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The mechanism of action of excipients eliciting sex differences in drug bioavailability is poorly understood. In this study, the excipients Cremophor RH 40 (PEG 40 hydrogenated castor oil), Poloxamer 188 (2-methyloxirane) and Tween 80 (polyoxyethylene (80) sorbitan monooleate) were screened at 0.07 - 5% concentrations for their effect on ranitidine bioavailability in male and female Wistar rats. We show that all excipient concentrations significantly increased ranitidine bioavailability in male, but not female, rats. The effect of these excipients on the intestinal efflux transporters P-glycoprotein (P-gp), breast cancer resistant protein (BCRP) and multi-drug resistant protein 2 (MRP2) were also monitored. Measured by ELISA assay, in male rats, peak reductions in intestinal P-gp protein expression occurred in the presence of 1% Cremophor RH 40 and Poloxamer 188 and 0.5% Tween 80. In contrast, no distinct changes were observed in female intestinal P-gp expression. Unlike P-gp, all excipients had a positive effect on MRP2 protein expression - albeit only in males - in a concentration-dependent manner. The excipients did not modulate intestinal BCRP protein expression in either sex. Endogenous hormones and a nuclear receptor (testosterone, oestradiol and pregnane X receptor; PXR) that are purported to regulate intestinal efflux membrane transporter expression were also quantified. In the presence of all excipients, testosterone levels significantly elevated in males, although PXR levels reduced at similar rates in both sexes. No significant effects were identified in oestradiol levels in male and female rats. It is clear that excipients are not inert and their pathway for modulating drug response is multi-dimensional and specific between sexes. This study showed that excipients increased drug bioavailability of a P-gp drug substrate due to its reductive effect on intestinal P-gp expression; we propose that this link may be due to the excipients modulating fundamental testosterone levels. Understanding the implication of excipients on intestinal physiology and hormone levels can therefore improve pharmaceutical design, clinical efficacy and instigate next generation personalised, sex-specific formulations.

Intestinal efflux transporters affect the gastrointestinal processing of many drugs but further data on their intestinal expression levels are required. Relative mRNA expression and relative and absolute protein expression data of transporters are commonly measured by real-time polymerase chain reaction (RT-PCR), Western blot and mass spectrometry-based targeted proteomics techniques. All of these methods, however, have their own strengths and limitations, and therefore, validation for optimized quantification methods is needed. As such, the identification of the most appropriate technique is necessary to effectively translate preclinical findings to first-in-human trials. In this study, the mRNA expression and protein levels of the efflux transporter P-glycoprotein (P-gp) in jejunal and ileal epithelia of 30 male and female human subjects, and the duodenal, jejunal, ileal and colonic tissues in 48 Wistar rats were quantified using RT-PCR, Western blot and liquid chromatography-tandem mass spectrometry (LC-MS/MS). A similar sex difference was observed in the expression of small intestinal P-gp in humans and Wistar rats where P-gp was higher in males than females with an increasing trend from the proximal to the distal parts in both species. A strong positive linear correlation was determined between the Western blot data and LC-MS/MS data in the small intestine of humans (R2 = 0.85). Conflicting results, however, were shown in rat small intestinal and colonic P-gp expression between the techniques (R2 = 0.29 and 0.05, respectively). In RT-PCR and Western blot, an internal reference protein is experimentally required; here, beta-actin was used which is innately variable along the intestinal tract. Quantification via LC-MS/MS can provide data on P-gp expression without the need for an internal reference protein and consequently, can give higher confidence on the expression levels of P-gp along the intestinal tract. Overall, these findings highlight similar trends between the species and suggest that the Wistar rat is an appropriate preclinical animal model to predict the oral drug absorption of P-gp substrates in the human small intestine.

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.

