Gut reaction: impact of systemic diseases on gastrointestinal physiology and drug absorption

An overview on recent approaches for colonic drug delivery systems

Colon-targeted drug delivery systems have garnered significant interest as potential solutions for delivering various medications susceptible to acidic and catalytic degradation in the gastrointestinal (GI) tract or as a means of treating colonic diseases naturally with fewer overall side effects. The increasing demand for patient-friendly drug administration underscores the importance of colonic drug delivery, particularly through noninvasive methods like nanoparticulate drug delivery technologies. Such systems offer improved patient compliance, cost reduction, and therapeutic advantages. This study places particular emphasis on formulations and discusses recent advancements in various methods for designing colon-targeted drug delivery systems and their medicinal applications.

The Bioavailability of Drugs-The Current State of Knowledge

Drug bioavailability is a crucial aspect of pharmacology, affecting the effectiveness of drug therapy. Understanding how drugs are absorbed, distributed, metabolized, and eliminated in patients' bodies is essential to ensure proper and safe treatment. This publication aims to highlight the relevance of drug bioavailability research and its importance in therapy. In addition to biochemical activity, bioavailability also plays a critical role in achieving the desired therapeutic effects. This may seem obvious, but it is worth noting that a drug can only produce the expected effect if the proper level of concentration can be achieved at the desired point in a patient's body. Given the differences between patients, drug dosages, and administration forms, understanding and controlling bioavailability has become a priority in pharmacology. This publication discusses the basic concepts of bioavailability and the factors affecting it. We also looked at various methods of assessing bioavailability, both in the laboratory and in the clinic. Notably, the introduction of new technologies and tools in this field is vital to achieve advances in drug bioavailability research. This publication also discusses cases of drugs with poorly described bioavailability, providing a deeper understanding of the complex challenges they pose to medical researchers and practitioners. Simultaneously, the article focuses on the perspectives and trends that may shape the future of research regarding bioavailability, which is crucial to the development of modern pharmacology and drug therapy. In this context, the publication offers an essential, meaningful contribution toward understanding and highlighting bioavailability's role in reliable patient treatment. The text also identifies areas that require further research and exploration.

Impact of Disease States on the Oral Pharmacokinetics of EIDD-1931 (an Active Form of Molnupiravir) in Rats for Implication in the Dose Adjustment

The pharmacokinetic alteration of an antimicrobial medication leading to sub-therapeutic plasma level can aid in the emergence of resistance, a global threat nowadays. In this context, molnupiravir (prodrug of EIDD-1931) is the most efficacious orally against corona virus disease (COVID-19). In addition to drug-drug interaction, the pharmacokinetics of a drug can significantly vary during any disease state, leading to disease-drug interaction. However, no information is available for such a recently approved drug. Therefore, we aimed to explore the oral pharmacokinetics of EIDD-1931 in seven chemically induced disease states individually compared to the normal state using various rat models. Induction of any disease situation was confirmed by the disease specific study(s) prior to pharmacokinetic investigations. Compared to the normal state, substantially lowered plasma exposure (0.47- and 0.63-fold) with notably enhanced clearance (2.00- and 1.56-fold) of EIDD-1931 was observed in rats of ethanol-induced gastric injury and carbon tetrachloride-induced liver injury states. Conversely, paclitaxel-induced neuropathic pain and cisplatin-induced kidney injury states exhibited opposite outcomes on oral exposure (1.43- and 1.50-fold) and clearance (0.69- and 0.65-fold) of EIDD-1931. Although the highest plasma concentration (2.26-fold) markedly augmented in the doxorubicin-induced cardiac injury state, streptozocin-induced diabetes and lipopolysaccharide-induced lung injury state did not substantially influence the pharmacokinetics of EIDD-1931. Exploring the possible phenomenon behind the reduced or boosted plasma exposure of EIDD-1931, results suggest the need for dose adjustment in respective diseased conditions in order to achieve desired efficacy during oral therapy of EIDD-1931.

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.

