Taste-masking properties of solid lipid based micropellets obtained by cold extrusion-spheronization

Taste-masking methods in multiparticulate dosage forms with a focus on poorly soluble drugs

In the past, the administration of medicines for children mainly involved changes to adult dosage forms, such as crushing tablets or opening capsules. However, these methods often led to inconsistent dosing, resulting in under- or overdosing. To address this problem and promote adherence, numerous initiatives, and regulatory frameworks have been developed to develop more child-friendly dosage forms. In recent years, multiparticulate dosage forms such as mini-tablets, pellets, and granules have gained popularity. However, a major challenge that persists is effectively masking the bitter taste of drugs in such formulations. This review therefore provides a brief overview of the current state of the art in taste masking techniques, with a particular focus on taste masking by film coating. Methods for evaluating the effectiveness of taste masking are also discussed and commented on. Another important issue that arises frequently in this area is achieving sufficient dissolution of poorly water-soluble drugs. Since the simultaneous combination of sufficient dissolution and taste masking is particularly challenging, the second objective of this review is to provide a critical summary of studies dealing with multiparticulate formulations that are tackling both of these issues.

Role of Nanotechnology in Taste Masking: Recent Updates

One of the important parameters in the case of dosage form is taste. Most of the drugs available in oral dosage form have an unpleasant taste which leads to patient incompliance and affects the success ratio of products in the market. Geriatric and paediatric patients suffer more with the bitter taste of medicines. According to the studies reported, it is found that 50% of the population have the problem swallowing tablets, especially the pediatric and geriatric population. Masking the taste of bitter drugs has become necessary in the pharmaceutical field and increasing interest of researchers to develop various methods for masking the bitter taste of drugs. Five major tastes, felt by our tongue are salt, sour, sweet, bitter, and umami. When the drug dissolves with saliva, drug molecules interact with taste receptors present on the tongue and give taste sensations. Although, many solid oral dosage forms like pills, and tablets have an additional advantage of masking and encapsulation of bitter taste drugs; however, they might not be effective for children because they may or may not swallow pills or tablets. There are various other methods that mask the bitter taste of drugs such as the addition of sweeteners and flavouring agents, granulation, coating, inclusion complexes, extrusion method, ion-exchange resins, etc, discussed in the first section of the article. The second part of this article consists of various nanotechnology-based drug delivery systems that were fabricated by researchers to mask the bitter taste of drugs. A brief of recent literature on various nanocarriers that were fabricated or developed for taste masking has been discussed in this part. A better understanding of these methods will help researchers and pharmaceutical industries to develop novel drug delivery systems with improved taste masking properties.

Continuous Processing of Micropellets via Hot-Melt Extrusion

Microparticulate drug delivery systems, e.g., micropellets (MPs), are used in a variety of pharmaceutical formulations such as suspensions, injectable systems, and capsules. MPs are currently manufactured mainly via batch, solvent-based processes, e.g., spray-drying and solvent evaporation-extraction. In this paper, we present a novel, solvent-free, continuous hot-melt extrusion-based approach with an inline cold pelletization step and the potential of unprecedented on-the-fly formulation changes, aiming at producing the smallest particles usable for injectable applications. A biodegradable, crystalline dispersion consisting of poly(DL-lactic acid) (PLA) filled with metformin as the model drug was chosen on purpose to elucidate the broad applicability of the process also to formulations with limited stretchability and complex pelletizability. Next to optical/statistical particle analyses and in-line high-speed camera investigations providing insights into the pelletization process, the injectability of the most promising micropellets was compared to that of one marketed formulation. Fast extrudate haul-off speeds and high numbers of pelletizer knives resulted in particles with a narrow and small particle size distribution with a d₅₀ below 270 µm and aspect ratios close to 1. To omit protruding drug particles to ensure sufficient extrudate stretchability and allow for the smallest MPs, it was found that the d₉₀ of the embedded drug must be significantly below the extrudate diameter. Upon adapting the syringe diameter, the produced micropellets revealed similar injectability parameters to the marketed formulation, showcasing the potential that the proposed setup has for the manufacturing of novel microparticulate formulations.