The simultaneous intake of food and drugs can have a strong impact on drug release, absorption, distribution, metabolism and/or elimination and consequently, on the efficacy and safety of pharmacotherapy. As such, food-drug interactions are one of the main challenges in oral drug administration. Whereas pharmacokinetic (PK) food-drug interactions can have a variety of causes, pharmacodynamic (PD) food-drug interactions occur due to specific pharmacological interactions between a drug and particular drinks or food. In recent years, extensive efforts were made to elucidate the mechanisms that drive pharmacokinetic food-drug interactions. Their occurrence depends mainly on the properties of the drug substance, the formulation and a multitude of physiological factors. Every intake of food or drink changes the physiological conditions in the human gastrointestinal tract. Therefore, a precise understanding of how different foods and drinks affect the processes of drug absorption, distribution, metabolism and/or elimination as well as formulation performance is important in order to be able to predict and avoid such interactions. Furthermore, it must be considered that beverages such as milk, grapefruit juice and alcohol can also lead to specific food-drug interactions. In this regard, the growing use of food supplements and functional food requires urgent attention in oral pharmacotherapy. Recently, a new consortium in Understanding Gastrointestinal Absorption-related Processes (UNGAP) was established through COST, a funding organisation of the European Union supporting translational research across Europe. In this review of the UNGAP Working group "Food-Drug Interface", the different mechanisms that can lead to pharmacokinetic food-drug interactions are discussed and summarised from different expert perspectives. ispartof: EUROPEAN JOURNAL OF PHARMACEUTICAL SCIENCES vol:134 pages:31-59 ispartof: location:Netherlands status: published

Liquid dosage forms have been widely applied in the pharmaceutical industry, with their applications ranging from oral preparations and injectables all the way through otic, nasal, rectal, and vaginal formulations. This chapter outlines the different types of liquid dosage forms, comparing their individual constituents and discussing their main features. A brief overview of the predominant methods of preparation has been included, along with the critical physical attributes to be considered when formulating them. In particular, focus has been given to their applications through different routes of administration with emphasis on the advantages that they offer over other pharmaceutical dosage forms.

For nearly four decades cancer-derived cell line monolayers have served as the recognized standard for the modeling of gastrointestinal (GI) absorption and have been widely used as a tool for oral drug development. However, they show limited in vivo predictability. We have developed approaches to cultivate porcine GI tissue and enable it to function ex vivo for prolonged periods. We then created an interface design that can achieve fully automated high-throughput interrogation of whole segments of the GI tract. This GI Tract-Tissue Robotic Interface System (GI-TRIS) demonstrated high predictive capacity of human oral drug absorption (Spearman correlation coefficient of 0.906 vs 0.302 for Caco-2 cell-based systems) while allowing a sample throughput of several thousand samples per day in a fully automated robotic facility. To examine the capacity of the GI-TRIS, we analyzed the intestinal absorption of 2930 formulations with the peptide drug oxytocin resulting in the discovery of an enhancer that resulted in an 11.3-fold increase in oral bioavailability of oxytocin in vivo in a large animal model while no disruption of the intestinal tissue was observed. In sum, the GI-TRIS system has the potential to transform oral drug formulation development and introduces the GI-TRIS concept as a pre-clinical strategy for a wide range of applications.

The rat is one of the most commonly used animal models in pre-clinical studies. Limited information between the sexes and the effect of food consumption on the gastrointestinal (GI) physiology, however, is acknowledged or understood. This study aimed to investigate the potential sex differences and effect of food intake on the intestinal luminal fluid and the efflux membrane transporter P-glycoprotein (P-gp) along the intestinal tract of male and female Wistar rats. To characterise the intestinal luminal fluids, pH, surface tension, buffer capacity and osmolality were measured. Absolute P-gp expression along the intestinal tract was quantified via liquid chromatography-tandem mass spectrometry (LC-MS/MS). In general, the characteristics of the luminal fluids were similar in male and female rats along the GI tract. In fasted male rats, the absolute P-gp expression gradually increased from the duodenum to ileum but decreased in the colon. A significant sex difference (p &lt, 0.05) was identified in the jejunum where P-gp expression in males was 83% higher than in females. Similarly, ileal P-gp expression in male rats was approximately 58% higher than that of their female counterparts. Conversely, following food intake, a significant sex difference (p &lt, 0.05) in P-gp expression was found but in a contrasting trend. Fed female rats expressed much higher P-gp levels than male rats with an increase of 77% and 34% in the jejunum and ileum, respectively. A deeper understanding of the effects of sex and food intake on the absorption of P-gp substrates can lead to an improved translation from pre-clinical animal studies into human pharmacokinetic studies.

