Stability, Dose Uniformity, and Palatability of Three Counterterrorism Drugs—Human Subject and Electronic Tongue Studies

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.

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.

Taste masking of water-soluble drug by solid lipid microspheres: a child-friendly system established by reversed lipid-based nanoparticle technique

Objectives

A child-friendly taste-masking strategy using solid lipid microsphere (SLM) has been proposed to obscure the undesirable taste of some water-soluble drugs. In this study, the reversed lipid-based nanoparticle (RLBN) technique was used to encapsulate a water-soluble drug to facilitate the preparation of SLM.

Methods

The model drug used was atomoxetine hydrochloride (ATX), and a three-step method was used to prepare ATX-RLBN. Taste-masking microsphere (ATX-RLBN-SLM) was prepared by the spray chilling method. The drug release mechanism was studied by high-performance liquid chromatography and scanning electron microscopy. Moreover, in vitro taste evaluation method was established and ATX bioavailability was investigated employing pharmacokinetic studies.

Key findings

The obtained ATX-RLBN-SLM had smooth spherical particles with a size of about 80 μm. The drug encapsulation and loading efficiencies were 98.28% ± 0.59% and 0.89% ± 0.04%, respectively. In vitro drug release studies showed that nearly 96% drug was retained in the microspheres within 10 min at pH 6.8 and a complete release was triggered by lipase, accompanied by variation in the morphology. Taste assessment revealed that ATX-RLBN-SLM could efficiently mask the bitter taste and improved the bioavailability of ATX.

Conclusions

Atomoxetine hydrochloride-reversed lipid-based nanoparticle-solid lipid microsphere exhibited excellent taste-masking effect with negligible leakage in the oral cavity environment and thorough collapse upon lipase stimulation, simultaneously enhancing the bioavailability of ATX. The study paves a new way to efficiently mask the undesirable taste of some water-soluble drugs.

Electronic Tongue-A Tool for All Tastes?

Electronic tongue systems are traditionally used to analyse: food products, water samples and taste masking technologies for pharmaceuticals. In principle, their applications are almost limitless, as they are able to almost completely reduce the impact of interferents and can be applied to distinguish samples of extreme complexity as for example broths from different stages of fermentation. Nevertheless, their applications outside the three principal sample types are, in comparison, rather scarce. In this review, we would like to take a closer look on what are real capabilities of electronic tongue systems, what can be achieved using mixed sensor arrays and by introduction of biosensors or molecularly imprinted polymers in the matrix. We will discuss future directions both in the sense of applications as well as system development in the ever-growing trend of low cost analysis.

Suitability of E-tongue Sensors to Assess Taste-Masking of Pediatric Liquids by Different Beverages Considering Their Physico-chemical Properties

Manipulation of liquid oral drugs by mixing them into foodstuff is a common procedure for taste-masking of OTC pharmaceuticals when administered to children. However, the taste-masking capability of such application media is not systematically evaluated, and recommendations for suitable media are hardly published. In this study, a sensor array of commercially available and self-developed electronic tongue sensors was employed to assess the taste-masking efficiency of eight different beverages (tap water, apple juice, carrot juice, fennel tea, fruit tea, milk, cocoa, and Alete meal to drink) on the OTC pharmaceuticals Ambroxol-ratiopharm®, Cetirizin AL, and Laxoberal® by multivariate data analysis. The Euclidean distances between each pure application medium and its corresponding drug mixture were used as an indicator for the taste-masking efficiency and correlated to the physico-chemical properties of the beverages. Thus, the pH value, the viscosity, as well as the fat and sugar content of the beverages were included, whereas only the viscosity appeared to be insignificant in all cases. The sugar content as well as the fat content and pH value emerged to be a significant variable in taste-masking efficiency for some of the tested drug products. It was shown that the applied electronic tongue sensors were capable to demonstrate the impact of the physico-chemical properties of the application media on their taste-masking capacity regardless of their non-selectivity towards these characteristics.

Qualitative and quantitative analysis of fatty acid profiles of Chinese pecans (Carya cathayensis) during storage using an electronic nose combined with chemometric methods

Chinese pecans (Carya cathayensis) continuously deteriorate during storage because of their high fatty acid contents.

