Possibility of a patch system as a new oral delivery system

Smart pills and drug delivery devices enabling next generation oral dosage forms

Oral dosage forms are the preferred solution for systemic treatment and prevention of disease conditions. However, traditional dosage forms face challenges regarding treatment adherence and delivery of biologics. Oral therapies that require frequent administrations face difficulties with patient compliance. In addition, only a few peptide- and protein-based drugs have been commercialized for oral administration so far, presenting a bioavailability that is generally low. Therefore, research and development on novel formulation strategies for oral drug delivery has bloomed massively in the last decade to overcome these challenges. On the one hand, approaches based on lumen-release of drugs such as 3D-printed capsules and prolonged gastric residence dosage forms have been explored to offer personalized medicine to the patient and reduce frequent dosing of small drug compounds that are currently in the market as powdered tablet or capsules. On the other hand, strategies based on mucus interfacing such as gastrointestinal patches, or even epithelium injections have been investigated in order to enhance the permeability of biologic macromolecules, which are mostly commercialized in the form of subcutaneous injections. Despite the fact that these methods are at an early development stage, promising results have been revealed in terms of personalized medicine and improved bioavailability. In this review, we offer a critical overview of novel ingestible millimeter-sized devices and technologies for oral drug delivery that are currently used in the clinic as well as those that could emerge on the market in a not too distant future.

Formulation strategies to improve the efficacy of intestinal permeation enhancers. Adv Drug Deliv Rev 2021;177:113925. [PMID: 34418495 DOI: 10.1016/j.addr.2021.113925]

The use of chemical permeation enhancers (PEs) is the most widely tested approach to improve oral absorption of low permeability active agents, as represented by peptides. Several hundred PEs increase intestinal permeability in preclinical bioassays, yet few have progressed to clinical testing and, of those, only incremental increases in oral bioavailability (BA) have been observed. Still, average BA values of ~1% were sufficient for two recent FDA approvals of semaglutide and octreotide oral formulations. PEs are typically screened in static in vitro and ex-vivo models where co-presentation of active agent and PE in high concentrations allows the PE to alter barrier integrity with sufficient contact time to promote flux across the intestinal epithelium. The capacity to maintain high concentrations of co-presented agents at the epithelium is not reached by standard oral dosage forms in the upper GI tract in vivo due to dilution, interference from luminal components, fast intestinal transit, and possible absorption of the PE per se. The PE-based formulations that have been assessed in clinical trials in either immediate-release or enteric-coated solid dosage forms produce low and variable oral BA due to these uncontrollable physiological factors. For PEs to appreciably increase intestinal permeability from oral dosage forms in vivo, strategies must facilitate co-presentation of PE and active agent at the epithelium for a sustained period at the required concentrations. Focusing on peptides as examples of a macromolecule class, we review physiological impediments to optimal luminal presentation, discuss the efficacy of current PE-based oral dosage forms, and suggest strategies that might be used to improve them.

Intestinal patches with an immobilized solid-in-oil formulation for oral protein delivery

Oral administration of biomolecular drugs such as peptides, proteins, and DNA is an attractive delivery method because of the safety and convenience of delivery in contrast to injection administration. However, oral delivery of biomolecules has several potential barriers such as enzymatic degradation in the gastrointestinal tract and low permeability across an intestinal membrane. In this study, we proposed an intestinal patch system that included surfactant-coated insulin for oral delivery. The intestinal patches, which have mucoadhesive and drug-impermeable layers, induced sustained unidirectional insulin release toward intestinal mucosa and inhibition of insulin leakage from the patches. Moreover, the surfactant-coated insulin, which has high compatibility with cell membranes, enhanced insulin transport across the intestinal membrane. This study demonstrates that the intestinal patches might improve protein permeability in the intestinal mucosa, thereby offering an innovative therapeutic strategy.

Advances in gastro retentive drug-delivery systems

INTRODUCTION

In recent years, various technological improvements have been achieved and new concepts have been developed, in the area of controlled release solid oral dosage forms, especially for products where an extended time of release is associated with an extended gastric retention time. These Gastro Retentive Systems have been quite investigated because they can improve the in-vivo performance of many drugs.