Following oral administration, gastric emptying is often a rate-limiting step in the absorption of drugs and is dependent on both physiological and pharmaceutical factors. To guide translation into humans, small animal imaging during pre-clinical studies has been increasingly used to localise the gastrointestinal transit of solid dosage forms. In contrast to humans, however, anaesthesia is usually required for effective imaging in animals which may have unintended effects on intestinal physiology. This study evaluated the effect of anaesthesia and capsule size on the gastric emptying rate of coated capsules in rats. Computed tomography (CT) imaging was used to track and locate the capsules through the gastrointestinal tract. Two commercial gelatine mini-capsules (size 9 and 9h) were filled with barium sulphate (contrast agent) and coated using Eudragit L. Under the effect of anaesthesia, none of the capsules emptied from the stomach. In non-anaesthetised rats, most of the size 9 capsules did not empty from the stomach, whereas the majority of the smaller size 9h capsules successfully emptied from the stomach and moved into the intestine. This study demonstrates that even with capsules designed to empty from the stomach in rats, the gastric emptying of such solid oral dosage forms is not guaranteed. In addition, the use of anaesthesia was found to abolish gastric emptying of both capsule sizes. The work herein further highlights the utility of CT imaging for the effective visualisation and location of solid dosage forms in the intestinal tract of rats without the use of anaesthesia. This research was funded by the Engineering and Physical Sciences Research Council (EPSRC) UK, grant number EP/L01646X SI

The release and absorption profile of an oral medication is influenced by the physicochemical properties of the drug and its formulation, as well as by the anatomy and physiology of the gastrointestinal (GI) tract. During drug development the bioavailability of a new drug is typically assessed in early clinical studies in a healthy adult population. However, many disease conditions are associated with an alteration of the anatomy and/or physiology of the GI tract. The same holds true for some subpopulations, such as paediatric or elderly patients, or populations with different ethnicity. The variation in GI tract conditions compared to healthy adults can directly affect the kinetics of drug absorption, and thus, safety and efficacy of an oral medication. This review provides an overview of GI tract properties in special populations compared to healthy adults and discusses how drug absorption is affected by these conditions. Particular focus is directed towards non-disease dependent conditions (age, sex, ethnicity, genetic factors, obesity, pregnancy), GI diseases (ulcerative colitis and Crohn's disease, celiac disease, cancer in the GI tract, Roux-en-Y gastric bypass, lactose intolerance, Helicobacter pylori infection, and infectious diseases of the GI tract), as well as systemic diseases that change the GI tract conditions (cystic fibrosis, diabetes, Parkinson's disease, HIV enteropathy, and critical illness). The current knowledge about GI conditions in special populations and their impact on drug absorption is still limited. Further research is required to improve confidence in pharmacokinetic predictions and dosing recommendations in the targeted patient population, and thus to ensure safe and effective drug therapies. ispartof: EUROPEAN JOURNAL OF PHARMACEUTICAL SCIENCES vol:147 ispartof: location:Netherlands status: published

The aim of this study was to explore the influence of food on P-glycoprotein (P-gp) relative expression in both male and female rats, and its effect on intestinal permeation of P-gp substrates (ranitidine and ganciclovir) and a P-gp non-substrate (metformin). The intestine of 12 male and 12 female Wistar rats were excised and segmented into the duodenum, jejunum, ileum and colon. P-gp extracted from each segment was then determined via Western-blotting. In male rats, the relative P-gp expression decreased significantly after food intake in all segments of the intestine except in the duodenum. The most notable change was demonstrated in the colon where relative expression decreased from 1.75 ± 0.36 in the fasted-state to 0.31 ± 0.15 in the fed-state. In female rats, a fundamentally different result was observed. Food ingestion resulted in a significant increase in relative P-gp expression in all regions of the intestine except in the colon. The largest difference was observed in the jejunum of the fed-state female rat intestine where P-gp expression was 1.76 ± 0.95 which was a six-fold increase from the fasted state at 0.34 ± 0.13. Intestinal permeation studies in an Ussing chamber showed that both ganciclovir and ranitidine exhibited a sex difference in intestinal permeability in the fasted-state. No sex differences and food effects were observed on metformin small intestine permeability. The permeability results of the three drugs highly supported that there was a sex-related food effect on P-gp function in the small intestine. In summary, the current study reports stark differences between male and female rats at a physiological level relating to P-gp expression and the influence of food.