Characterization of Aspirated Duodenal Fluids from Parkinson's Disease Patients

Parkinson's disease, one of the most common neurodegenerative diseases, may not only affect the motor system, but also the physiology of the gastrointestinal tract. Delayed gastric emptying, impaired motility and altered intestinal bacteria are well-established consequences of the disease, which can have a pronounced effect on the absorption of orally administered drugs. In contrast, no studies have been performed into the composition of intestinal fluids. It is not unlikely that Parkinson's disease also affects the composition of intestinal fluids, a critical factor in the in vitro and in silico simulation of drug dissolution, solubilization and absorption. In the current study, duodenal fluids were aspirated from Parkinson's disease (PD) patients and age-matched healthy controls (healthy controls, HC) consecutively in fasted and fed conditions. The fluids were then characterized for pH, buffer capacity, osmolality, total protein, phospholipids, bile salts, cholesterol and lipids. In a fasted state, the intestinal fluid composition was highly similar in PD patients and healthy controls. In general, the same was true for fed-state fluids, apart from a slightly slower and less pronounced initial change in factors directly affected by the meal (i.e., buffer capacity, osmolality, total protein and lipids) in PD patients. The absence of a fast initial increase for these factors immediately after meal intake, as was observed in healthy controls, might result from slower gastric emptying in PD patients. Irrespective of the prandial state, a higher relative amount of secondary bile salts was observed in PD patients, potentially indicating altered intestinal bacterial metabolism. Overall, the data from this study indicate that only minor disease-specific adjustments in small intestinal fluid composition should be considered when simulating intestinal drug absorption in PD patients.

Pharmacokinetics and tissue distribution of bleomycin-induced idiopathic pulmonary fibrosis rats treated with cryptotanshinone

Introduction: Cryptotanshinone(CTS), a compound derived from the root of Salvia miltiorrhiza, has been linked to various of diseases, particularly pulmonary fibrosis. In the current study, we investigated the benefit of CTS on Sprague-Dawley (SD) rats induced by bleomycin (BLM) and established high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) methods to compare pharmacokinetics and tissue distribution in subsequent normal and modulated SD rats.

Methods: The therapeutic effect of CTS on BLM-induced SD rats was evaluated using histopathology, lung function and hydroxyproline content measurement, revealing that CTS significantly improved SD rats induced by BLM. Additionally, a simple, rapid, sensitive and specific HPLC-MS/MS method was developed to determine the pharmacokinetics of various components in rat plasma.

Results: Pharmacokinetic studies indicated that CTS was slowly absorbed by oral administration and had low bioavailability and a slow clearance rate. The elimination of pulmonary fibrosis in 28-day rats was slowed down, and the area under the curve was increased compared to the control group. Long-term oral administration of CTS did not accumulate in vivo, but the clearance was slowed down, and the steady-state blood concentration was increased. The tissue distribution study revealed that CTS exposure in the lungs and liver.

Discussion: The lung CTS exposure was significantly higher in the model group than in the control group, suggesting that the pathological changes of pulmonary fibrosis were conducive to the lung exposure of CTS and served as the target organ of CTS.

Comparative Pharmacokinetic Study of 5 Active Ingredients after Oral Administration of Zuogui Pill in Osteoporotic Rats with Different Syndrome Types

Zuogui Pill is a kidney-yin-tonifying formula in traditional Chinese medicine that is widely used to manage osteoporosis with kidney-yin-deficiency in China. Herein, an efficient and accurate high-performance liquid chromatography-tandem mass spectrometry method was developed to determine the concentrations of 5 bioactive compounds in rat plasma following oral administration of Zuogui Pill. Because drug absorption and distribution differ under physiological and pathological conditions, the established method was used to quantify blood components and dynamic change in osteoporotic rats with different syndrome types. Moreover, integrated pharmacokinetic study was conducted to describe the overall pharmacokinetic characteristics of traditional Chinese medicine. The results showed that the absorption, distribution, and metabolism of Zuogui Pill varied widely under different states. The bioavailability of most active components showed significant advantages in osteoporotic rats with kidney-yin-deficiency, which corresponds to the opinion that Zuogui Pill has the effect of nourishing kidney-yin. It is hoped that this finding could interpret the pharmacodynamic substances and mechanism of Zuogui Pill in the treatment of osteoporosis with kidney-yin-deficiency.