AREAS COVERED

This paper summarizes current approaches in the research and development of gastro retentive dosage forms from recent literature. Apart from the numerous mechanisms of action involved, a short review of different key parameters is proposed, taking into account the stomach physiology. Most of the current technologies published, patented or marketed are presented. Promising drugs to develop in the near future are mentioned, and the importance of such systems in fixed Dose Combinations is also discussed. The importance of food effect is mentioned, and the impact of the multiple unit systems versus monolithic approach is discussed, especially regarding the dose intake.

EXPERT OPINION

In conclusion, numerous mechanisms like floating, sinking, effervescence, swelling, bioadhesion, magnetic, etc. have been proposed over the years. While most of the proposed systems show promising dissolution profiles and in-vitro retention, only few of them have also shown success in-vivo. Currently, the polymeric swelling monolithic systems are the most prominent marketed forms. The possibility to combine different mechanisms in order to ensure true gastric retention even in the fasted state should be further investigated.

Concentration and surface of absorption: concepts and applications to gastrointestinal patches delivery

Gastrointestinal patches represent a novel multiparticulate drug delivery system able to increase the intestinal absorption of drugs with poor bioavailability. The number of patches to administer is a critical issue since it is related to the surface and drug concentration at the absorption site. The objective of this article is to evaluate the effect of the number of administered patches on the final absorption of leuprolide, a peptide chosen as model drug, assuming complete adhesion of all the devices to the intestinal membrane. The same dose of leuprolide was encapsulated into 2, 4 and 6 patches; the resulting intestinal absorption profiles were measured with the Ussing chamber ex vivo experimental setup and compared between them. The results showed that varying the number of patches, the final absorption does not present statistically significant changes, indicating that changes in concentration are balanced by change in absorption surface. These experimental findings can also be explained considering the equation that links the drug flow to surface and concentration at the absorption site, showing that the drug flow is related only to the geometry of each individual patch.

Nanoengineered surfaces enhance drug loading and adhesion

To circumvent the barriers encountered by macromolecules at the gastrointestinal mucosa, sufficient therapeutic macromolecules must be delivered in close proximity to cells.(1) Previously, we have shown that silicon nanowires penetrate the mucous layer and adhere directly to cells under high shear.(2) In this work, we characterize potential reservoirs and load macromolecules into interstitial space between nanowires. We show significant increases in loading capacity due to nanowires while retaining adhesion of loaded particles under high shear.

Engineering strategies to enhance nanoparticle-mediated oral delivery

Oral delivery is the most preferred route of drug administration due to convenience, patient compliance and cost-effectiveness. Despite these advantages it remains difficult to achieve satisfactory bioavailability levels via oral administration due to the harsh environment of the gastrointestinal (GI) tract, particularly for biomacromolecules. One promising method to increase the bioavailability of macromolecular drugs such as proteins and nucleic acids is to encapsulate them in nanoparticles before oral administration. This review describes innovative strategies for increasing the efficacy of nanoparticle-mediated delivery to the GI tract. Approaches to optimize nanoparticle formulation by exploiting mucoadhesion, environmental responsiveness and external delivery control mechanisms are discussed. The application of recent advances in nanoparticle synthesis using supercritical fluids, microfluidics and imprint lithography to oral delivery are also presented, as well as possible strategies for incorporating nanoparticles into micro- and macroscale oral delivery devices.

Absorption of interferon alpha from patches in rats

Interferon alpha (IFN-alpha), patch preparations composed of three layers, water-insoluble backing layer, drug containing layer with absorption enhancer and surface layer containing pH-dependent polymer were prepared. As absorption enhancer, three surfactants, Gelucire44/14 (Lauroyl macrogol-32 glycerides), Labrasol (Caprylocaproyl macrogol-8 glycerides) and HCO-60 (polyoxyethylated hydrogenerated castor oil) were used in preparing IFN-alpha patch preparations. The intestinal absorption of IFN-alpha was studied after the administration of test patch preparations into the rat jejunum, 50,000 IU/kg. The serum IFN-alpha levels were measured by an ELISA method and both C(max) and AUC were determined as the index of absorption of IFN-alpha. Gelucire44/14 preparation including Pharmasol for the stable solidification showed the higher C(max), 7.66 +/- 0.82 IU/ml, and AUC, 12.85 +/- 1.49 IU h/ml, than Labrasol (6.51 +/- 0.89 and 8.30 +/- 1.34 IU h/ml) and HCO-60 (6.02 +/- 1.14, 7.53 +/- 1.84 IU h/ml) preparations, respectively. By comparing to the AUC obtained after s.c. injection of the same dose of IFN-alpha to rats, bioavailability (BA) was estimated to be 7.8% in Gelucire44/14 preparation. In vitro release study showed that the T50%s, the time when half of the formulated IFN-alpha is released from the patches, were 3.4 +/- 0.1 min for HCO-60, 7.8 +/- 0.1 min for Gelucire44/14 and 11.4 +/- 0.1 min for Labrasol preparations. To study the effect of absorption site, Gelucire44/14 preparation was administered into the rat duodenum and ileum. However, there were not significant differences on AUC among the three absorption sites. By reducing the IFN-alpha dose from 50,000 to 25,000 IU/kg, the serum IFN-alpha levels vs time profile showed a tendency of dose-dependency. When the histological examination of small intestinal mucosa was carried out in this study, the small intestinal mucosa after the Gelucire44/14 patches administered and before it was administered, could not recognize impaired. From these results, the usefulness of oral patch system for the oral delivery of IFN-alpha has been proved in rats.