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

Selective laser sintering (SLS) is a three-dimensional printing (3DP) technology employed to manufacture plastic, metallic or ceramic objects. The aim of this study was to demonstrate the feasibility of using SLS to fabricate novel solid dosage forms with accelerated drug release properties, and with a view to create orally disintegrating formulations. Two polymers (hydroxypropyl methylcellulose (HPMC E5) and vinylpyrrolidone-vinyl acetate copolymer (Kollidon® VA 64)) were separately mixed with 5% paracetamol (used as a model drug) and 3% Candurin® Gold Sheen colorant; the powder mixes were subjected to SLS printing, resulting in the manufacture of printlets (3DP tablets). Modulating the SLS printing parameters altered the release characteristics of the printlets, with faster laser scanning speeds accelerating drug release from the HPMC formulations. The same trend was observed for the Kollidon® based printlets. At a laser scanning speed of 300 mm/s, the Kollidon® printlets exhibited orally disintegrating characteristics by completely dispersing in

Pre-clinical research often uses rodents as animal models to guide the selection of appropriate oral drug and dose selection in humans. However, traditionally, such research fails to consider the gastrointestinal differences between the sexes of rats and the impact on oral drug delivery. This study aimed to identify and characterise the potential sex-related differences in the gastrointestinal environment of sacrificed male and female Wistar rats. Their gastrointestinal tracts were excised and segmented into the stomach, duodenum, jejunum, ileum, caecum and colon. The respective contents and tissue sections were collected and analysed for pH, buffer capacity, surface tension, osmolality and relative P-glycoprotein (P-gp) expression. The pH in the stomach of females was found to be lower than in males. Female rats also exhibited a higher buffer capacity in the caecum and colon when compared with their male counterparts. Males were found to have a higher osmolality than females in the duodenum, ileum and colon. Significant sex differences (p

Professor Henry Higgins in My Fair Lady said, ‘Why can’t a woman be more like a man?’ Perhaps unintended, such narration extends to the reality of current drug development. A clear sex-gap exists in pharmaceutical research spanning from preclinical studies, clinical trials to post-marketing surveillance with a bias towards males. Consequently, women experience adverse drug reactions from approved drug products more often than men. Distinct differences in pharmaceutical response across drug classes and the lack of understanding of disease pathophysiology also exists between the sexes, often leading to suboptimal drug therapy in women. This review explores the influence of sex as a biological variable in drug delivery, pharmacokinetic response and overall efficacy in the context of pharmaceutical research and practice in the clinic. Prospective recommendations are provided to guide researchers towards the consideration of sex differences in methodologies and analyses. The promotion of disaggregating data according to sex to strengthen scientific rigour, encouraging innovation through the personalisation of medicines and adopting machine learning algorithms is vital for optimised drug development in the sexes and population health equity.

The absorption of oral drugs is frequently plagued by significant variability with potentially serious therapeutic consequences. The source of variability can be traced back to interindividual variability in physiology, differences in special populations (age- and disease-dependent), drug and formulation properties, or food-drug interactions. Clinical evidence for the impact of some of these factors on drug pharmacokinetic variability is mounting: e.g. gastric pH and emptying time, small intestinal fluid properties, differences in pediatrics and the elderly, and surgical changes in gastrointestinal anatomy. However, the link of colonic factors variability (transit time, fluid composition, microbiome), sex differences (male vs. female) and gut-related diseases (chronic constipation, anorexia and cachexia) to drug absorption variability has not been firmly established yet. At the same time, a way to decrease oral drug pharmacokinetic variability is provided by the pharmaceutical industry: clinical evidence suggests that formulation approaches employed during drug development can decrease the variability in oral exposure. This review outlines the main drivers of oral drug exposure variability and potential approaches to overcome them, while highlighting existing knowledge gaps and guiding future studies in this area. ispartof: EUROPEAN JOURNAL OF PHARMACEUTICAL SCIENCES vol:162 ispartof: location:Netherlands status: published

A robotic culture system for the high-throughput analysis of drug transport in porcine gastrointestinal tissue explants accurately predicts the absorption of orally taken drugs in the human gut.

