Critical view on drug dissolution in artificial saliva: A possible use of in-line e-tongue measurements

Controlling Oral Polymicrobial Biofilm Using Usnic Acid on the Surface of Titanium in the Artificial Saliva Media

Background/Objectives: Titanium dental implants, while highly successful, face challenges due to polymicrobial infections leading to peri-implantitis and implant failure. Biofilm formation on implant surfaces is the primary cause of these infections, with factors such as matrix production and cross-kingdom interactions contributing to the microbial accumulation of bacterial and fungal pathogens species. To combat this issue, naturally derived molecules have been reported to overcome the hurdle of antimicrobial resistance against the application of conventional antibiotics and antifungals. Methods: The present study aimed to employ the lichen-derived molecules, usnic acid (UA), to retard the development of biofilms of bacterial and fungal pathogens on the surface of titanium kept in the human artificial saliva (HAS) working as a growth-supporting, host-mimicking media. Results: The minimum inhibitory concentration of UA in HAS towards Candida albicans was >512 µg/mL, whereas against Staphylococcus aureus and Streptococcus mutans, it was determined to be 512 µg/mL. Whereas, in the standard growth media, the MIC value of UA towards S. mutans and S. aureus were 8 and 16 µg/mL; however, against C. albicans, it was 512 µg/mL. UA synergistically enhanced the efficacy of the antibiotics toward bacterial pathogens and the efficacy of antifungals against C. albicans. The antibiofilm results depict the fact that in the HAS, UA significantly reduced both mono-species of S. mutans, S. aureus, and C. albicans and mixed-species biofilm of C. albicans with S. mutans and S. aureus on the surface of the titanium. Conclusions: The present study showed that UA is a promising natural drug that can control oral polymicrobial disease as a result of the application of dental implants.

Critical View on the Qualification of Electronic Tongues Regarding Their Performance in the Development of Peroral Drug Formulations with Bitter Ingredients

In this review, we aim to highlight the advantages, challenges, and limitations of electronic tongues (e-tongues) in pharmaceutical drug development. The authors, therefore, critically evaluated the performance of e-tongues regarding their qualification to assess peroral formulations containing bitter active pharmaceutical ingredients. A literature search using the keywords 'electronic', 'tongue', 'bitter', and 'drug' in a Web of Science search was therefore initially conducted. Reviewing the publications of the past decade, and further literature where necessary, allowed the authors to discuss whether and how e-tongues perform as expected and whether they have the potential to become a standard tool in drug development. Specifically highlighted are the expectations an e-tongue should meet. Further, a brief insight into the technologies of the utilized e-tongues is given. Reliable protocols were found that enable (i) the qualified performance of e-tongue instruments from an analytical perspective, (ii) proper taste-masking assessments, and (iii) under certain circumstances, the evaluation of bitterness.

Electronic Tongue for Direct Assessment of SARS-CoV-2-Free and Infected Human Saliva-A Feasibility Study

An electronic tongue is a powerful analytical instrument based on an array of non-selective chemical sensors with a partial specificity for data gathering and advanced pattern recognition methods for data analysis. Connecting electronic tongues with electrochemical techniques for data collection has led to various applications, mostly within sensing for food quality and environmental monitoring, but also in biomedical research for the analyses of different bioanalytes in human physiological fluids. In this paper, an electronic tongue consisting of six electrodes (viz., gold, platinum, palladium, titanium, iridium, and glassy carbon) was designed and tested in authentic (undiluted, unpretreated) human saliva samples from eight volunteers, collected before and during the COVID-19 pandemic. Investigations of 11 samples using differential pulse voltammetry and a principal component analysis allowed us to distinguish between SARS-CoV-2-free and infected authentic human saliva. This work, as a proof-of-principle demonstration, provides a new perspective for the use of electronic tongues in the field of enzyme-free electrochemical biosensing, highlighting their potential for future applications in non-invasive biomedical analyses.

