Masturbation matrix composition for simulating bitter taste after traditional Chinese medicine decoction, modified rheum officinale and coptis chinensis gargle masturbation and preparation method thereof

Abstract

The invention provides an application of combined use of xanthan gum, soya bean lecithin and a bitter agent in a bitter placebo matrix used in a traditional Chinese medicine decoction. The invention provides a placebo matrix composition capable of simulating the aftertaste of a traditional Chinese medicine decoction. The decoction comprises the following raw materials in percentage by weight: 0.03-0.04% of a bitterness agent, 0.05-0.2% of xanthan gum and 1.5-3% of soybean lecithin. The invention further provides the modified rheum officinale and coptis chinensis gargle placebo. Aiming at the defects that only instantaneous bitter taste can be generated by simply adding a bitterness agent and the bitter taste fades quickly in the prior art, the invention provides a method capable of actively regulating and remarkably prolonging the bitter taste sensing duration, so that the placebo can realistically reproduce a complete time-intensity curve of'bitter taste in mouth-lasting bitter taste after mouth 'of a traditional Chinese medicine decoction; therefore, the testee is prevented from being broken by bitterness lasting time difference. The method breaks through the limitation of traditional solution simulation, and aims to provide a new thought for preparation of traditional Chinese medicine placebo, further improve the sensory simulation level of the placebo and provide a method and reference for research of similar placebo.

Description

Technical Field

[0001] This invention relates to a placebo matrix composition that simulates the bitter taste of traditional Chinese medicine decoctions, as well as a placebo of rhubarb and coptis chinensis mouthwash and its preparation method. Background Technology

[0002] Currently, applications for registration of traditional Chinese medicine (TCM) are showing a continuous upward trend, and the number of Investigational New Drug (IND) applications is increasing year by year. In the TCM clinical evaluation system, conducting rigorous randomized, double-blind, placebo-controlled clinical trials is the "gold standard" for obtaining high-level evidence-based medicine. However, TCM preparations are complex in composition, and their oral dosage forms usually possess unique multi-dimensional sensory attributes such as shape, color, aroma, taste, and texture. This poses a significant challenge to the simulation preparation of Traditional Chinese Medicine Placebos (TCMPs). Traditional placebos often focus on simulating single attributes such as color or taste, making it difficult to systematically reproduce the overall sensory experience of TCM preparations, such as the duration of characteristic bitterness. At the same time, the degree of simulation in TCMPs directly affects the quality of clinical trials; insufficient simulation may lead to the risk of unblinding. TCM decoctions are complex in composition, and their taste (especially bitterness) not only comes from the instantaneous sensation upon ingestion but also often manifests as a persistent "aftertaste" after swallowing or gargling, which is determined by the slow release of various lipid-soluble, small-molecule bitter components. Existing technologies often focus on how to "mask" or "eliminate" unpleasant bitterness, such as through cyclodextrin inclusion, ion exchange resin adsorption, or the extensive use of sweeteners and flavoring agents. However, the preparation of placebos for traditional Chinese medicine is not only aimed at optimizing the taste of the medicinal liquid, but also at realistically simulating the bitterness of the real medicinal liquid.

[0003] The mechanism of "after-bitterness" in bitterness is quite complex, and the bitter substances differ among different drugs (Tan Chunhua, et al., Research progress on bitterness mechanism and novel bitterness inhibitors, Modern Food Science and Technology, 2025, Vol.41, No.7). Furthermore, the after-bitter substances also differ among different bitter drugs (Chen Yan, et al., Analysis of bitter metabolites after papaya fruit sap harvesting based on electronic tongue and metabolomics technology, *Southern Fruits of China*). Current placebo simulation techniques do not simulate the time sequence of bitterness. Conventional placebo preparations only focus on simulating color, appearance, and basic viscosity, or adding a small amount of bittering agent directly to the formulation. However, this only produces an initial "bitter taste," which quickly fades, failing to reproduce the complex time and intensity curve of "initial bitterness - prolonged after-bitterness" in real traditional Chinese medicine decoctions. This can easily lead to "unblinding" of clinical trials by subjects based on taste differences, rendering double-blind trials ineffective. While using thickeners can slightly delay taste diffusion, excessive amounts can result in an unrealistic sticky texture. How to achieve controlled and sustained release of bitter molecules without affecting the overall rheological properties of the drug solution is a key problem that urgently needs to be solved in this field.