Colonic drug delivery: Formulating the next generation of colon-targeted therapeutics

Colonic drug delivery can facilitate access to unique therapeutic targets and has the potential to enhance drug bioavailability whilst reducing off-target effects. Delivering drugs to the colon requires considered formulation development, as both oral and rectal dosage forms can encounter challenges if the colon's distinct physiological environment is not appreciated. As the therapeutic opportunities surrounding colonic drug delivery multiply, the success of novel pharmaceuticals lies in their design. This review provides a modern insight into the key parameters determining the effective design and development of colon-targeted medicines. Influential physiological features governing the release, dissolution, stability, and absorption of drugs in the colon are first discussed, followed by an overview of the most reliable colon-targeted formulation strategies. Finally, the most appropriate in vitro, in vivo, and in silico preclinical investigations are presented, with the goal of inspiring strategic development of new colon-targeted therapeutics.

Fast-Fed Variability: Insights into Drug Delivery, Molecular Manifestations, and Regulatory Aspects

Among various drug administration routes, oral drug delivery is preferred and is considered patient-friendly; hence, most of the marketed drugs are available as conventional tablets or capsules. In such cases, the administration of drugs with or without food has tremendous importance on the bioavailability of the drugs. The presence of food may increase (positive effect) or decrease (negative effect) the bioavailability of the drug. Such a positive or negative effect is undesirable since it makes dosage estimation difficult in several diseases. This may lead to an increased propensity for adverse effects of drugs when a positive food effect is perceived. However, a negative food effect may lead to therapeutic insufficiency for patients suffering from life-threatening disorders. This review emphasizes the causes of food effects, formulation strategies to overcome the fast-fed variability, and the regulatory aspects of drugs with food effects, which may open new avenues for researchers to design products that may help to eliminate fast-fed variability.

Computational modeling of drug dissolution in the human stomach: Effects of posture and gastroparesis on drug bioavailability

The oral route is the most common choice for drug administration because of several advantages, such as convenience, low cost, and high patient compliance, and the demand and investment in research and development for oral drugs continue to grow. The rate of dissolution and gastric emptying of the dissolved active pharmaceutical ingredient (API) into the duodenum is modulated by gastric motility, physical properties of the pill, and the contents of the stomach, but current in vitro procedures for assessing dissolution of oral drugs are limited in their ability to recapitulate this process. This is particularly relevant for disease conditions, such as gastroparesis, that alter the anatomy and/or physiology of the stomach. In silico models of gastric biomechanics offer the potential for overcoming these limitations of existing methods. In the current study, we employ a biomimetic in silico simulator based on the realistic anatomy and morphology of the stomach (referred to as "StomachSim") to investigate and quantify the effect of body posture and stomach motility on drug bioavailability. The simulations show that changes in posture can potentially have a significant (up to 83%) effect on the emptying rate of the API into the duodenum. Similarly, a reduction in antral contractility associated with gastroparesis can also be found to significantly reduce the dissolution of the pill as well as emptying of the API into the duodenum. The simulations show that for an equivalent motility index, the reduction in gastric emptying due to neuropathic gastroparesis is larger by a factor of about five compared to myopathic gastroparesis.

Comparative pharmacokinetic studies of five C-glycosylflavones in normal and urolithiasis model rats following administration of total flavonoids from Desmodium styracifolium by liquid chromatography-tandem mass spectrometry

The total flavonoids of Desmodium styracifolium are the flavonoid extracts purified from Desmodii Styracifolii Herba, which has conventionally been used for treating urolithiasis in China. In this study, a sensitive and simple liquid chromatography-tandem mass spectrometry method was developed to simultaneously determine five active components of the extracts in rat plasma. Chromatographic separation of the analytes (schaftoside, vicenin-1, vicenin-2, vicenin-3 and isovitexin) was performed on an ACQUITY UPLC HSS T3 Column under gradient elution conditions. The calibration curves were linear over ranges from 0.5 to 100 ng·mL^-1 for schaftoside, vicenin-1, vicenin-2, and vicenin-3, and 0.2 to 20 ng·mL^-1 for isovitexin. The RSD of intra- and inter-day precisions were ≤ 6.8% and ≤ 8.3%, respectively, and the accuracies (relative error) were within ±7.6%. The recoveries of the analytes ranged between 97.3 and 100.3%, and the matrix effects ranged from 98.6 to 113.8%. The method was successfully applied to the pharmacokinetic studies of the five active ingredients of Desmodium styracifolium, for the first time, in both normal and urolithiasis model rats. Results revealed that the plasma levels of these components were significantly increased under the pathological state. This study provided valuable information facilitating the clinical investigation of this medicine. This article is protected by copyright. All rights reserved.