Buccal films: A review of therapeutic opportunities, formulations & relevant evaluation approaches

The potential of the mucoadhesive film technology is hard to ignore, owing to perceived superior patient acceptability versus buccal tablets, and significant therapeutic opportunities compared to conventional oral drug delivery systems, especially for those who suffer from dysphagia. In spite of this, current translation from published literature into the commercial marketplace is virtually non-existent, with no authorised mucoadhesive buccal films available in the UK and very few available in the USA. This review seeks to provide an overview of the mucoadhesive buccal film technology and identify key areas upon which to focus scientific efforts to facilitate the wider adoption of this patient-centric dosage form. Several indications and opportunities for development were identified, while discussing the patient-related factors influencing the use of these dosage forms. In addition, an overview of the technologies behind the manufacturing of these films was provided, highlighting manufacturing methods like solvent casting, hot melt extrusion, inkjet printing and three-dimensional printing. Over thirty mucoadhesive polymers were identified as being used in film formulations, with details surrounding their mucoadhesive capabilities as well as their inclusion alongside other key formulation constituents provided. Lastly, the importance of physiologically relevant in vitro evaluation methodologies was emphasised, which seek to improve in vivo correlations, potentially leading to better translation of mucoadhesive buccal films from the literature into the commercial marketplace.

Design and optimization of pH-sensitive Eudragit nanoparticles for improved oral delivery of triclabendazole

Design of Experiments (DoE) techniques were used to identify and optimize the parameters involved in the formulation of triclabendazole pH-sensitive Eudragit® nanoparticles (NPs). Using a Placket Burmann design, Eudragit® E, Eudragit® RS, and two stabilizers (PVP and PVA) were evaluated for NPs formulation by nanoprecipitation. Based on the screening results, Eudragit E 100® and PVP were selected as excipients, and their levels were studied and optimized using a central composite design, obtaining an optimum nanoparticulated system with a Size of 240 nm, a PDI of 0.420, and a ZP of 46.3 mV. Finally, a full characterization of the optimum system was carried out by XRD, DSC, equilibrium solubility, and dissolution rate in biorelevant mediums. As observed in XRD and DSC, the nanoencapsulation process produced a remarkable reduction in drug crystallinity that improved drug solubility and dissolution rate. Although more than 90% of TCBZ was dissolved in acidic mediums at 10 minutes, no increase in solubility or dissolution rate was observed in simulated saliva. Consequently, the development of pH-sensitive Eudragit® NPs would be a promising strategy in developing an immediate gastric release TCBZ formulation for oral delivery.

Bitter taste in silico: A review on virtual ligand screening and characterization methods for TAS2R-bitterant interactions

The growing pharmaceutical interest in the human bitter taste receptors (hTAS2Rs) has two dimensions; i) evaluation of the bitterness of active pharmaceutical compounds, in order to develop strategies for improving patients' adherence to medication, and ii) application of ligands for extra-cellular hTAS2Rs for potential preventive therapeutic achievements. The result is an increasing demand on robust tools for bitterness assessment and screening the receptor-ligand affinity. In silico tools are useful for aiding experimental-screening, as well as to elucide ligand-receptor interactions. In this review, the ligand-based and structure-based approaches are described as the two main in silico tools for bitter taste analysis. The strengths and weaknesses of each approach are discussed. Both approaches provide key tools for understanding and exploiting bitter taste for human health applications.