[0004] Adding bittering agents to the base solution of placebo simulation can only produce "instantaneous bitterness." The bitterness is released quickly and fades quickly, failing to simulate the slow release and lingering bitterness caused by the complex components in real decoctions. Subjects are very likely to be blinded by the short duration of bitterness. Currently, most placebo bitterness simulations use the fat-soluble substance sucrose octaacetate, and the effect of adding thickeners alone on the sustained release of hydrophobic bitter molecules is also limited.

[0005] The modified rhubarb and coptis chinensis mouthwash originates from the rhubarb and coptis chinensis decoction in the *Shanghan Lun* (Treatise on Cold Damage). The original formula consists of rhubarb and coptis chinensis. The modified formula adds licorice and bletilla striata, possessing the effects of clearing heat and purging fire, astringing and promoting tissue regeneration. It is suitable for common oral diseases such as recurrent oral ulcers, gingivitis, and sore throat caused by stomach fire. To meet the needs of local oral treatment, this invention develops it into a mouthwash formulation that can directly act on the lesion, aiming to increase local drug concentration and prolong drug retention time. Analysis of the key sensory properties of this preparation reveals that it is a yellowish-brown suspension with poor light transmittance and a certain viscosity; the taste is predominantly bitter, with a noticeable lingering bitterness; the odor exhibits a typical earthy smell of rhubarb. Its turbid appearance and complex texture stem from the supramolecular ordered structure formed by the non-covalent interactions of multiple components in rhubarb and coptis chinensis, constituting a system with a complex phase. Unlike ordinary solutions, placebo simulation of this type of suspension and decoction with multiphase characteristics is more challenging. Therefore, objectively quantifying the sensory characteristics of formulations from multiple dimensions, analyzing the "time-effect-dose-effect" relationship of key sensory attributes, and constructing a corresponding simulation system are crucial for developing high-quality traditional Chinese medicine placebos. Summary of the Invention

[0006] This invention provides the application of xanthan gum, soybean lecithin, and bittering agents in a placebo matrix for the bitterness of traditional Chinese medicine decoctions.

[0007] This invention provides a placebo matrix composition that simulates the bitter taste of a traditional Chinese medicine decoction, wherein the decoction contains the following raw materials in weight percentages:

[0008] Bitterness agent 0.03%-0.04%, xanthan gum 0.05-0.2%, soybean lecithin 1.5-3%.

[0009] Preferably, the decoction contains the following ingredients in weight percentages:

[0010] Bittering agent 0.03%, xanthan gum 0.1%, soybean lecithin 2.5%.

[0011] The bittering agent mentioned is sucrose octaacetic acid ester.

[0012] The present invention also provides a placebo of rhubarb and coptis chinensis mouthwash, which contains a placebo matrix composition that simulates the bitter taste of traditional Chinese medicine decoction.

[0013] It contains 1% peppermint extract, an aromatic substance.

[0014] It also contains colorants lemon yellow, caramel color, and sunset yellow, with the following weight percentages: lemon yellow 0.0075%-0.01%, caramel color 0.0075%-0.01%, and sunset yellow 0.0075%-0.005%.

[0015] It also contains colorants lemon yellow, caramel color, and sunset yellow, with the following weight percentages: lemon yellow 0.01%, caramel color 0.1%, and sunset yellow 0.005%.

[0016] The present invention also provides a method for preparing the aforementioned flavored rhubarb and coptis chinensis mouthwash placebo, which includes the following steps:

[0017] a. Take pure water, add xanthan gum to 40% of the pure water, and stir evenly to form a network;

[0018] b. Add sucrose octaacetate to 60% pure water, dissolve it, and then slowly add soybean lecithin. Stir until evenly dispersed, and stir at 60°C for 15 minutes to encapsulate sucrose octaacetate in the hydrophobic core of soybean lecithin micelles. Then mix xanthan gum solution and soybean lecithin solution, and finally add pigment and flavor to obtain placebo solution.

[0019] The preparation method of the flavored rhubarb and coptis chinensis mouthwash is as follows:

[0020] Take 10g each of rhubarb, licorice and Bletilla striata, add 12 times the amount of water and soak for 30 minutes, decoct for 30 minutes and filter. Take 10g of Coptis chinensis and decoct for another 30 minutes. Filter through gauze. Combine the two filtrates, concentrate, filter, and prepare the solution.

