An overview of intestinal wafers for oral drug delivery

Intestinal retentive systems - recent advances and emerging approaches

Intestinal retentive devices (IRDs) are devices designed to anchor within the lumen of the intestines for long-term residence in the gastrointestinal tract. IRDs can enable impactful medical device technologies including sustained oral drug delivery systems, indwelling sensors, or real-time diagnostics. The design and testing of IRDs present a myriad of challenges, including precise deployment of the device at desired intestinal locations, secure anchoring within the gastrointestinal tract to allow for natural function, and safe removal of the IRD at user-defined times. Advancing the state-of-the-art of IRD is an interdisciplinary effort that requires innovations such as new materials, novel anchoring mechanisms, and medical device design with consistent input from clinical practitioners and end-users. This perspective briefly reviews the current state-of-the-art for IRDs and charts a path forward to inform the design of future concepts. Specifically, this article will highlight materials, retention mechanisms, and test beds to measure the efficacy of IRDs and their mechanisms. Finally, potential synergies between IRD and other medical device technologies are presented to identify future opportunities.

Challenges and Opportunities in the Oral Delivery of Recombinant Biologics

Recombinant biological molecules are at the cutting-edge of biomedical research thanks to the significant progress made in biotechnology and a better understanding of subcellular processes implicated in several diseases. Given their ability to induce a potent response, these molecules are becoming the drugs of choice for multiple pathologies. However, unlike conventional drugs which are mostly ingested, the majority of biologics are currently administered parenterally. Therefore, to improve their limited bioavailability when delivered orally, the scientific community has devoted tremendous efforts to develop accurate cell- and tissue-based models that allow for the determination of their capacity to cross the intestinal mucosa. Furthermore, several promising approaches have been imagined to enhance the intestinal permeability and stability of recombinant biological molecules. This review summarizes the main physiological barriers to the oral delivery of biologics. Several preclinical in vitro and ex vivo models currently used to assess permeability are also presented. Finally, the multiple strategies explored to address the challenges of administering biotherapeutics orally are described.

Hydrocaffeic acid-chitosan coating of gastric patch provides long-acting mucoadhesive delivery of model chemotherapeutic agent

The development of a long-acting orally administered dosage form is a challenge. Here, we report development of a multi-layered mucoadhesive gastric patch that could deliver entrapped chemotherapeutic agent for eight days after oral administration. The multi-layered patch was designed to contain core layer, mucoadhesive layer and backing layer. The core layer contained the model chemotherapeutic agent, regorafenib. The mucoadhesive layer made of chitosan-hydrocaffeic acid conjugate showed greatest mucoadhesion strength of 18.1 ± 0.78 kPa in freshly excised rat gastric mucosa. The backing layer made of hydrophobic polycaprolactone-polydimethylsiloxane composite showed the contact angle of 120 ± 4.7° after placement of water drop. The entrapped regorafenib predominantly released from the mucoadhesive-side of the patch into simulated gastric fluid and showed a zero-order release profile. The patches were found to be stable for desired characteristics for up to 3 months in long term storage conditions. The pharmacokinetic studies in rat model revealed constant plasma concentration of regorafenib sustained for 8 days after oral administration of gastric patch. The gastric tissue where the patch adhered for 8 days did not show any significant histological changes compared with the normal gastric tissue. The oral administration of single dose of regorafenib-loaded gastric patch in FaDu cell xenografted tumor bearing athymic nude mice has shown significant (P < 0.05) reduction in the tumor volume over 7 days compared to the control group. Taken together, the multi-layered mucoadhesive gastric patch can be developed as a long-acting oral drug delivery system.

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.

Functionalized polymeric patch for localized oxaliplatin delivery to treat gastric cancer

Localized delivery of chemotherapeutic agents allows extended drug exposure at the target site, thereby reducing systemic toxicity. We report the development of functionalized polymeric patch with unidirectional drug release to treat gastric cancer. The oxaliplatin-loaded patch was prepared by incorporating sodium carboxymethyl cellulose, hydroxypropyl cellulose and polyvinylpyrrolidone. The patch was functionalized by coating with transferrin-poly(lactic-co-glycolic acid) conjugate on one side of the patch for cancer targeting. The other side of the patch was coated with ethylcellulose (EC) to restrict the release of oxaliplatin. The physical and mechanical properties of oxaliplatin-loaded patches were characterized. Mucoadhesion studies using excised rat stomach tissue have shown that the functionalized side of the patch has significantly (p < 0.05) greater mucoadhesion strength compared with EC coated side of the patch. The in vitro and ex vivo (stomach sac and open-membrane model) studies revealed greater permeation of oxaliplatin across the stomach tissue when adhered to the functionalized and non-functionalized side of the patch compared with EC coated side. It was found that the growth inhibition with oxaliplatin solution was not significantly greater compared with corresponding concentrations of oxaliplatin-loaded patch in AGS and Caco-2 cell models. The in vivo studies were performed in mice, where indocyanine green-loaded patch encapsulated in a gelatin capsule was orally administered. The near-infrared (NIR) optical imaging revealed adherence of the patch on the mucosal side of the stomach tissue for up to 6 h. In conclusion, the functionalized polymeric patch loaded with oxaliplatin can be a potential localized delivery system to target gastric cancer.