Quaternary enteric solid dispersion prepared by hot-melt extrusion to mask the bitter taste and enhance drug stability

To mask the bitterness of drug is profoundly important especially in children's medication. This study designed and investigated a quaternary enteric solid dispersion (QESD) by secondary hot-melt-extrusion. Erythromycin (EM) was chosen as a model drug. The optimal QESD contained enteric polymer HPMCP-55, plasticizer and water-soluble polymer copovidone VA64. Raman and Atomic force microscope has exploited that majority EM was distributed in VA64 matrix, nanometer-sized EM-VA64 system was entrapped within enteric continuous phase to form a solid emulsion-like structure. For the prepared QESD, EM released concentration was far less than bitterness threshold (7 μg/mL to 20 μg/mL) in artificial saliva within the first 30 s. And dissolution rate was increased by 10% in article intestine fluid, which dominated by water-soluble VA64. Stress testing after two months at high-humidity (75% RH) and high-temperature (60 °C) revealed, compared with traditional enteric SDs, the chemical degradation of EM was slowed down in QESD. Furthermore, hydrogen and salt bonds were respectively formed between EM and VA64 and between leaking EM and HPMCP-55, which increasing the system stability and taste-masking. The effect of masking bitter taste can be satisfied as well as enhance drug dissolution rate in the intestine, and formulation physicochemical stability during storage.

The use of electronic tongue and sensory panel on taste evaluation of pediatric medicines: a systematic review

The palatability of medications is an essential factor for children's adherence to drug treatment. Several methods for drug taste assessment have been developed. The aim of this review is to explore the literature reports of the main methods for the evaluation of medicines taste, named electronic tongue (e-tongue, in vitro) and human sensory panel. A systematic search was performed up to March 2020 and a total of 88 articles were selected. The e-tongue (57.5%) has been more frequently described than the sensory panel (10.3%), while some articles (32.2%) used both techniques. 74.7% of the articles mentioned 'pediatric', 'paediatric' or 'children' in the text, but only 19.5% developed formulations targeting pediatric audience and sensory testing in children is rarely seen. The e-tongue has predominance of use in the taste evaluation of pediatric medicines probably since it is fast, easy to perform and risk free, besides presenting less imprecise data and no fatigue. The human panel is more realistic, despite its intrinsic variability. In this sense, it is proposed the use of e-tongue as a fast way to select the most promising sample(s) and, after that, the sensory panel should be applied in order to confirm the taste masking.

Quality Control of Heparin Injections: Comparison of Four Established Methods

Heparin is an anticoagulant medication that is usually injected subcutaneously. The quality of a set of commercial heparin injections from different producers was examined by NMR, IR, UV-Vis spectroscopies and potentiometric multisensor system. The type of raw material regarding heparin animal origin and producer, heparin molecular weight and activity values were derived based on the non-targeted analysis of 1H NMR fingerprints. DOSY NMR spectroscopy was additionally used to study homogeneity and additives profile. UV-Vis and IR, being cheaper than NMR, combined with multivariate statistics were successfully applied to study excipients composition as well as semi-estimation of activity values. Potentiometric multisensor measurements were found to be an important additional source of information about inorganic composition of finished heparin formulations. All investigated instrumental techniques are useful for finished heparin injections and should be selected according to availability as well as the information and confidence required for a specific sample.

Distinguishing paracetamol formulations: Comparison of potentiometric "Electronic Tongue" with established analytical techniques

Fast and inexpensive analytical tools for identification of the origin of pharmaceutical formulations are important to ensure consumers safety. This study explores the potential of potentiometric multisensor systems ("electronic tongues") in this type of application. 72 paracetamol samples purchased in different countries and produced by various companies were studied via infrared spectroscopy (IR), near infrared spectroscopy (NIR), nuclear magnetic resonance spectroscopy (NMR) and multisensor system (ET). A variety of chemometric tools was applied to explore and compare the information yielded by these methods. It was found that ET is capable of distinguishing paracetamol formulations from different producers. The chemical information derived from potentiometric sensor responses has something in common with that derived from NIR and IR; however, it is orthogonal to that from NMR. ET can be a valuable tool in express quality assessment of drugs.