Gastro-intestinal patch system for the delivery of erythropoietin

The absorption of erythropoietin (EPO) from rat small intestine was studied using gastro-intestinal patches (GI-PS) in the presence of absorption enhancers. Surfactants such as a saturated polyglycolysed C8-C18 glyceride (Gelucire 44/14), PEG-8 capryl/caprylic acid glycerides (Labrasol), and polyoxyethylene hydrogenated castor oil derivative (HCO-60) were used as absorption enhancers at 143, 94 and 20 mg/kg, respectively. The absorption of EPO was studied by measuring serum EPO levels by an ELISA method after small intestinal administration of EPO-GI-PS preparation in rats at the EPO dose level of 100 IU/kg. Labrasol showed the highest absorption enhancing effect after intrajejunum administration with maximum serum EPO level of 84.1+/-11.4 mIU/ml while Gelucire 44/14 and HCO-60 showed 43.5+/-9.8 and 26.5+/-2.3 mIU/ml, respectively. The appropriate site for EPO absorption was also investigated. Jejunum was found to be the most efficient absorption site for the absorption of EPO from GI-PS. Using Labrasol as the absorption enhancer and jejunum as the absorption site, the effect of EPO dose on EPO absorption was studied by increasing the EPO dose from 50, to 100, 300 and 600 IU/kg. It was found that 100 IU/kg was the optimum dose with a serum EPO level of 84.1+/-11.4 mIU/ml while escalating doses showed decreases in serum EPO levels 48.3+/-5.6 for 300 IU/kg and 50.6+/-10.3 mIU/ml for 600 IU/kg. The percent bioavailability (BA) of EPO-GI-PS with Labrasol as absorption enhancer was 7.9 at 50 IU/kg, 12.1 at 100 IU/kg, 3.2 at 300 IU/kg and 1.2 at 600 IU/kg. Histological studies showed no adverse effect at the site of administration.

Micromachined devices: the impact of controlled geometry from cell-targeting to bioavailability

Advances in microelectomechanical systems (MEMS) have allowed the microfabrication of polymeric substrates and the development of a novel class of controlled delivery devices. These vehicles have specifically tailored three-dimensional physical and chemical features which, together, provide the capacity to target cells, promote unidirectional controlled release, and enhance permeation across the intestinal epithelial barrier. Examining the biological response at the microdevice biointerface may provide insight into the benefits of customized surface chemistry and structure in terms of complex drug delivery vehicle design. Therefore, the aim of this work was to determine the interfacial effects of selective surface chemistry and architecture of tomato lectin (TL)-modified poly(methyl methacrylate) (PMMA) drug delivery microdevices on the Caco-2 cell line, a model of the gastrointestinal tract.

Gastrointestinal patch systems for oral drug delivery

Gastrointestinal patch systems with integrated multifunctions could surmount the challenges associated with conventional drug delivery. Several gastrointestinal patch systems provide bioadhesion, drug protection and unidirectional release. This combination of function could improve the overall oral bioavailability of large molecules that can currently be delivered only by injection, for example, epoetin-alpha and granulocyte-colony-stimulating factor, which are commonly used to treat chemotherapy-associated anemia and leukopenia, respectively. Furthermore, self-regulated release and cell-specific targeting provide additional 'smart' characteristics to this innovative therapeutic platform.