The fungicide triadimefon affects beer flavor and composition by influencing Saccharomyces cerevisiae metabolism

Despite the fact that beer is produced on a large scale, the effects of pesticide residues on beer have been rarely investigated. In this study, we used micro-brewing settings to determine the effect of triadimefon on the growth of Saccharomyces cerevisiae and beer flavor. The yeast growth in medium was significantly inhibited (45%) at concentrations higher than 5 mg L(-1), reaching 80% and 100% inhibition at 10 mg L(-1) and 50 mg L(-1), respectively. There were significant differences in sensory quality between beer samples fermented with and without triadimefon based on data obtained with an electronic tongue and nose. Such an effect was most likely underlain by changes in yeast fermentation activity, including decreased utilization of maltotriose and most amino acids, reduced production of isobutyl and isoamyl alcohols, and increased ethyl acetate content in the fungicide treated samples. Furthermore, yeast metabolic profiling by phenotype microarray and UPLC/TOF-MS showed that triadimefon caused significant changes in the metabolism of glutathione, phenylalanine and sphingolipids, and in sterol biosynthesis. Thus, triadimefon negatively affects beer sensory qualities by influencing the metabolic activity of S. cerevisiae during fermentation, emphasizing the necessity of stricter control over fungicide residues in brewing by the food industry.

Early detection of Zygosaccharomyces rouxii--spawned spoilage in apple juice by electronic nose combined with chemometrics

Spoilage spawned by Zygosaccharomyces rouxii can cause sensory defect in apple juice, which could hardly be perceived in the early stage and therefore would lead to the serious economic loss. Thus, it is essential to detect the contamination in early stage to avoid costly waste of products or recalls. In this work the performance of an electronic nose (e-nose) coupled with chemometric analysis was evaluated for diagnosis of the contamination in apple juice, using test panel evaluation as reference. The feasibility of using e-nose responses to predict the spoilage level of apple juice was also evaluated. Coupled with linear discriminant analysis (LDA), detection of the contamination was achieved after 12h, corresponding to the cell concentration of less than 2.0 log 10 CFU/mL, the level at which the test panelists could not yet identify the contamination, indicating that the signals of e-nose could be utilized as early indicators for the onset of contamination. Loading analysis indicated that sensors 2, 6, 7 and 8 were the most important in the detection of Z. rouxii-contaminated apple juice. Moreover, Z. rouxii counts in unknown samples could be well predicted by the established models using partial least squares (PLS) algorithm with high correlation coefficient (R) of 0.98 (Z. rouxii strain ATCC 2623 and ATCC 8383) and 0.97 (Z. rouxii strain B-WHX-12-53). Based on these results, e-nose appears to be promising for rapid analysis of the odor in apple juice during processing or on the shelf to realize the early detection of potential contamination caused by Z. rouxii strains.

Orally disintegrating films and mini-tablets-innovative dosage forms of choice for pediatric use

Oral drug delivery is a non-invasive and therefore a very convenient route of administration. Orally disintegrating dosage forms, like soluble films and (mini-)tablets, appear promising for use in the pediatric population. New guidance for the development of pediatric medicines has been published, which provides considerations on how pediatric products should be designed. However, most of the considerations leave a lot of room for interpretations. Bearing in mind the different aspects discussed in the latest guideline, the use of orally disintegrating films and tablets, in particular, small-sized tablets, is discussed and reflected upon by providing evidence from the scientific literature. The available dosage forms for children are various and examples of currently licensed products for use in the pediatric population were compiled. Aspects such as the appropriateness for pediatrics, the choice of excipients, the opportunities for modified drug release preparations or fixed-dose combinations, the acceptability and palatability, and also limitations were discussed with respect to the new dosage forms of orally disintegrating films and mini-tablets. This paper points out that innovation in pediatric medicines are planned and should be encouraged; however, supported by the regulatory guidance, only general considerations are provided. Nevertheless, the guideline summarizes multiple points to consider during the development of medicines for pediatric use. Considering the scientific evidence and the regulatory guidance, orally disintegrating dosage forms, like soluble films and (mini-)tablets, offer an innovative solution for pediatric drug delivery.

Determination of rice sensory quality with similarity analysis-artificial neural network method in electronic tongue system

A novel similarity analysis-artificial neural network method was developed in electronic tongue system for predicting rice sensory quality.