Sensing technologies and experimental platforms for the characterization of advanced oral drug delivery systems

Complex and miniaturized oral drug delivery systems are being developed rapidly for targeted, controlled drug release and improved bioavailability. Standard analytical techniques are widely used to characterize i) drug carrier and active pharmaceutical ingredients before loading into a delivery device (to ensure the solid form), and ii) the entire drug delivery system during the development process. However, in light of the complexity and the size of some of these systems, standard techniques as well as novel sensing technologies and experimental platforms need to be used in tandem. These technologies and platforms are discussed in this review, with a special focus on passive delivery systems in size range from a few 100 µm to a few mm. Challenges associated with characterizing these systems and evaluating their effect on oral drug delivery in the preclinical phase are also discussed.

Establishment of a Dissolution Test System for the Biorelevant Characterization of Esophageal Applied Dosage Forms

There is a high demand for drug delivery systems that enable local therapy of esophageal diseases such as eosinophilic esophagitis. For the development of such drug delivery systems, suitable in vitro test procedures are needed that allow a biorelevant characterization of dosage forms. With the help of the new test system presented in this thesis it is now possible to simulate the application site esophagus and to characterize the dissolution behavior of esophageal applied drug delivery systems under special consideration of physiological parameters like salivary flow rate, intensity of peristalsis, and posture of the patient. In this work, the dissolution of mucoadhesive films for esophageal application with the new device was investigated and compared to the results obtained with the compendial standard device (USP 2 apparatus). The results show that the novel test system is a promising tool for the early evaluation of locally applied oral formulations for esophageal application.

Micro and nanoscale technologies in oral drug delivery

Oral administration is a pillar of the pharmaceutical industry and yet it remains challenging to administer hydrophilic therapeutics by the oral route. Smart and controlled oral drug delivery could bypass the physiological barriers that limit the oral delivery of these therapeutics. Micro- and nanoscale technologies, with an unprecedented ability to create, control, and measure micro- or nanoenvironments, have found tremendous applications in biology and medicine. In particular, significant advances have been made in using these technologies for oral drug delivery. In this review, we briefly describe biological barriers to oral drug delivery and micro and nanoscale fabrication technologies. Micro and nanoscale drug carriers fabricated using these technologies, including bioadhesives, microparticles, micropatches, and nanoparticles, are described. Other applications of micro and nanoscale technologies are discussed, including fabrication of devices and tissue engineering models to precisely control or assess oral drug delivery in vivo and in vitro, respectively. Strategies to advance translation of micro and nanotechnologies into clinical trials for oral drug delivery are mentioned. Finally, challenges and future prospects on further integration of micro and nanoscale technologies with oral drug delivery systems are highlighted.

Oral Drug Delivery Technologies-A Decade of Developments

Advanced drug delivery technologies, in general, enable drug reformulation and administration routes, together contributing to life-cycle management and allowing the innovator to maintain the product monopoly. Over the years, there has been a steady shift from mere life-cycle management to drug repurposing-applying delivery technologies to tackle solubility and permeability issues in early stages or safety and efficacy issues in the late stages of drug discovery processes. While the drug and the disease in question primarily drive the choice of route of administration, the oral route, for its compliance and safety attributes, is the most preferred route, particularly when it comes to chronic conditions, including pain, which is not considered a disease but a symptom of a primary cause. Therefore, the attempt of this review is to take a stock of the advances in oral delivery technologies that are applicable for injectable to oral transformation, improve risk-benefit profiles of existing orals, and apply them in the early discovery program to minimize the drug attrition rates.

Localized drug delivery with mono and bilayered mucoadhesive films and wafers for oral mucosal infections

Local drug delivery into oral cavity offers many advantages over systemic administration in treatment of the oral infections. In this study, monolayer and bilayered mucoadhesive film and wafer formulations were developed as local drug delivery platforms using chitosan and hydroxypropyl methylcellulose (HPMC). Cefuroxime axetil (CA) was used as the model drug. Surface morphology, mechanical strength, water uptake, in vitro adhesion, disintegration and in vitro release properties of the formulations were investigated. Furthermore, antimicrobial activity of the formulations was evaluated against E. coli and S. aureus. HPMC based formulations were found to disintegrate within <30 min whereas chitosan based formulations remained intact up to 6 h. Significantly higher drug release was obtained with wafer formulations. Antimicrobial activity was found to increase in presence of chitosan, and HPMC was also observed to contribute to this action. Bilayered wafer formulation, with adhesive chitosan backing layer and HPMC based drug loaded layer, providing prolonged drug release and suitable adhesive properties, with suitable mechanical strength, would be suggested as a promising local delivery system for treatment of the infections in the oral cavity.