Filament-based 3D-printing of placebo dosage forms using brittle lipid-based excipients

In order to expand the limited portfolio of available polymer-based excipients for fabricating three-dimensional (3D) printed pharmaceutical products, Lipid-based excipients (LBEs) have yet to be thoroughly investigated. The technical obstacle of LBEs application is, however their crystalline nature that renders them very brittle and challenging for processing via 3D-printing. In this work, we evaluated the functionality of LBEs for filament-based 3D-printing of oral dosage forms. Polyglycerol partial ester of palmitic acid and polyethylene glycols monostearate were selected as LBEs, based on their chemical structure, possessing polar groups for providing hydrogen-bonding sites. A fundamental understanding of structure-function relationship was built to screen the critical material attributes relevant for both extrusion and 3D-printing processes. The thermal behavior of lipids, including the degree of their supercooling, was the critical attribute for their processing. The extrudability of materials was improved through different feeding approaches, including the common powder feeding and a devised liquid feeding setup. Liquid feeding was found to be more efficient, allowing the production of filaments with high flexibility and improved printability. Filaments with superior performance were produced using polyglycerol ester of palmitic acid. In-house designed modifications of the utilized 3D-printer were essential for a flawless processing of the filaments.

Preparation and evaluation of valnemulin hydrochloride taste-masking granules

BACKGROUND

The bitter taste and strong irritation of valnemulin hydrochloride limit its wide clinical application in pigs by oral.

METHOD

In order to improve its palatability and residence time in the body, the valnemulin hydrochloride taste-masking granules with sustained-release were prepared by combining solid dispersion based on fatty acid with wet granulation. The formulation was screened by orthogonal test with content, yield, grain size and angle of repose as evaluation indexes.

RESULT

The results showed that the optimal granules were composed of corn starch, sucrose, citric acid, valnemulin hydrochloride and myristic acid at a ratio of 40: 20: 20: 11: 19. The daily feed intake of pigs in the optimum taste-masking granule groups was similar to that of its self-control, and significantly higher than that in the valnemulin hydrochloride active ingredient group, suggesting that the optimum granules have satisfactory palatability. The prepared granules improved the oral bioavailability of valnemulin hydrochloride by 3.04 folds and extended its mean residence time (MRT) by 2.33 folds.

CONCLUSION

The granules developed in this study could obviously improve the palatability and sustained release of valnemulin hydrochloride. The producing method of granules by combining solid dispersion powder with wet granulation can provide ideas for other drugs with poor palatability and a short half-life.

A New Bitterness Evaluation Index Obtained Using the Taste Sensor for 48 Active Pharmaceutical Ingredients of Pediatric Medicines

The aim of this study was to evaluate bitterness by using "CCDP; Change in concentration-dependent potential" considering dose-dependency of active pharmaceutical ingredients (APIs) as new and useful bitterness evaluation index compared with bitter sensor output value which is conventional bitterness evaluation index for 48 pediatric medicines from the recent edition of the WHO model list of essential medicines for children (7th edn, 2019). Solutions (0.01, 0.03, 0.1 mM) of the compounds were evaluated by an artificial taste sensor using membranes sensitive to bitterness. The dose-response slope of the sensor outputs was defined as CCDP. On the basis of principal component analysis of CCDPs, chlorpromazine hydrochloride, amitriptyline hydrochloride, propranolol hydrochloride, primaquine phosphate and haloperidol were predicted to express the strongest levels of basic bitterness, surpassing that of quinine hydrochloride. Correlation analysis (Fisher's exact tests and multiple regression analysis) was performed to determine the relation between CCDPs and various physicochemical properties participated in hydrophilicity and hydrophobicity. It is revealed that contribution physicochemical factors are different by individual basic bitterness sensor (AC0, AN0 or BT0), and this result becomes the criterion of the sensor choice to evaluate basic bitterness intensity using basic bitterness sensors. Hydrophobic and hydrophilic interactions could be simulated by ligand docking modeling for haloperidol, miconazole and quinine hydrochloride. The pharmaceutical products need a bitterness evaluation in consideration of concentration-dependency to vary in a dose depending on a patient individual. Thus, it was concluded that CCDP correlated to hydrophilicity and hydrophobicity is useful as a bitterness evaluation index of APIs in pediatric medicines.