Discrimination and characterization of strawberry juice based on electronic nose and tongue: comparison of different juice processing approaches by LDA, PLSR, RF, and SVM

An electronic nose (E-nose) and an electronic tongue (E-tongue) have been used to characterize five types of strawberry juices based on processing approaches (i.e., microwave pasteurization, steam blanching, high temperature short time pasteurization, frozen-thawed, and freshly squeezed). Juice quality parameters (vitamin C, pH, total soluble solid, total acid, and sugar/acid ratio) were detected by traditional measuring methods. Multivariate statistical methods (linear discriminant analysis (LDA) and partial least squares regression (PLSR)) and neural networks (Random Forest (RF) and Support Vector Machines) were employed to qualitative classification and quantitative regression. E-tongue system reached higher accuracy rates than E-nose did, and the simultaneous utilization did have an advantage in LDA classification and PLSR regression. According to cross-validation, RF has shown outstanding and indisputable performances in the qualitative and quantitative analysis. This work indicates that the simultaneous utilization of E-nose and E-tongue can discriminate processed fruit juices and predict quality parameters successfully for the beverage industry.

Taste-masking assessment of solid oral dosage forms--a critical review

Approaches to improve the taste of oral dosage forms that contain unpleasant tasting drugs are versatile. Likewise, the analytical in vitro and in vivo methods to assess taste-masking efficacy are diverse. Taste-masking has gained in importance since the EU legislation on medicines for children came into force in 2007, and taste-masking attributes are often required by regulatory authorities. However, standardized guidance for the analytical evaluation is still poor. Published protocols rarely consider real conditions, such as the volume of saliva or the residence time of solid oral dosage forms in the mouth. Methodological limitations and problems regarding time point of evaluation, sampling or sample pretreatment are hardly ever addressed. This critical review aims to evaluate and discuss published strategies in this context.

Doxycycline concentration over time after storage in a compounded veterinary preparation

OBJECTIVE

To determine the concentration of doxycycline compounded from doxycycline hyclate tablets into liquid formulations for oral administration in veterinary species and stored for 28 days.

DESIGN

Evaluation study.

SAMPLE

Doxycycline hyclate tablets (100 mg) crushed and mixed with a 50:50 mixture of syrup and suspension vehicles for oral administration to produce 3 batches each of 2 doxycycline formulations: 33.3 and 166.7 mg/mL.

PROCEDURES

Formulations were stored, protected from light, at room temperature (22° to 26°C [71.6° to 78.8°F]) and at a controlled cold temperature (refrigerated 2° to 8°C [35.6° to 46.4°F]). Doxycycline was extracted from the formulations, and concentration was measured by high-pressure liquid chromatography on days 0 (date of preparation), 1, 4, 7, 14, 21, and 28. Concentrations were compared with those of a US Pharmacopeial Convention reference standard. Formulation quality at each point was also assessed through color change, formulation consistency, and suspension uniformity.

RESULTS

On days 0, 1, 4, and 7, the concentration of each formulation was within 90% to 110% of the reference standard (range, 93% to 109%), which was deemed acceptable. However, doxycycline concentrations had decreased dramatically by day 14 and remained low for the duration of the study period. Doxycycline concentrations on days 14, 21, and 28 were all < 20% (range, 14% to 18%) of the reference standard, and the quality of the formulations decreased as well. No effect of storage temperatures on doxycycline concentration was identified.

CONCLUSIONS AND CLINICAL RELEVANCE

The concentration of doxycycline, compounded from commercial tablets in the vehicles evaluated to yield doses of 33.3 and 166.7 mg/mL, cannot be assured beyond 7 days.

The bad taste of medicines: overview of basic research on bitter taste

BACKGROUND

Many active pharmaceutical ingredients taste bitter and thus are aversive to children as well as many adults. Encapsulation of the medicine in pill or tablet form, an effective method for adults to avoid the unpleasant taste, is problematic for children. Many children cannot or will not swallow solid dose forms.

OBJECTIVE

This review highlights basic principles of gustatory function, with a special focus on the science of bitter taste, derived from studies of animal models and human psychophysics. We focus on the set of genes that encode the proteins that function as bitter receptors as well as the cascade of events that leads to multidimensional aspects of taste function, highlighting the role that animal models played in these discoveries. We also summarize psychophysical approaches to studying bitter taste in adult and pediatric populations, highlighting evidence of the similarities and differences in bitter taste perception and acceptance between adults and children and drawing on useful strategies from animal models.