Clinical translation of advanced colonic drug delivery technologies

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

HPLC-MS/MS based comparative pharmacokinetics of 12 bioactive components in normal and osteoporosis rats after oral administration of You-Gui-Wan

You-Gui-Wan is a traditional Chinese patent medicine that has been extensively used to treat kidney-yang deficiency syndrome. An HPLC-MS/MS method was developed to measure contents of 12 components of You-Gui-Wan in rat plasma. Considering that pathological changes might directly affect the pharmacokinetic behavior of drugs, this method was further applied to compare pharmacokinetics between normal and osteoporotic animals. The results indicated that osteoporosis significantly altered the pharmacokinetic characteristics of the 12 components. Thus, the pharmacokinetics of You-Gui-Wan evaluated under osteoporotic conditions were much closer to clinical practice than that in normal physiological states. Thus, the optimized analytical method, along with the pharmacokinetic evaluation in the osteoporotic model may offer a more comprehensive understanding to elucidate the anti-osteoporosis mechanism of You-Gui-Wan. These findings may aid in developing a more effective treatment plan for osteoporosis. This article is protected by copyright. All rights reserved.

Influence of probiotic bacteria on gut microbiota composition and gut wall function in an in-vitro model in patients with Parkinson's disease

We report here the potential role of a 4-strain probiotic suspension for use with patients with Parkinson's disease (PD). Stool samples from a group of three patients with diagnosed PD were used to create microbiotas in an in-vitro gut model. The effects of dosing with an oral probiotic suspension (Symprove) on bacterial composition and metabolic activity in the microbiotas was evaluated over 48 h and compared with healthy controls. Additionally, the effect of probiotic dosing on epithelial tight-junction integrity, production of inflammatory markers and wound healing were evaluated in cell culture models. In general, the relative proportions of the main bacterial phyla in the microbiotas of PD patients differed from those of healthy subjects, with levels of Firmicutes raised and levels of Bacteroidetes reduced. Dosing with probiotic resulted in a change in bacterial composition in the microbiotas over a 48 h period. Several other indicators of gut health changed upon dosing with the probiotic; production of short chain fatty acids (SCFAs) and lactate was stimulated, levels of anti-inflammatory cytokines (IL-6, IL-10) increased and levels of pro-inflammatory cytokines and chemokines (MCP-1 and IL-8) decreased. Tight junction integrity was seen to improve with probiotic dosing and wound healing was seen to occur faster than a control. The data suggest that if development and/or progression of PD is influenced by gut microbiota dysbiosis then supplementation of the diet with a properly formulated probiotic may be a useful adjunct to standard treatment in clinic.

Drug Screening, Oral Bioavailability and Regulatory Aspects: A Need for Human Organoids

The intestinal epithelium critically contributes to oral bioavailability of drugs by constituting an important site for drug absorption and metabolism. In particular, intestinal epithelial cells (IEC) actively serve as gatekeepers of drug and nutrient availability. IECs' transport processes and metabolism are interrelated to the whole-body metabolic state and represent potential points of origin as well as therapeutic targets for a variety of diseases. Human intestinal organoids represent a superior model of the intestinal epithelium, overcoming limitations of currently used in vitro models. Caco-2 cells or rodent explant models face drawbacks such as their cancer and non-human origin, respectively, but are commonly used to study intestinal nutrient absorption, enterocyte metabolism and oral drug bioavailability, despite poorly correlative data. In contrast, intestinal organoids allow investigating distinct aspects of bioavailability including spatial resolution of transport, inter-individual differences and high-throughput screenings. As several countries have already developed strategic roadmaps to phase out animal experiments for regulatory purposes, intestinal organoid culture and organ-on-a-chip technology in combination with in silico approaches are roads to go in the preclinical and regulatory setup and will aid implementing the 3Rs (reduction, refinement and replacement) principle in basic science.

