between (i) the dissolution profiles obtained from the USP I, III and IV methods and (ii) the fraction absorbed of drug as deconvoluted from the plasma concentration-time profile of the drug. When linking the fraction dissolved as measured in the USP IV model, a Level A IVIVC was established. Moreover, when using the different dissolution profiles as input for PBPK modeling, it was also observed that predictions for plasma Cmax and AUC were most accurate for USP IV compared to the other models (based on predicted versus observed ratios). Furthermore, the PBPK model has the utility to extract the predicted concentrations at the level of the colon which can be of utmost interest when working with specific in vitro assays.

ROS-responsive nano-medicine for navigating autophagy to enhance targeted therapy of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic gastrointestinal disorder characterized by immune dysregulation and intestinal inflammation. Rapamycin (Ra), an mTORC1 pathway inhibitor, has shown promise for autophagy induction in IBD therapy but is associated with off-target effects and toxicity. To address these issues, we developed an oral liposome responsive to reactive oxygen species (ROS) using lipids and amphiphilic materials. We combined ketone thiol (TK) for ROS responsive and hyaluronic acid (HA) with high affinity for CD44 receptors to prepare rapamycin-loaded nanoparticle (Ra@TH). Owing to its ROS responsive characteristic, Ra@TH can achieve inflammatory colonic targeting. Additionally, Ra@TH can induce autophagy by inhibiting the mTORC1 pathway, leading to the clearance of damaged organelles, pathogenic microorganisms and oxidative stress products. Simultaneously, it also collaboratively inhibits the NF-κB pathway suppressed by the removal of ROS resulting from TK cleavage, thereby mediating the expression of inflammatory factors. Furthermore, Ra@TH enhances the expression of typical tight junction proteins, synergistically restoring intestinal barrier function. Our research not only expands the understanding of autophagy in IBD treatment but also introduces a promising therapeutic approach for IBD patients.

Colon-targeted delivery of polyphenols: construction principles, targeting mechanisms and evaluation methods

Polyphenols have received considerable attention for their promotive effects on colonic health. However, polyphenols are mostly sensitive to harsh gastrointestinal environments, thus, must be protected. It is necessary to design and develop a colon-targeted delivery system to improve the stability, colon-targeting and bioavailability of polyphenols. This paper mainly introduces research on colon-targeted controlled release of polyphenols. The physiological features affecting the dissolution, release and absorption of polyphenol-loaded delivery systems in the colon are first discussed. Simultaneously, the types of colon-targeted carriers with different release mechanisms are described, and colon-targeting assessment models that have been studied so far and their advantages and limitations are summarized. Based on the current research on polyphenols colon-targeting, outlook and reflections are proposed, with the goal of inspiring strategic development of new colon-targeted therapeutics to ensure that the polyphenols reach the colon with complete bioactivity.

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.

Colonic delivery of metronidazole-loaded capsules for local treatment of bacterial infections: A clinical pharmacoscintigraphy study

Drug delivery to the colon offers great promise for local treatment of colonic diseases as it allows bypassing systemic absorption in the small intestine, thereby increasing luminal drug concentrations in the colon. The primary objective of this in vivo pharmaco-scintigraphy study was to assess the colon drug targeting accuracy of a metronidazole benzoate colonic drug delivery system intended for local treatment of Clostridioides difficile infections. Additionally, it was assessed if the concept of mucoadhesion would increase colonic residence time and promote higher drug bioavailability. Two different capsule formulations were designed and tested in healthy human subjects. Capsules contained either non-mucoadhesive (NM) or mucoadhesive (M) microgranules, both loaded with 100 mg metronidazole benzoate (antibiotic prodrug) and 5 mg samarium oxide (scintigraphy tracer). Filled capsules were coated with a colonic-targeting technology consisting of two functional layers, which allow for accelerated drug release mediated by the intestinal pH in combination with colonic bacteria. Coated capsules were neutron-activated to yield the radioisotope ¹⁵³Sm prior to administration to 18 healthy subjects. Gamma-scintigraphy imaging was combined with the measurement of drug plasma levels. Formulation NM showed high colon-targeting accuracy. Initial capsule disintegration within the targeted ileocolonic region was observed in 8 out of 9 subjects (89%) with colonic arrival times in the range of 3.5-12 h and reduced systemic exposure. In contrast, the mucoadhesive formulation M showed some inconsistency regarding the site of initial capsule disintegration (targeting accuracy 56%). Variability of drug release was attributed to self-adhesion and agglomeration of the mucoadhesive microparticles within the capsule. Accurate ileocolonic delivery of metronidazole-loaded microgranules was achieved following oral administration of colonic-targeted capsules. Delayed drug release from NM microparticles in the colon leads to a reduced systemic exposure compared to immediate-release data from literature and presumably elevated drug concentrations in the colonic lumen. This approach offers promising options for the local treatment of colonic diseases.

Diclofenac-β-cyclodextrin for colonic drug targeting: In vivo performance in rats

The aim of this in vivo study was to assess the ability of the prodrug conjugate diclofenac-β-cyclodextrin to release diclofenac in the colon following oral administration, using sulfapyridine (a metabolite of sulfasalazine) as a marker of colonic absorption. Two groups of rats were used; the test rats received a suspension containing the two prodrugs, diclofenac-β-cyclodextrin and sulfasalazine, while the control rats received a suspension containing the corresponding free drugs, sodium diclofenac and sulfapyridine. The rats were fasted overnight with free access to water before and throughout the first 12h of the study. Blood was collected from the tail vein at pre-determined time points and the plasma analyzed for the concentrations of diclofenac and sulfapyridine. Following the oral administration of the two prodrugs, a more extended absorption profile was observed and Cmax was achieved 10h post-dose, in contrast to rapid absorption of the free drugs (tmax of diclofenac being 1.3h, and that of sulfapyridine being 2.1h). In addition to a later tmax, conjugation of diclofenac to β-cyclodextrin also resulted in a reduced Cmax and a reduced AUC. The same tmax for diclofenac-β-cyclodextrin as for sulfasalazine confirms the colonic metabolism of diclofenac-β-cyclodextrin. This study shows the potential of this new cyclodextrin-based prodrug to target and release diclofenac specifically in the colon following oral administration.