[0021] For placebo simulation of traditional Chinese medicine decoctions with characteristic aftertaste and long bitterness duration, this invention primarily addresses the shortcomings of existing technologies that simply add bittering agents, which only produce instantaneous bitterness with rapid fading. It provides a method that can actively regulate and significantly prolong the duration of bitterness perception, enabling the placebo to realistically reproduce the complete time-intensity curve of traditional Chinese medicine decoctions—"bitter on the palate—with a long-lasting aftertaste," thus avoiding unblinding due to differences in bitterness duration among subjects. Furthermore, addressing the deficiency in existing placebos that often focus only on color, appearance, or basic viscosity while neglecting the simulation of taste timing, this invention provides a simulation scheme for simulating the bitterness timing of traditional Chinese medicine decoctions, thereby improving the overall simulation accuracy of the placebo.

[0022] Furthermore, taking the modified rhubarb and coptis chinensis mouthwash as an example, this invention comprehensively utilizes modern analytical techniques such as electronic tongue and rheometer to systematically characterize the color, taste, physicochemical properties (viscosity, turbidity, etc.), and rheological characteristics of the original herb, transforming subjective sensory impressions into objective and quantifiable data indicators. Based on this, addressing the technical challenge of the placebo's lack of nuanced bitterness, a placebo simulation study is conducted using "phase regulation" as the core strategy, ultimately producing a placebo that is highly similar to the original herb in shape, color, aroma, taste, and texture. This invention breaks through the limitations of traditional solution simulation, aiming to provide new ideas for the preparation of traditional Chinese medicine placebos, further improve their sensory simulation level, and provide methods and references for similar placebo research. Attached Figure Description

[0023] Figure 1 technical route

[0024] Figure 2 Comparison of placebo and original drug taste via electronic tongue

[0025] Figure 3 Comparison of bitter aftertaste between the 0.03% soybean egg group, the 0.03% xanthan gum group, and the 0.03% pure water group.

[0026] Figure 4 Human evaluation results (A: bitterness perception time; B: bitterness intensity at 15s; C: aftertaste bitterness intensity; D: bitterness duration; Note: *: P < 0.05, significant difference; **: P < 0.01, significant difference; ns: P > 0.05, no significant difference)

[0027] Figure 5 Rheological properties of mouthwash (A: Frequency scan results; B: Temperature scan results; C: Steady-state shear results)

[0028] Figure 6 Results of electronic tongue with mouthwash

[0029] Figure 7 Screening results of suspension systems (A: soluble starch (0.1%, 0.5%, 1%); B: soybean lecithin (0.1%, 0.5%, 1%); C: soybean protein powder (0.1%, 0.5%, 1%); D: microcrystalline cellulose (0.1%, 0.5%, 1%); E: corn starch (0.1%, 0.5%, 1%))

[0030] Figure 8 Gargle placebo original drug color screening results

[0031] Figure 9 PCA plot of electronic nose assay for mouthwash raw drug and placebo

[0032] Figure 10 Electronic tongue measurement radar image Detailed Implementation

[0033] Example 1: Placebo matrix composition of the present invention simulating the bitter taste after traditional Chinese medicine decoction.

[0034] This invention first uses a viscometer to measure the viscosity of xanthan gum at different concentrations, selects the optimal viscosity for matching the traditional Chinese medicine liquid, then uses ultraviolet light or a turbidimeter to measure the turbidity of soybean lecithin at different concentrations, selects the optimal formulation, and finally determines the optimal liquid matrix for the placebo. Then, it screens the taste formulation. This invention mainly uses sucrose octaacetate as the main bittering agent. The optimal placebo taste formulation is determined by measuring the bitterness intensity using an electronic tongue combined with human evaluation. Human evaluation is then used to screen the duration of bitterness in the pure water + bittering agent group, the pure water + xanthan gum + bittering agent group, and the pure water + xanthan gum + soybean lecithin + bittering agent group.