Introduction: Three-dimensional (3D) printing is a relatively new, rapid manufacturing technology that has found promising applications in the drug delivery and medical sectors. Arguably, never before has the healthcare industry experienced such a transformative technology. This review aims to discuss the state of the art of 3D printing technology in healthcare and drug delivery. Areas covered: The current and future applications of printing technologies within drug delivery and medicine have been discussed. The latest innovations in 3D printing of customized medical devices, drug-eluting implants, and printlets (3D-printed tablets) with a tailored dose, shape, size, and release characteristics have been covered. The review also covers the state of the art of 3D printing in healthcare (covering topics such as dentistry, surgical and bioprinting of patient-specific organs), as well as the potential of recent innovations, such as 4D printing, to shape the future of drug delivery and to improve treatment pathways for patients. Expert opinion: A future perspective is provided on the potential for 3D printing in healthcare, covering strategies to overcome the major barriers to integration that are faced today.

Maple syrup urine disease (MSUD) is a rare metabolic disorder with a worldwide prevalence of 1 in every 185,000 live births. However, certain populations display a significant overexpression of the disorder where incidence is reported to be 1 in every 52,541 new-borns. The first-line therapy for MSUD involves a strict dietary leucine restriction and oral supplementation of isoleucine and valine. The dose administered to patients requires strict tailoring according to age, weight and blood levels. In current clinical practice, however, practitioners still have to prepare extemporaneous formulations due to the lack of suitable oral treatments for MSUD. Herein, we evaluate the first time use of 3D printing in a hospital setting for the preparation of personalised therapies with the aim of improving safety and acceptability to isoleucine supplementation in paediatric patients suffering from MSUD. This investigation was a single-centre, prospective crossover experimental study. Four paediatric patients with MSUD (aged 3–16 years) were treated at the Clinic University Hospital in Santiago de Compostela, Spain which is a MSUD reference hospital in Europe. The primary objective was to evaluate isoleucine blood levels after six months of treatment with two types of formulations; conventional capsules prepared by manual compounding and personalised chewable formulations prepared by automated 3D printing. A secondary investigation was to evaluate patient acceptability of 3D printed formulations prepared with different flavours and colours. Isoleucine blood levels in patients were well controlled using both types of formulations, however, the 3D printed therapy showed mean levels closer to the target value and with less variability (200–400 µM). The 3D printed formulations were well accepted by patients regarding flavour and colour. The study demonstrates for the first time that 3D printing offers a feasible, rapid and automated approach to prepare oral tailored-dose therapies in a hospital setting. 3D printing has shown to be an effective manufacturing technology in producing chewable isoleucine printlets as a treatment of MSUD with good acceptability.

It is known that males and females respond differently to medicines and that differences in drug behaviour are due to inter-individual variability and sex specificity. In this work, we have examined the influence of pharmaceutical excipients on drug bioavailability in males and females. Using a rat model, we report that a portfolio of polyoxyethylated solubilising excipients (polyethylene glycol 2000, Cremophor RH 40, Poloxamer 188 and Tween 80) increase ranitidine bioavailability in males but not in females. The in vivo sex and excipient effects were reflected in vitro in intestinal permeability experiments using an Ussing chamber system. The mechanism of such an effect on drug bioavailability is suggested to be due to the interaction between the excipients and the efflux membrane transporter P-glycoprotein (P-gp), whose expression in terms of gene and protein levels were inhibited by the solubilising agents in male but not in female rats. In contrast, the non-polyoxyethylated excipient, Span 20, significantly increased ranitidine bioavailability in both males and females in a non-sex-dependent manner. These findings have significant implications for the use of polyoxyethylated solubilising excipients in drug formulation in light of their sex-specific modulation on the bioavailability of drugs that are P-gp substrates. As such, pharmaceutical research is required to retract from a &lsquo, one size fits all&rsquo, approach and to, instead, evaluate the potential impact of the interplay between excipients and sex on drug effect to ensure effective pharmacotherapy.