Multisensor Systems and Arrays for Medical Applications Employing Naturally-Occurring Compounds and Materials

The significant improvement of quality of life achieved over the last decades has stimulated the development of new approaches in medicine to take into account the personal needs of each patient. Precision medicine, providing healthcare customization, opens new horizons in the diagnosis, treatment and prevention of numerous diseases. As a consequence, there is a growing demand for novel analytical devices and methods capable of addressing the challenges of precision medicine. For example, various types of sensors or their arrays are highly suitable for simultaneous monitoring of multiple analytes in complex biological media in order to obtain more information about the health status of a patient or to follow the treatment process. Besides, the development of sustainable sensors based on natural chemicals allows reducing their environmental impact. This review is concerned with the application of such analytical platforms in various areas of medicine: analysis of body fluids, wearable sensors, drug manufacturing and screening. The importance and role of naturally-occurring compounds in the development of electrochemical multisensor systems and arrays are discussed.

Critical Evaluation of Laboratory Potentiometric Electronic Tongues for Pharmaceutical Analysis-An Overview

Electronic tongue systems equipped with cross-sensitive potentiometric sensors have been applied to pharmaceutical analysis, due to the possibility of various applications and developing new formulations. Many studies already proved the complementarity between the electronic tongue and classical analysis such as dissolution tests indicated by Pharmacopeias. However, as a new approach to study pharmaceuticals, electronic tongues lack strict testing protocols and specification limits; therefore, their results can be improperly interpreted and inconsistent with the reference studies. Therefore, all aspects of the development, measurement conditions, data analysis, and interpretation of electronic tongue results were discussed in this overview. The critical evaluation of the effectiveness and reliability of constructed devices may be helpful for a better understanding of electronic tongue systems development and for providing strict testing protocols.

Critical review of electronic nose and tongue instruments prospects in pharmaceutical analysis

Electronic nose (enose, EN) and electronic tongue (etongue, ET) have been designed to simulate human senses of smell and taste in the best possible way. The signals acquired from a sensor array, combined with suitable data analysis system, are the basis for holistic analysis of samples. The efficiency of these instruments, regarding classification, discrimination, detection, monitoring and analytics of samples in different types of matrices, is utilized in many fields of science and industry, offering numerous practical applications. Popularity of both types of devices significantly increased during the last decade, mainly due to improvement of their sensitivity and selectivity. The electronic senses have been employed in pharmaceutical sciences for, among others, formulation development and quality assurance. This paper contains a review of some particular applications of EN and ET based instruments in pharmaceutical industry. In addition, development prospects and a critical summary of the state of art in the field were also surveyed.

Creation of an assessment system for measuring the bitterness of azithromycin-containing reverse micelles

We aimed to develop a novel method for assessing the bitterness of azithromycin-containing reverse micelles (AM-containing RMs). Azithromycin-containing reverse micelles were prepared by processing Lipoid E80 and medium chain triglycerides via a freeze-drying method. The bitterness threshold of azithromycin was determined by human taste test, and an equation was derived to correlate the azithromycin concentrations and bitterness scores of standard solutions. Simulated salivary fluids and sampling times were fixed based on the drug release profile of AM-containing RMs, with Zithromax^® (a commercial formulation of azithromycin) used as the control. The drug release concentrations from stimulated salivary fluids were then used to assess the bitterness of AM-containing RMs and Zithromax^®. Afterward, the oral bioavailability of both formulations was evaluated by in vivo experiments in male Wistar rats. The results showed that the bitterness threshold of azithromycin standard solutions was between 25.3 µg/ml and 30.4 µg/ml. Thereafter, we calculated that the bitterness scores and the drug release concentrations of the azithromycin-containing reverse micelle formulation were similar to those of Zithromax^® at each time point after 10 min of dispersal in simulated salivary fluid. In addition, the AUC_0−t after oral administration of AM-containing RMs was 1.75-fold (P < 0.05) higher than that of Zithromax^®. In conclusions, a system for assessing bitterness was developed using an in vitro drug release evaluation method and a human taste test panel. We found that the bitterness of azithromycin was successfully masked by reverse micelles, which also improved the oral bioavailability of azithromycin compared to that of Zithromax^®.