RESULTS

Medicine often tastes bitter, and because children are more bitter-sensitive than are adults, this creates problems with compliance. Bitter arises from stimulating receptors in taste receptor cells, with signals processed in the taste bud and relayed to the brain. However, there are many gaps in our understanding of how best to measure bitterness and how to ameliorate it, including whether it is more efficiently addressed at the level of receptor and sensory signaling, at the level of central processing, or by masking techniques. All methods of measuring responsiveness to bitter ligands-in animal models through human psychophysics or with "electronic tongues"-have limitations.

CONCLUSIONS

Better-tasting medications may enhance pediatric adherence to drug therapy. Sugars, acids, salt, and other substances reduce perceived bitterness of several pharmaceuticals, and although pleasant flavorings may help children consume some medicines, they often are not effective in suppressing bitter tastes. Further development of psychophysical tools for children will help us better understand their sensory worlds. Multiple testing strategies will help us refine methods to assess acceptance and compliance by various pediatric populations. Research involving animal models, in which the gustatory system can be more invasively manipulated, can elucidate mechanisms, ultimately providing potential targets. These approaches, combined with new technologies and guided by findings from clinical studies, will potentially lead to effective ways to enhance drug acceptance and compliance in pediatric populations.

Taste sensing systems (electronic tongues) for pharmaceutical applications

Electronic tongues are sensor array systems able to detect single substances as well as complex mixtures by means of particular sensor membranes and electrochemical techniques. Two systems are already commercially available, the Insent taste sensing system and the αAstree electronic tongue. In addition, various laboratory prototype versions exist. Besides the successful use in food industry, the implementation for pharmaceutical purposes has strongly grown within the recent years. A reason for this is the increased interest of developing palatable formulations, especially for children. As taste assessment of drugs comes along with challenges due to possible toxicity and subjectivity of the taste assessors, electronic tongues could offer a safe and objective alternative. In order to provide guidance on the use of these systems, possible fields of interest are presented in this review, as for example, system qualification, quality control, formulation development, comparison between marketed drug products, and the validation of the methods used. Further, different approaches for solid and liquid dosage forms are summarized. But, also the difficulty to obtain absolute statements regarding taste was identified and the need of more validated data was discussed to offer guidance for the next years of research and application of electronic tongues for pharmaceutical applications.

Recent advances in electronic tongues

This minireview describes the main developments of electronic tongues (e-tongues) and taste sensors in recent years, with a summary of the principles of detection and materials used in the sensing units. E-tongues are sensor arrays capable of distinguishing very similar liquids employing the concept of global selectivity, where the difference in the electrical response of different materials serves as a fingerprint for the analysed sample. They have been widely used for the analysis of wines, fruit juices, coffee, milk and beverages, in addition to the detection of trace amounts of impurities or pollutants in waters. Among the various principles of detection, electrochemical measurements and impedance spectroscopy are the most prominent. With regard to the materials for the sensing units, in most cases use is made of ultrathin films produced in a layer-by-layer fashion to yield higher sensitivity with the advantage of control of the film molecular architecture. The concept of e-tongues has been extended to biosensing by using sensing units capable of molecular recognition, as in films with immobilized antigens or enzymes with specific recognition for clinical diagnosis. Because the identification of samples is basically a classification task, there has been a trend to use artificial intelligence and information visualization methods to enhance the performance of e-tongues.

An electronic tongue: evaluation of the masking efficacy of sweetening and/or flavoring agents on the bitter taste of epinephrine

An epinephrine (E) tablet is under development for sublingual (SL) administration for the first-aid treatment of anaphylaxis; however, the inherent bitterness of E may hinder acceptability by patients, especially children. To assess the degree of E bitterness and to predict the masking effects of sweetening and/or flavoring non-medicinal ingredients (NMIs), the potential usefulness of an electronic tongue (e-Tongue) was evaluated. The e-Tongue sensors were conditioned, calibrated, and tested for taste discrimination. Six standard active pharmaceutical ingredients were used to build and validate a bitterness model which was then used to assess E bitartrate (EB) solutions from 0.3-9 mM. Taste-masking efficiency of aspartame (ASP), acesulfame potassium (ASK), and citric acid (CA) each at 0.5 mM was evaluated. Using EB 9 mM, the bitterness score was 20 on a scale of 20 (unacceptable) down to 1 (not detected). When NMIs 0.5 mM were added, neither ASK (17.2, unacceptable) nor was ASP (14.0, limit acceptable) effective in masking the bitter taste. When the combination of ASK and ASP was used, the bitterness score was reduced to 9.2 (acceptable). However, the addition of CA alone resulted in the best reduction of the bitterness score to 3.3 (not detected). Using the e-Tongue, the incorporation of a variety of sweetening and/or flavoring NMIs into a SL tablet of E could be shown to mask its bitter taste by up to 80%. These results should be confirmed by in vivo studies.