Harnessing artificial intelligence for the next generation of 3D printed medicines

Artificial intelligence (AI) is redefining how we exist in the world. In almost every sector of society, AI is performing tasks with super-human speed and intellect; from the prediction of stock market trends to driverless vehicles, diagnosis of disease, and robotic surgery. Despite this growing success, the pharmaceutical field is yet to truly harness AI. Development and manufacture of medicines remains largely in a 'one size fits all' paradigm, in which mass-produced, identical formulations are expected to meet individual patient needs. Recently, 3D printing (3DP) has illuminated a path for on-demand production of fully customisable medicines. Due to its flexibility, pharmaceutical 3DP presents innumerable options during formulation development that generally require expert navigation. Leveraging AI within pharmaceutical 3DP removes the need for human expertise, as optimal process parameters can be accurately predicted by machine learning. AI can also be incorporated into a pharmaceutical 3DP 'Internet of Things', moving the personalised production of medicines into an intelligent, streamlined, and autonomous pipeline. Supportive infrastructure, such as The Cloud and blockchain, will also play a vital role. Crucially, these technologies will expedite the use of pharmaceutical 3DP in clinical settings and drive the global movement towards personalised medicine and Industry 4.0.

Predicting drug-microbiome interactions with machine learning

Pivotal work in recent years has cast light on the importance of the human microbiome in maintenance of health and physiological response to drugs. It is now clear that gastrointestinal microbiota have the metabolic power to promote, inactivate, or even toxify the efficacy of a drug to a level of clinically relevant significance. At the same time, it appears that drug intake has the propensity to alter gut microbiome composition, potentially affecting health and response to other drugs. Since the precise composition of an individual's microbiome is unique, one's drug-microbiome relationship is similarly unique. Thus, in the age of evermore personalised medicine, the ability to predict individuals' drug-microbiome interactions is highly sought. Machine learning (ML) offers a powerful toolkit capable of characterising and predicting drug-microbiota interactions at the individual patient level. ML techniques have the potential to learn the mechanisms operating drug-microbiome activities and measure patients' risk of such occurrences. This review will outline current knowledge at the drug-microbiota interface, and present ML as a technique for examining and forecasting personalised drug-microbiome interactions. When harnessed effectively, ML could alter how the pharmaceutical industry and healthcare professionals consider the drug-microbiome axis in patient care.

Potential Applications of Chitosan-Based Nanomaterials to Surpass the Gastrointestinal Physiological Obstacles and Enhance the Intestinal Drug Absorption

The small intestine provides the major site for the absorption of numerous orally administered drugs. However, before reaching to the systemic circulation to exert beneficial pharmacological activities, the oral drug delivery is hindered by poor absorption/metabolic instability of the drugs in gastrointestinal (GI) tract and the presence of the mucus layer overlying intestinal epithelium. Therefore, a polymeric drug delivery system has emerged as a robust approach to enhance oral drug bioavailability and intestinal drug absorption. Chitosan, a cationic polymer derived from chitin, and its derivatives have received remarkable attention to serve as a promising drug carrier, chiefly owing to their versatile, biocompatible, biodegradable, and non-toxic properties. Several types of chitosan-based drug delivery systems have been developed, including chemical modification, conjugates, capsules, and hybrids. They have been shown to be effective in improving intestinal assimilation of several types of drugs, e.g., antidiabetic, anticancer, antimicrobial, and anti-inflammatory drugs. In this review, the physiological challenges affecting intestinal drug absorption and the effects of chitosan on those parameters impacting on oral bioavailability are summarized. More appreciably, types of chitosan-based nanomaterials enhancing intestinal drug absorption and their mechanisms, as well as potential applications in diabetes, cancers, infections, and inflammation, are highlighted. The future perspective of chitosan applications is also discussed.