[0035] Electronic tongue method: 30 mM potassium chloride + 0.3 mM tartaric acid was used as the reference solution; 100 mM hydrochloric acid + 30% ethanol (v / v) was used as the negative electrode cleaning solution; and 10 mM potassium hydroxide + 100 mM potassium chloride + 30% ethanol (v / v) was used as the positive electrode cleaning solution. Samples were centrifuged, filtered, and then tested. The sensor was first cleaned in the cleaning solution for 90 s, then in the reference solution for 120 s, and then in another reference solution for 120 s. The sensor was zeroed at equilibrium for 30 s. Testing: The test time was 30 s, and the initial taste value was output. Afterward, the sensor was cleaned in the reference solution for 3 s, and then the aftertaste was tested in a new reference solution for 30 s. The five taste sensors (C00, AE1, CA0, CTO, AAE) and the bitter taste sensors (ANO, BTO) were tested 4 times. The first cycle was discarded, and the average of the last three cycles was taken as the test result. The sweet taste sensor (GL1) was tested 5 times. The first and last cycles were discarded, and the average of the middle three cycles was taken as the test result.

[0036] Manual evaluation method: At least 10 volunteers were recruited after screening to evaluate the bitterness of the raw drug. Each volunteer, under standardized guidance, held 10 mL of the constant-temperature raw drug solution in their mouth for 30 seconds before spitting it out, allowing the tongue and oral cavity to fully experience the taste. The volunteers scored the bitterness based on facial micro-expressions and taste intensity. The scoring items included the perceived intensity 15 seconds after ingestion, the perceived intensity 15–60 seconds after spitting out the solution, and the duration of the bitter aftertaste. Bitterness intensity was scored from 0 to 10, with 0–2 indicating almost no bitterness, 2–4 indicating mild bitterness, 4–6 indicating noticeable bitterness, 6–8 indicating strong bitterness, and 8–10 indicating severe bitterness. Data were recorded and analyzed.

[0037] The electronic tongue test results showed that a 0.03% concentration of bittering agent was similar to that of the original Chinese medicine extract. Figure 4The results showed that, compared with the original drug, the liquid containing pure water + xanthan gum + soy lecithin + bittering agent had a longer bitterness duration than the liquid containing only bittering agent or only a single thickener, with statistically significant differences (P < 0.01). Its bitter aftertaste was also stronger than the pure water group and the group containing only xanthan gum, with statistically significant differences (P < 0.05). Meanwhile, the formulation of 0.03% sucrose octaacetate + 0.1% xanthan gum + 2.5% soy lecithin did not show significant differences in bitterness duration and aftertaste intensity compared with the original drug (P > 0.05), but there was a slight difference in bitterness perception time. This may be because the addition of xanthan gum and soy lecithin delayed the contact time between the bittering agent and bitter taste receptors. (Results are shown in Table 1.) Figures 1-4 ).

[0038] Table 1. Results of Human Evaluation

[0039]

[0040] Compared with existing technologies, this invention, through the combination and synergistic application of xanthan gum and soybean lecithin, for the first time shifts the focus of placebo taste simulation from simulating the intensity of a single bitter taste to simulating the layers of bitterness. The xanthan gum network provides a stable dispersion framework for lecithin micelles, while the lecithin micelles act as a reservoir of bitter molecules embedded in the network. Together, they constitute a dynamic controlled-release system that can actively and significantly prolong the perceived duration of bitterness. Experimental data show that the placebo prepared using this invention has a longer bitterness duration than control samples using only conventional bitterness-adding methods or single colloids. This allows for a highly realistic reproduction of the unique after-bitterness of traditional Chinese medicine decoctions, mitigating the risk of "unblinding" in clinical trials due to taste differences. The placebo prepared by this invention is similar to the original drug in the temporal characteristics of bitterness, ensuring the rigor and reliability of results in randomized double-blind controlled clinical trials, and providing crucial technical support for obtaining high-level evidence-based medicine.

[0041] This invention overcomes the limitations of single-material functionality. At the same time, the preparation method has clear steps and well-defined parameters, does not rely on complex equipment, and uses commercially available food-grade or pharmaceutical-grade excipients. The cost is controllable, the safety is high, and it is easy to carry out standardized production and large-scale preparation, thus having good prospects for industrial transformation.

[0042] Furthermore, the main reason for choosing xanthan gum as the colloid in this invention is that most traditional Chinese medicine liquids exhibit shear-thinning properties, and xanthan gum also possesses this property. Xanthan gum can be replaced by other pseudoplastic colloids with shear-thinning properties; sucrose octaacetic acid esters can be replaced by micelles formed by other emulsifiers or surfactants (such as Tween 80, monoglycerides).