Oseltamivir compounding in the hospital pharmacy during the (H1N1) influenza pandemic

AIMS

Pandemics impose large demands on the health care system. The supply of appropriate chemotherapeutic agents, namely oseltamivir solution, presented a serious challenge in the recent influenza pandemic. This study reports on the rational series of pharmacotechnical steps that were followed to appropriately handle bulk oseltamivir powder to meet the increased demand.

METHODS

During a six-week period in August and September of 2009, a task force was created in the Central Pharmacy of Hospital das Clínicas to convert imported oseltamivir phosphate into ready-to-use solution for utilization by physicians and public health authorities. The protocol included dissolution, physico-chemical tests and the bottling of a liquid microdose formulation for emergency room and outpatient dispensing with adequate quality control during all phases.

RESULTS

The successful production routine was based on a specially designed flowchart according to which a batch of 33210 g of oseltamivir powder was converted into 32175 solution units during the aforementioned period with a net loss of only 2.6%. The end products were bottles containing 50 ml of 15 mg/mL oseltamivir solution. The measured concentration was stable and accurate (97.5% - 102.0% of the nominal value). The drug was prescribed as both a prophylactic and therapeutic agent.

DISCUSSION

Hospital pharmacies are conventionally engaged in the manipulation of medical prescriptions and specialty drugs. They are generally responsible for only small-scale equipment used for manufacturing and quality-control procedures. The compounding of oseltamivir was a unique effort dictated by exceptional circumstances.

CONCLUSION

The shortage of oseltamivir solution for clinical use was solved by emergency operationalization of a semi-industrial process in which bulk powder was converted into practical vials for prompt delivery.

Chemometric brains for artificial tongues

The last years showed a significant trend toward the exploitation of rapid and economic analytical devices able to provide multiple information about samples. Among these, the so-called artificial tongues represent effective tools which allow a global sample characterization comparable to a fingerprint. Born as taste sensors for food evaluation, such devices proved to be useful for a wider number of purposes. In this review, a critical overview of artificial tongue applications over the last decade is outlined. In particular, the focus is centered on the chemometric techniques, which allow the extraction of valuable information from nonspecific data. The basic steps of signal processing and pattern recognition are discussed and the principal chemometric techniques are described in detail, highlighting benefits and drawbacks of each one. Furthermore, some novel methods recently introduced and particularly suitable for artificial tongue data are presented.

Optimizing oral medications for children

BACKGROUND

Active pharmaceutical ingredients that taste bitter and/or irritate the mouth and throat are aversive to children as well as many adults. Effective methods of avoiding unpleasant tastes for adults (eg, encapsulating the medicine in pill, capsule, or tablet form) are problematic because many children cannot or will not swallow these. The unpalatable flavor of the medicine can thwart the benefits of even the most powerful of drugs. Failure to consume medication may do the child harm and can even be life-threatening.

OBJECTIVES

This article provides an overview of the current knowledge of the sensory capabilities and preferences of children as it relates to flavor, defined here as the combined input of taste, smell, and chemical irritation. The methods used to evaluate flavor perception in children are reviewed. Recent scientific advances are summarized that shed light on why the bitter taste of oral pharmaceuticals is an ongoing formulation problem and how discoveries of novel flavor molecules and modulators of bitter tastes hold considerable promise for the future. Alternative methods for evaluation of the palatability of medicines are described.

METHODS

The Eunice Kennedy Shriver National Institute of Child Health and Human Development sponsored a Pediatric Formulation Initiative workshop on December 6 and 7, 2005, in Bethesda, Maryland. Information for this article was gathered from literature reviews that were then discussed during this workshop as well as during several conference calls with the Taste and Flavor Working Group members. Terms for the MEDLINE search (1970-2007) included infant, children, taste, olfaction/smell, flavor, chemical senses, palatability, sensory testing, pharmaceutical, and medicines.