Current challenges and future perspectives in oral absorption research: An opinion of the UNGAP network

Although oral drug delivery is the preferred administration route and has been used for centuries, modern drug discovery and development pipelines challenge conventional formulation approaches and highlight the insufficient mechanistic understanding of processes critical to oral drug absorption. This review presents the opinion of UNGAP scientists on four key themes across the oral absorption landscape: (1) specific patient populations, (2) regional differences in the gastrointestinal tract, (3) advanced formulations and (4) food-drug interactions. The differences of oral absorption in pediatric and geriatric populations, the specific issues in colonic absorption, the formulation approaches for poorly water-soluble (small molecules) and poorly permeable (peptides, RNA etc.) drugs, as well as the vast realm of food effects, are some of the topics discussed in detail. The identified controversies and gaps in the current understanding of gastrointestinal absorption-related processes are used to create a roadmap for the future of oral drug absorption research.

Pharmacomagnetography to evaluate the performance of magnetic enteric-coated tablets in the human gastrointestinal tract

A magnetic enteric-coated tablet containing diclofenac sodium was produced, and its performance under physiological and disturbed gastrointestinal motility was assessed through pharmacomagnetography analysis. In vitro studies were performed using conventional methods and in vivo studies were conducted on healthy volunteers before (control) and after domperidone administration. The magnetic tablet's gastrointestinal (GI) transit and disintegration process were monitored using the Alternating Current Biosusceptometry sensors combined with drug plasmatic concentration. The Gastric Residence Time, Colon Arrival Time, Small Bowel Transit Time, Disintegration Time and the pharmacokinetics parameters were calculated. The pH-dependent polymers used to coat the magnetic tablets were able to avoid the premature drug release on gastric or small intestine simulated medium. Gastric Residence Time was accelerated compared with the control group (p < 0.01). No significant differences were found regarding small bowel transit, colon arrival, disintegration process, or pharmacokinetics parameters. A strong correlation between magnetic monitoring and pharmacokinetics parameters analysis was determinant to evaluate the efficiency in the drug delivery at a specific site in the human gastrointestinal tract. In addition, a tablet with a damaged coating was used as a proof of concept to show the suitability of our methodology to evaluate the tablet. Our study showed that pharmacomagnetography is a multi-instrumental approach towards assessing drug delivery and bioavailability.

Harnessing machine learning for development of microbiome therapeutics

The last twenty years of seminal microbiome research has uncovered microbiota's intrinsic relationship with human health. Studies elucidating the relationship between an unbalanced microbiome and disease are currently published daily. As such, microbiome big data have become a reality that provide a mine of information for the development of new therapeutics. Machine learning (ML), a branch of artificial intelligence, offers powerful techniques for big data analysis and prediction-making, that are out of reach of human intellect alone. This review will explore how ML can be applied for the development of microbiome-targeted therapeutics. A background on ML will be given, followed by a guide on where to find reliable microbiome big data. Existing applications and opportunities will be discussed, including the use of ML to discover, design, and characterize microbiome therapeutics. The use of ML to optimize advanced processes, such as 3D printing and in silico prediction of drug-microbiome interactions, will also be highlighted. Finally, barriers to adoption of ML in academic and industrial settings will be examined, concluded by a future outlook for the field.

McCoubrey L, Freire C, W. Basit A, Conlan RS, Gonzalez D. Progestogens Are Metabolized by the Gut Microbiota: Implications for Colonic Drug Delivery

Following oral administration, the bioavailability of progestogens is very low and highly variable, in part due to metabolism by cytochrome P450 enzymes found in the mucosa of the small intestine. Conversely, the mucosa in the colon contains much lower levels of cytochrome P450 enzymes, thus, colonic delivery of progestogens may be beneficial. Microbiota in the colon are known to metabolize a great number of drugs, therefore, it is important to understand the stability of these hormones in the presence of colonic flora before developing formulations. The aim of this study was to investigate the stability of three progestogens: progesterone, and its two synthetic analogues, medroxyprogesterone acetate (MPA) and levonorgestrel (LNG), in the presence of human colonic microbiota. Progesterone, MPA, and LNG were incubated in mixed fecal inoculum (simulated human colonic fluid) under anerobic conditions. Progesterone was completely degraded after 2 h, whereas levels of MPA and LNG were still detectable after 24 h. The half-lives of progesterone, MPA, and LNG in fecal inoculum were 28, 644, and 240 min, respectively. This study describes the kinetics of colonic microbial metabolism of these hormones for the first time. MPA and LNG show promise for delivery to the colon, potentially improving pharmacokinetics over current oral delivery methods.