[0043] Example 2: Preparation of a placebo of rhubarb and coptis chinensis mouthwash

[0044] 1. Instruments and reagents

[0045] 1.1 Instruments

[0046] Magnetic stirrer (ETS-2A, Changzhou Yuexin Instrument Manufacturing Co., Ltd.); Triple quadrupole gas chromatography-mass spectrometry (GCMS-TQ8050NX, Shimadzu Corporation, Japan); PAL SPME Arrow solid-phase microextraction injector (1.5 mm*120 μm*20 mm, PN: ARR15-DVB / C-WR-120 / 20CT, CTC Corporation, Switzerland); Electronic tongue (Model: SA402B, Insent Corporation, Japan); Rotational viscometer (NTV-P2LV, Shanghai Nirun Intelligent Technology Co., Ltd.); Ultraviolet spectrophotometer (UV-6100, Shanghai Yuanxi Instrument Co., Ltd.); Intelligent rheology analyzer (DHR-2, Waters Corporation, USA); Induction cooker; Analytical balance (BT125D, Sartorius GmbH, Germany).

[0047] 1.2 Reagents

[0048] Lemon yellow; caramel color; sunset yellow; sucrose octaacetate; soy lecithin; soy protein powder; microcrystalline cellulose; sodium carboxymethyl cellulose; soluble starch; carrageenan; xanthan gum; peppermint flavor.

[0049] 2. Experimental Methods

[0050] 2.1 Preparation of the test sample for a modified rhubarb and coptis chinensis purgative mouthwash

[0051] This formula consists of rhubarb, coptis, licorice, and bletilla. Take 10g each of rhubarb, licorice, and bletilla, add 12 times the amount of water and soak for 30 minutes. After decocting for 30 minutes, filter. Take 10g of coptis and decoct for another 30 minutes. Filter through gauze. Combine the two filtrates, concentrate, filter, and dilute to obtain the final product.

[0052] 2.2 Color Characterization of Raw Material for Modified Rhubarb and Coptis Chinensis Mouthwash

[0053] Because mouthwash itself is cloudy and has strong light scattering properties, it conflicts with the measurement principle of colorimeters, which rely on specular reflection. Therefore, colorimeters cannot accurately determine the color of the mouthwash. This invention uses a camera (SONY, ILCE-A7M2) under a fixed light source to photograph the samples, obtaining RAW format images. Three images are taken for each sample. A white balance corrected image is obtained through grayscale correction. After processing with Photoshop 2025 software, three points are randomly selected using a 5x5 eyedropper tool, and the L*, a*, and b* values ​​are measured. The mean ± SD of L*, a*, and b* are calculated.

[0054] 2.3 Physicochemical Properties Characterization of Raw Material for Modified Rhubarb and Coptis Chinensis Mouthwash

[0055] 2.3.1 Viscosity Measurement

[0056] Viscosity is a subjective feeling experienced by patients when tasting medication. Appropriate initial viscosity determines the oral adhesion of the medication, including its residence time on the oral mucosa and its local action time. In terms of taste, it affects the contact intensity between the medication and taste buds, influencing the diffusion and release of bitter substances. Viscosity measurement can objectify and quantify this subjective feeling. This invention uses a rotational viscometer. The sample is poured into a sample cup and placed in a constant temperature water bath at approximately 25°C. A rotor of size 0 is selected, and the rotational speed is fixed at 60 r·min⁻¹. After the data stabilizes, the viscosity value (MPa·s) and torque percentage (%) are recorded. Measurements are taken three times.

[0057] 2.3.2 Turbidity Measurement

[0058] The turbid, opaque appearance of the original drug solution is its most obvious physical characteristic and the first intuitive feeling that placebo simulation needs to reproduce. Turbidity is also closely related to the concentration, particle size, and distribution of the dispersed phase particles. It can also serve as a preliminary screening indicator when screening placebo excipients, allowing for direct observation of whether the drug solution has aggregated, settled, or flocculated. This invention uses an ultraviolet spectrophotometer with a wavelength of 700 nm. After blank calibration, the sample solution is injected for measurement, and the absorbance is recorded. Each sample should be measured at least three times, and the average value and standard deviation are taken.

[0059] 2.3.3 Rheological property determination

[0060] Rheological properties determine the dynamic sensory experience of a medicinal solution throughout its entire process, from pouring and rinsing to its coverage and retention on the oral mucosa. This is reflected in the thickness, smoothness, and enveloping sensation of the solution upon entry, the resistance felt during rinsing, the film-forming sensation after spitting, and the release pattern of flavor compounds. This invention uses an intelligent rheological analyzer to determine the viscoelasticity, yield stress, thixotropy, and other properties of the samples.