Lipids for Taste masking and Taste assessment in pharmaceutical formulations

Pharmaceutical products often have drawbacks of unacceptable taste and palatability which makes it quite difficult for oral administration to some special populations like pediatrics and geriatrics. To curb this issue different approaches like coating, granulation, extrusion, inclusion complexation, ion-exchange resins, etc for taste masking are employed and among them use of lipids have drawn special attention of researchers. Lipids have a lower melting point which is ideal for incorporating drugs in some of these methods like hot-melt extrusion, melt granulation, spray drying/congealing and emulsification. Lipids play a significant role as a barrier to sustain the release of drugs and biocompatible nature of lipids increases their acceptability by the human body. Further, lipids provide vast opportunities of altering pharmacokinetics of the active ingredients by modulating release profiles. In taste sensors, also known as electronic tongue or e-tongue, lipids are used in preparing taste sensing membranes which are subsequently used in preparing taste sensors. Lipid membrane taste sensors have been widely used in assessing taste and palatability of pharmaceutical and food formulations. This review explores applications of lipids in masking the bitter taste in pharmaceutical formulations and significant role of lipids in evaluation of taste and palatability.

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.

Fabrication of Taste-Masked Donut-Shaped Tablets Via Fused Filament Fabrication 3D Printing Paired with Hot-Melt Extrusion Techniques

The objective of this work was to develop taste-masked donut-shaped tablet formulations utilizing fused filament fabrication three-dimensional printing paired with hot-melt extrusion techniques. Caffeine citrate was used as the model drug for its bitter taste, and a 3-point bend test was performed to assess the printability of filaments. The stiffness constant was calculated to represent the printability by fitting the breaking distances and stress data into Hooke's law. The formulations without Eudragit E PO (F6) and with Eudragit E PO (F7) filaments exhibited the desired hardness with a "k" value of 48.30 ± 3.52 and 45.47 ± 3.51 g/mm³ (n = 10), respectively, and were successfully printed. The donut-shaped tablets were 3D printed with 10, 50, and 100% infill densities. In vitro dissolution studies were performed in simulated salivary fluid (pH 6.8, artificial saliva) to evaluate the taste-masking efficiency of the printed donuts. In the first minute, the concentrations of caffeine citrate observed in the dissolution media from all the printed donuts were less than the bitter threshold of caffeine citrate (0.25 mg/mL). Formulation F7, which contained Eudragit E PO copolymer, demonstrated better taste-masking efficiency than formulation F6. Furthermore, both formulations F6 and F7 demonstrated immediate drug release profiles in gastric medium (10% infill, > 80% release within 1 h). Taste-masked caffeine citrate formulations were successfully developed with donut shapes, which will enhance appeal in pediatric populations and increase compliance and patient acceptance of the dosage form.

The preparation of lipid-based drug delivery system using melt extrusion

Melt extrusion of lipids is versatile with high applicability in the pharmaceutical industry. The formulations prepared can be easily customized depending on the requirements, and have the potential to open a window on personalized medicine.

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.