The activities of drug inactive ingredients on biological targets

Excipients, considered "inactive ingredients," are a major component of formulated drugs and play key roles in their pharmacokinetics. Despite their pervasiveness, whether they are active on any targets has not been systematically explored. We computed the likelihood that approved excipients would bind to molecular targets. Testing in vitro revealed 25 excipient activities, ranging from low-nanomolar to high-micromolar concentration. Another 109 activities were identified by testing against clinical safety targets. In cellular models, five excipients had fingerprints predictive of system-level toxicity. Exposures of seven excipients were investigated, and in certain populations, two of these may reach levels of in vitro target potency, including brain and gut exposure of thimerosal and its major metabolite, which had dopamine D3 receptor dissociation constant K _d values of 320 and 210 nM, respectively. Although most excipients deserve their status as inert, many approved excipients may directly modulate physiologically relevant targets.

Gastrointestinal diseases and their impact on drug solubility: Crohn's disease

In order to investigate differences in drug solubilisation and dissolution in luminal fluids of Crohn's disease (CD) patients and healthy subjects, biorelevant media representative of CD patients were developed using information from literature and a Design of Experiment (DoE) approach. The CD media were characterised in terms of surface tension, osmolality, dynamic viscosity and buffer capacity and compared to healthy biorelevant media. To identify which drug characteristics are likely to present a high risk of altered drug solubility in CD, the solubility of six drugs was assessed in CD media and solubility differences were related to drug properties. Identified differences in CD patients compared to healthy subjects were a reduced concentration of bile salts, a higher gastric pH and a higher colonic osmolality. Differences in the properties of CD compared to healthy biorelevant media were mainly observed for surface tension and osmolality. Drug solubility of ionisable compounds was altered in gastric CD media compared to healthy biorelevant media. For drugs with moderate to high lipophilicity, a high risk of altered drug solubilisation in CD is expected, since a significant negative effect of log P and a positive effect of bile salts on drug solubility in colonic and fasted state intestinal CD media was observed. Simulating the conditions in CD patients in vitro offers the possibility to identify relevant differences in drug solubilisation without conducting expensive clinical trials.

Gastrointestinal diseases and their impact on drug solubility: Ulcerative Colitis

For poorly soluble compounds, drug product performance in patients with Ulcerative Colitis (UC) compared to healthy subjects can be affected due to differences in drug solubility in GI fluids. A risk assessment tool was developed to identify compounds with a high risk of altered solubility in the GI fluids of UC patients. Pathophysiological changes impacting on the composition of GI fluids in UC patients were considered and UC biorelevant media representative of the stomach, intestine and colon were developed based on biorelevant media based on healthy subjects and literature data using a Design of Experiment approach. The UC media were characterised and revealed differences in surface tension, osmolality and buffer capacity compared to media based on healthy subjects. The solubility of six drugs was investigated in UC biorelevant media and results were related to media- and drug-dependent factors. A lower drug solubility in UC intestinal media was observed for compounds with a high lipophilicity. In UC simulated colonic fluids, drug solubility was altered for ionisable compounds. Additionally, a higher solubility of neutral lipophilic drugs was observed in UC fasted state colonic media with increased concentrations of soluble proteins. The developed UC biorelevant media offer the possibility to identify the risk of altered drug solubilisation in UC patients without conducting expensive clinical trials. A high risk was related to drug ionization properties and lipophilicity in the current study with all investigated drugs showing differences in solubility in biorelevant media based on UC patients compared to healthy subjects.

Assessing the impact of cystic fibrosis on the antipyretic response of ibuprofen in children: Physiologically-based modeling as a candle in the dark

AIM

The goal of this study is to present the utility of quantitative modelling for extrapolation of drug safety and efficacy to underrepresented populations in controlled clinical trials. To illustrate this, the stepwise development of an integrated disease/pharmacokinetics/pharmacodynamics model of antipyretic efficacy of ibuprofen in children with cystic fibrosis (CF) is presented along with therapy optimization suggestions.