Active pharmaceutical ingredients are routinely formulated with a range of excipients in the manufacture of drug products. Excipients are considered to be inert components of the formulations, although recent research has contested its inactive behaviour. This study investigated the effect of the excipient polyethylene glycol 400 (PEG 400) on the oral bioavailability and intestinal permeability of cimetidine in male and female human volunteers. Aqueous solutions of cimetidine with pharmaceutically relevant concentrations of PEG 400 at 0% w/v (control), 0.3% w/v, 0.5% w/v, 0.7% w/v and 1.0% w/v were orally administered to both sexes. Urine samples were then collected and assayed for the determination of cimetidine which reflected oral bioavailability. This human study showed that PEG 400 at 0.3% w/v, 0.5% w/v and 0.7% w/v concentrations significantly increased cimetidine bioavailability by 34%, 58% and 41% respectively, although this enhancement was only demonstrated in men and not women (p 0.05). Ussing chamber transport studies with male human jejunal tissues revealed that cimetidine permeability increased by 26%, 48% and 29% with PEG 400 at 0.3% w/v, 0.5% w/v and 0.7% w/v respectively (p 0.05). No such enhancement was demonstrated in female tissues (p 0.05). We have shown that PEG 400 interacts with intestinal P-glycoprotein (P-gp) expression differently in males and females. The mechanistic action of PEG 400 at gut level was further investigated on human jejunal tissues following the pre-treatment of the P-gp inhibitor PSC 833 (valspodar) on the transport of cimetidine. When intestinal P-gp was inhibited, the sex- and dose-dependent modulatory effect of PEG 400 with cimetidine was completely eradicated, thus confirming that PEG 400 has a modulatory - rather than inhibitory - effect on P-gp. In sum, the widely used excipient PEG 400 is not inert at pharmaceutically relevant concentrations and its modulatory effect is demonstrated at a human clinical level. Such pharmacological effects, however, are sex- and dose-dependent via its modulation on intestinal P-gp, as evidenced by the boost in cimetidine bioavailability only in male human volunteers. As such, these findings should be carefully considered towards the co-formulation of PEG 400 with drugs that are P-gp substrates.

The introduction of three-dimensional (3D) printing in the pharmaceutical arena has caused a major shift towards the advancement of modern medicines, including drug products with different configurations and complex geometries. Otherwise challenging to create via conventional pharmaceutical techniques, 3D printing technologies have been explored for the fabrication of multi-drug loaded dosage forms to reduce pill burden and improve patient adherence. In this study, stereolithography (SLA), a vat polymerisation technique, was used to manufacture a multi-layer 3D printed oral dosage form (polyprintlet) incorporating four antihypertensive drugs including irbesartan, atenolol, hydrochlorothiazide and amlodipine. Although successful in its fabrication, for the first time, we report an unexpected chemical reaction between a photopolymer and drug. Fourier Transform Infrared (FTIR) spectroscopy and Nuclear Magnetic Resonance (NMR) spectroscopy confirmed the occurrence of a Michael addition reaction between the diacrylate group of the photoreactive monomer and the primary amine group of amlodipine. The study herein demonstrates the importance of careful selection of photocurable resins for the manufacture of drug-loaded oral dosage forms via SLA 3D printing technology.

It was in 400 BC that Hippocrates reportedly stated that "death sits in the colon". The growth in our knowledge of the intestinal microbiome, the gut-brain axis and their function and imbalance has distinctly uncovered the complex relationship between the gut to disease predisposition and development, heralding the problem and the solution to disease pathology. Human studies of new drug molecules are typically performed in healthy volunteers and their specific disease indication. Approved drugs, however, are used by patients with diverse disease backgrounds. Here, we review the current literature of the gastrointestinal tract reacting to systemic disease pathology that elicits physiological and functional changes that consequently affect oral drug product performance.