Developments in Taste-Masking Techniques for Traditional Chinese Medicines

A variety of pharmacologically active substances, including chemotherapeutic drugs and the substances from traditional Chinese medicine (TCM), always exhibit potent bioactivities after oral administration. However, their unpleasant taste (such as bitterness) and/or odor always decrease patient compliance and thus compromise their curative efficacies in clinical application. Therefore, the developments of taste-masking techniques are of great significance in improving their organoleptic properties. However, though a variety of taste-masking techniques have been successfully used to mask the unpalatable taste of chemotherapeutic drugs, their suitability for TCM substances is relatively limited. This is mainly due to the fact that the bitter ingredients existing in multicomponent TCM systems (i.e., effective fractions, single Chinese herbs, and compound preparations) are always unclear, and thus, there is lack of tailor-made taste-masking techniques to be utilized to conceal their unpleasant taste. The relevant studies are also relatively limited. As a whole, three types of taste-masking techniques are generally applied to TCM, including (i) functional masking via sweeteners, bitter blockers, and taste modifiers; (ii) physical masking via polymer film-coating or lipid barrier systems; and (iii) biochemical masking via intermolecular interaction, β-cyclodextrin inclusion, or ion-exchange resins. This review fully summarizes the results reported in this field with the purpose of providing an informative reference for relevant readers.

Spheronization of solid lipid extrudates: Elucidation of spheroid formation mechanism

To explain the rounding mechanism of extrudates by spheronization method, two main concepts are found in literature: one proposed by Rowe (1985) and one proposed by Baert et al. (1993). These concepts are based on wet extrusion-spheronization method using microcrystalline cellulose as mains excipient. However, there are no concepts for the spheronization mechanism of extrudates based on solid lipids as spheronization aid. Therefore, the aim of this study is to systematically investigate the mechanism of pellet formation of lipid based extrudates by lipid spheronization method. Different lipid based extrudate formulations were spheronized and particle size distribution and shape of the pellets, at each minute of the process, were characterized. Additionally, visual investigations of the morphological alterations were performed by optical and scanning electron microscopy. Two main material temperature phases were identified as presenting important influence on the pellet formation during the process: (1) a "brittle phase", where the extrudates are broken into smaller particles and (2) a "plastic phase", where the material starts to partially melt, allowing the particles to deform. By the same token, different morphological stages, from cylindrical rods to sphere-shaped passing through a dumbbell-shaped particle, were observed and showed to be highly dependent on temperature and process time. Moreover, a new particle shape, defined as "two-spheres", was recognized and a sequential material overlapping (covering) phenomenon was identified. This particular dislocation of material, from the edges to the central region of the particles (increasing their mean diameter), was recognized at longer process times and led to the formation of a smooth surface and the final spherical shape. At the end, a new concept of pellet formation from lipid extrudates is presented considering the observed changes in the morphology and particle size of the pellets during the spheronization process.

Early pediatric formulation development with new chemical entities: Opportunities of e-tongue besides human taste assessment

The palatability of a pediatric drug formulation is one of the key prerequisites for therapeutic success. Liquid formulations are often chosen for pediatric drug products, and they require special attention regarding their taste, as they have direct contact to the taste buds and a relatively long residence time in the oral cavity. For ethical reasons, the role of electronic tongues in the development of oral drug formulations with new chemical entities (NCEs) for pediatric use is growing, however, little is known about the strategies how this instrumental taste assessment can be performed. The present study illustrates two possibilities to combine in-vitro and in-vivo data for the characterization of the palatability of the new drug candidates CSE3104 and CSE3165. As a first step, the implementation and suitability of electronic tongue measurements has been demonstrated by comparison of in-vivo and in-vitro data. In alignment with the taste assessment results during a single-center, double-blinded, randomized, placebo-controlled, single ascending dose (SAD) study in healthy subjects, the bitter taste perception of CSE3104 was assessed with e-tongue measurements. Moreover, the sensor response pattern showed comparable results of the e-tongue measurements to the human taste study of CSE3165: With increasing concentration, the bitterness values were increased. In addition, the human taste pattern showed increasing values for sourness due to higher volumes of the citric acid buffer. Results of the hedonic descriptor "unpleasant" within the human taste assessments could be related to bitterness in the instrumental taste assessment. For the second step in electronic tongue guided formulation development two possibilities are depicted in the article focusing on the effect of different excipients on the formulation on the one hand and on the assessment and comparison of two drug formulations on the other hand. Based on these results, the low number of healthy volunteers for the taste assessment in a Phase 1 study led to a meaningful interpretation, by applying in addition the electronic tongue. Using this instrumental approach led to reproducible data versus the human taste assessment, without ethical concerns, and with a reduction in time and costs.