RESULTS

Children have well-developed sensory systems for detecting tastes, smells, and chemical irritants, and their rejection of unpalatable medications is a reflection of their basic biology. Sugars, salt, and other substances reportedly reduce the bitterness of several pharmaceuticals. Adding pleasant flavor volatiles such as bubble gum may help induce children to consume a medicine, but such volatile compounds are not effective in suppressing the strong bitter tastes associated with some medications. Also, because individual experiences and culture mainly determine which odors are attractive, a universally appealing volatile flavoring agent may be difficult to identify. Sensory panelists who are sensitive to the pediatric palate, which is different from adults, and new techniques involving animal models, isolated parts of the receptor cells, and even electronic devices that detect taste and flavor are among the tools that may be used to evaluate the palatability of medications and predict compliance among pediatric populations.

CONCLUSIONS

Although there are no easy solutions to this dilemma, children's acceptance of many medicines can be improved by applying the knowledge gleaned from basic research in the chemical senses. Further development and validation of sensory methods will provide a better understanding of the sensory world of the child. This understanding, combined with new technologies and results of animal model studies, will enhance drug acceptance and compliance in pediatric populations. A better understanding of the scientific basis for distaste and how to ameliorate it is a public health priority.

Evaluation of a taste sensor instrument (electronic tongue) for use in formulation development

A taste sensor instrument (electronic tongue) was evaluated to determine its utility in developing a taste-enhanced liquid formulation. To train the electronic tongue, human sensory panel data were collected for two prototype formulations, a solution of the drug in water and several marketed products. Studies using the electronic tongue were conducted to determine taste-masking effectiveness of formulations compared to a matching placebo, to establish correlation with human sensory data, and to evaluate unknown formulations and predict their bitterness scores. In the first experiment, the effectiveness of a proposed taste-masking strategy was determined by comparing formulation prototypes containing a bitter active pharmaceutical ingredient (API) against corresponding placebos (i.e. formulations without an active ingredient) using electronic tongue data. The analysis of the electronic tongue data was based on the assumption that the drug was well taste masked if the placebo matched the formulation with API. In a second set of experiments, electronic tongue data were compared to existing data from a human taste panel for several marketed products and prototype formulations. A good correlation (r(2)=0.99) was achieved from this comparison, and the relative taste of prototype formulations not tasted by humans was predicted.

Electronic integrated multisensor tongue applied to grape juice and wine analysis

An integrated multisensor composed by six ISFET devices selective to common ions and heavy metals combined with a flow injection analysis (FIA) system has been applied as an electronic tongue to grape juice and wine sample analysis. The data obtained for several grape and wine variety samples analysis have been treated using multiparametric tools like principal component analysis (PCA) and soft independent modelling class analogy technique (SIMCA) for the patterning recognition and classification of samples and partial least squares (PLS) regression for quantification of several parameters of interest in wine production. The results obtained have demonstrated the potential of using those multisensors as electronic tongues not only for distinguishing the samples according to the grape variety and the vintage year but also for quantitative prediction of several sample parameters.

Sensor arrays for liquid sensing--electronic tongue systems

Electronic tongue systems are multisensor devices dedicated to automatic analysis of complicated composition samples and to the recognition of their characteristic properties. Recently, the number of publications covering this topic has significantly increased. Many possible architectures of such devices were proposed: potentiometric, voltammetric, as well as approaches embracing mass- and optical-sensors. For the analysis of sensor array data, various pattern recognition systems were proposed. All of these topics are summarized in this review. Moreover, additional problems are considered: miniaturization of electronic tongues and hybrid systems for liquid sensing.

The latest trends in the taste assessment of pharmaceuticals

To date, the most widely used method for measuring the taste characteristics of pharmaceutical preparations is psychophysical evaluation by a taste panel. However, conventional chemical analyses, on the basis of release studies, have been shown to be useful subsidiary methods. More recently, novel in vitro taste assessment apparatus and methodologies have been developed for high-throughput taste screening and quality control. Biomimetic taste sensing systems (BMTSSs), such as multichannel taste sensors or electronic tongues with global selectivity, have been welcomed by both pharmaceutical scientists and the industry as a whole. As we discuss here, the emerging in vitro approaches for assessing taste characteristics of taste masked drug and drug products will result in a decreased reliance on human panel tests.