[0061] This invention employs a coaxial cylindrical measuring system. The sample is added to the measuring cup and allowed to stand for 5 minutes to allow the solution temperature to equalize before testing. Before the oscillation test, the linear viscoelastic region (LVR) of the sample is determined by strain scanning, and 0.1% is selected as the fixed strain for the subsequent oscillation test.

[0062] Temperature scanning method: Temperature scanning was performed at a fixed oscillation frequency of 1.0 Hz and a strain of 0.1%, with a temperature range of 20–50 °C and a heating rate of 1 °C / min. The changes in storage modulus (G') and loss modulus (G") with temperature were measured. Oil was applied to the sample surface during the test to reduce the influence of moisture evaporation on the measurement results.

[0063] Frequency scanning method: Frequency scanning was performed at 25℃ with a fixed strain of 0.1%, and the angular frequency range was 0.628~628 rad / s. The changes of sample G' and G'' with angular frequency were measured.

[0064] Steady-state shear scanning method: Steady-state shear scanning was performed at 25℃ with shear rates ranging from 0.1 to 300 s⁻¹, varying logarithmically, to determine the relationship between viscosity and shear rate. Before the shear scan, a pre-shear at a shear rate of 10 s⁻¹ for 30 s was performed to eliminate sample shear history and ensure system homogeneity.

[0065] 2.4 Taste Characteristics of Raw Materials in Modified Rhubarb and Coptis Chinensis Mouthwash

[0066] 2.4.1 Electronic tongue measurement

[0067] Taste hierarchy was characterized using an electronic tongue. A 30 mM potassium chloride + 0.3 mM tartaric acid solution was used as the reference solution. A 100 mM hydrochloric acid + 30% ethanol solution was used as the negative electrode cleaning solution, and a 10 mM potassium hydroxide + 100 mM potassium chloride + 30% ethanol solution was used as the positive electrode cleaning solution. The sensor was first cleaned in the cleaning solution for 90 s, then in the reference solution for 120 s, and then in another reference solution for another 120 s. The sensor was zeroed at its equilibrium position for 30 s. After centrifugation, the sample was tested for 30 s, and the initial taste value was output. Afterward, the sensor was cleaned in the reference solution for 3 s, and then inserted into a new reference solution to test the aftertaste for 30 s. The five taste sensors (C00, AE1, CA0, CTO, AAE) and the bitter taste sensors (ANO, BTO) were tested four times. The first cycle was discarded, and the average of the last three cycles was taken as the test result. The sweet taste sensor (GL1) was tested five times. The first and last cycles were discarded, and the average of the middle three cycles was taken as the test result.

[0068] 2.4.2 Artificial sensory evaluation

[0069] At least 10 volunteers were selected and recruited to evaluate the bitterness of the original medicine. Under standard guidance, each volunteer held 10 mL of the original medicine solution at a constant temperature in their mouth and gargled for 30 seconds before spitting it out, allowing their tongue and oral cavity to fully experience the taste of the medicine. The volunteers were scored based on changes in facial micro-expressions and the intensity of the taste. The scoring items included the intensity of the taste perceived when the medicine entered the mouth, the intensity of the taste perceived at 15 seconds, the intensity of the taste perceived after spitting out the medicine (15-60 seconds), the initial point of bitterness perception, and the duration of the aftertaste.

[0070] The bitterness intensity ranged from 0 to 10 points, with 0-2 points indicating almost no bitterness, 2-4 points indicating slight bitterness, 4-6 points indicating noticeable bitterness, 6-8 points indicating strong bitterness, and 8-10 points indicating severe bitterness. The data were recorded and then analyzed.

[0071] 3. Research Results

[0072] 3.1 Color Characterization Results of Modified Rhubarb and Coptis Chinensis Mouthwash

[0073] This invention employs the L*a*b uniform color space system. The experimentally measured L*, a*, and b* values ​​represent the three dimensions of the color measurement system. The "L*" value represents the object's lightness; "a*" and "b*" represent different hue directions: +a* represents the red direction, -a* represents the green direction, +b* represents the yellow direction, and -b* represents the blue direction. ΔE* represents the total color difference of the samples. Using the mean value as a benchmark, ΔE is calculated between different samples. ΔE* < 3.0 indicates a high similarity between the sample and the original drug; ΔE* > 5.0 indicates significant differences between the samples. The relationship between ΔE* and L*, a*, and b* is given by the formula ΔE* = √(ΔL*). 2 + (Δa*) 2 +(Δb*) 2 ]