METHOD

Published clinical trials, in vitro data, and drug physiochemical properties were used to develop an ibuprofen-mediated antipyresis model for febrile children also having CF. Workflow included first developing a mechanistic absorption model using in vitro-in vivo extrapolation followed by physiologically-based pharmacokinetic (PBPK) modelling. The verified PBPK model was then scaled to paediatric patients with CF. Once verified, the PBPK model was linked to an indirect response model of antipyresis for simulation of the overall antipyretic efficacy of ibuprofen in CF children.

RESULTS

Model simulations showed therapeutic inequivalence between healthy children and paediatric patients with CF; C_max and AUC decreased by 39% (32-46%) and 44% (36-52%), respectively, in patients. Further, and in agreement with literature reports, predicted pharmacodynamics time courses suggest a slower onset and faster offset of action in patients compared to healthy children, 30 and 60 minutes, respectively. Exploratory simulations suggest an increase in dosing frequency for CF children as a better therapeutic strategy.

CONCLUSION

Model-informed approaches to leveraging knowledge obtained throughout the life cycle of drug development may play a key role in extrapolating drug efficacy and safety to underrepresented populations.

Advances in Oral Drug Delivery for Regional Targeting in the Gastrointestinal Tract - Influence of Physiological, Pathophysiological and Pharmaceutical Factors

The oral route is by far the most common route of drug administration in the gastrointestinal tract and can be used for both systemic drug delivery and for treating local gastrointestinal diseases. It is the most preferred route by patients, due to its advantages, such as ease of use, non-invasiveness, and convenience for self-administration. Formulations can also be designed to enhance drug delivery to specific regions in the upper or lower gastrointestinal tract. Despite the clear advantages offered by the oral route, drug delivery can be challenging as the human gastrointestinal tract is complex and displays a number of physiological barriers that affect drug delivery. Among these challenges are poor drug stability, poor drug solubility, and low drug permeability across the mucosal barriers. Attempts to overcome these issues have focused on improved understanding of the physiology of the gastrointestinal tract in both healthy and diseased states. Innovative pharmaceutical approaches have also been explored to improve regional drug targeting in the gastrointestinal tract, including nanoparticulate formulations. This review will discuss the physiological, pathophysiological, and pharmaceutical considerations influencing drug delivery for the oral route of administration, as well as the conventional and novel drug delivery approaches. The translational challenges and development aspects of novel formulations will also be addressed.

Physiological and Pharmaceutical Considerations for Rectal Drug Formulations

Although the oral route is the most convenient route for drug administration, there are a number of circumstances where this is not possible from either a clinical or pharmaceutical perspective. In these cases, the rectal route may represent a practical alternative and can be used to administer drugs for both local and systemic actions. The environment in the rectum is considered relatively constant and stable and has low enzymatic activity in comparison to other sections of the gastrointestinal tract. In addition, drugs can partially bypass the liver following systemic absorption, which reduces the hepatic first-pass effect. Therefore, rectal drug delivery can provide significant local and systemic levels for various drugs, despite the relatively small surface area of the rectal mucosa. Further development and optimization of rectal drug formulations have led to improvements in drug bioavailability, formulation retention, and drug release kinetics. However, despite the pharmaceutical advances in rectal drug delivery, very few of them have translated to the clinical phase. This review will address the physiological and pharmaceutical considerations influencing rectal drug delivery as well as the conventional and novel drug delivery approaches. The translational challenges and development aspects of novel formulations will also be discussed.

Application of Permeation Enhancers in Oral Delivery of Macromolecules: An Update

The application of permeation enhancers (PEs) to improve transport of poorly absorbed active pharmaceutical ingredients across the intestinal epithelium is a widely tested approach. Several hundred compounds have been shown to alter the epithelial barrier, and although the research emphasis has broadened to encompass a role for nanoparticle approaches, PEs represent a key constituent of conventional oral formulations that have progressed to clinical testing. In this review, we highlight promising PEs in early development, summarize the current state of the art, and highlight challenges to the translation of PE-based delivery systems into safe and effective oral dosage forms for patients.