Three-dimensional printing (3DP) is gaining momentum in the field of pharmaceuticals, offering innovative opportunities for medicine manufacture. Selective laser sintering (SLS) is a novel, high resolution and single-step printing technology that we have recently introduced to the pharmaceutical sciences. The aim of this work was to use SLS 3DP to fabricate printlets (3D printed tablets) with cylindrical, gyroid lattice and bi-layer structures having customisable release characteristics. Paracetamol-loaded constructs from four different pharmaceutical grade polymers including polyethylene oxide, Eudragit (L100-55 and RL) and ethyl cellulose, were created using SLS 3DP. The novel gyroid lattice structure was able to modulate the drug release from all four polymers. This work is the first to demonstrate the feasibility of using SLS to achieve customised drug release properties of several polymers, in a swift, cost-effective manner, avoiding the need to alter the formulation composition. By creating these constructs, it is therefore possible to modify drug release, which in practice, could enable the tailoring of drug performance to the patient simply by changing the 3D design.

Three-dimensional printing (3DP) is an entirely novel method of manufacture with its applications only limited by the imagination. The mainstay of 3DP utilisation practically to date has been in the field of engineering, largely for the purpose of generating model prototypes. However, the potential of 3DP has increasingly been recognised in areas of commercial manufacture in medicine due to its capacity to produce materials and devices that can equal, if not surpass, the benefits of traditional consumer goods. The opportunities for future uses are innumerable ranging from tissue engineering, the on-demand fabrication of medical devices and advanced applications in other fields with the same pressing need for medical personalisation. The 3D printing arena is ultimately exciting and endless in opportunities with the FDA encouraging the development of science and risk based approaches. This chapter will discuss the existing and future medical applications of 3DP and its potential to revolutionise medical practice.

We now stand on the brink of a fourth industrial revolution. By the remarkable technological advancements of the twenty-first century, manufacturing is now becoming digitalised. In the last decade, the rise of rapid prototyping has provided individual patient care, acted as an educational and training tool and contributed to research. Innovative technologies such as three-dimensional printing (3DP), have the potential to cause a paradigm shift in medicine design, manufacture and use. Instead of using conventional large batch processes, customised printlets (3D printed tablets) with a tailored dose, shape, size and release characteristics could be produced on-demand. Arguably, never before has the pharmaceutical industry experienced such a transformative technology in medicines manufacture. Indeed, this technology could be utilised throughout the drug development process, ranging from pre-clinical development and first-in-human clinical trials through to front-line medical care (personalized medicines). This chapter aims to discuss the current and future potential applications of 3DP in healthcare and, ultimately, the power of 3DP in pharmaceuticals.

Binder jet printing is arguably the most successful three-dimensional printing (3DP) technology in the pharmaceutical industry to date. In 2015, the binder jet process was adapted as an alternative mass manufacturing technique to enable the production of Spritam® (the first 3D printed tablet) approved by the Food and Drug Administration (FDA). Binder jet printing is expected to continue making a widespread impact to formulation manufacture over the next decade. In particular, binder jet printing offers benefits of producing oral dosage forms with unique release characteristics ranging from fast-dissolving through to controlled-release platforms. This chapter aims to discuss the history and methodology of binder jet printing, pharmaceutical and medical applications, considerations for formulations development and advantages and disadvantages of such processes in the pharmaceutical space.

The rise in three-dimensional (3D) printing in design and manufacturing, like any other, is the product of vision and implementation, pioneered by those who were brave enough to make it happen. In this chapter, the advancements of exponential developments driven by 3D printers themselves and its application in almost all areas of manufacturing and personalisation, namely; aeronautics, engineering, architecture and pharmaceutics are discussed. This chapter further serves to provide an introduction to the different 3D printing technologies, their respective histories, potential benefits, limitations and regulatory requirements, and a thorough description of the new and exciting possibilities that can arise by simply acknowledging the capabilities of 3D printing in healthcare.