[0074] 3.2 Physicochemical Properties Characterization Results of Modified Rhubarb and Coptis Chinensis Mouthwash

[0075] 3.2.1 Viscosity

[0076] The smooth, viscous texture of the original drug primarily originates from Bletilla striata polysaccharides. Its viscosity characteristics not only affect the physical stability of the formulation but also the core sensory experience after ingestion, including the spread of the drug in the mouth and the lingering sensation. This influences patients' subjective experience and adherence. If the placebo deviates from this crucial parameter, subjects can subjectively identify the difference between the placebo and the actual drug through variations in smoothness and viscosity, leading to the failure of the double-blind design and introducing immeasurable subjective bias. In this invention, the viscosity of the original drug was measured to be 10.56 ± 0.02 mPa·s using a rotational viscometer.

[0077] 3.2.2 Turbidity

[0078] The texture of the medicinal solution is the second most noticeable characteristic. The medicinal solution prepared in this invention differs from ordinary solutions, exhibiting multiple phases and appearing turbid. Subjects can easily detect this abnormality visually. Therefore, this invention selects 700nm as the turbidity measurement wavelength. This band lies in the red visible light region, effectively avoiding the characteristic absorption peaks of most organic pigments in traditional Chinese medicine (such as flavonoids and anthraquinones). Water also does not absorb light at this wavelength, ensuring that the signal changes measured by the instrument mainly originate from the scattering and blocking of light by suspended particles in the sample, rather than interference from the solution's color itself. Therefore, the absorbance value obtained under these conditions can serve as a stable and reliable indicator of relative turbidity. In this invention, the original medicine was diluted 10 times, and the absorbance measured at 660nm was 0.465±0.002.

[0079] 3.2.5 Rheological characteristics

[0080] Dynamic temperature scanning is to study changes such as material softening, melting, solidification, crystallization, decomposition, and chemical reactions by monitoring the changes of storage modulus G' and loss modulus G'' with temperature under constant small amplitude and frequency. Among them, the storage modulus G' represents the ability of the material to store elastic deformation energy and reflects the rigidity of the material, and the loss modulus G'' represents the ability of the material to dissipate energy and reflects the viscous or damping characteristics of the material. Dynamic frequency scanning is to monitor the changes of G' and G'' with frequency under constant temperature and small amplitude conditions. The steady-state shear mode is to apply strain or stress using continuous rotation to obtain the torque at a constant shear rate, which is used to study fluid fluidity, and information such as flow curve, viscosity curve, viscosity-temperature curve, yield stress, and thixotropy can be obtained.

[0081] During the steady-state scanning process, the sample exhibits solid characteristics (G' > G'') at high frequencies and fluid characteristics (G' < G'') at low frequencies. As can be seen from Figure 5 A, G' > G'' within the full frequency range, indicating that the sample is dominated by elasticity throughout the test frequency range, that is, a gel or solid film. At the same time, both G' and G'' increase slightly with frequency, but the change is not significant, indicating that the sample has low frequency sensitivity and a stable network structure. It shows that the mouthwash is a weakly flowing gel sample when containing water. As can be seen from Figure 5 B, it maintains solid elastic behavior within the temperature range of 15–35 °C, and as the temperature increases, the sample gradually softens but no phase change occurs. Being dominated by elasticity (G' > G''), it indicates that its structural stability is good. It shows that the mouthwash is a tough solid film after drying. As can be seen from Figure 5 C, within the entire shear rate range of 0.1~270 s -1 , the viscosity monotonically decreases from 0.08 Pa·s to 0.005 Pa·s, a decrease of 16 times, which is a typical shear thinning. And in the low shear region (<1 s -1 ), the viscosity drops fastest, indicating that the polysaccharide network is quickly disassembled. In the high shear region (>100 s -1 ), the viscosity tends to a plateau of 0.004 Pa·s, indicating that the network is almost completely oriented and there is no obvious thinning.

[0082] 3.4 Taste characterization results of the modified Rhubarb and Coptis Decoction for purging Heart-Fire mouthwash

[0083] Traditional Chinese medicine preparations have complex flavors, and characterizing their bitterness levels is crucial. This invention combines volunteer sensory evaluation with an electronic tongue to characterize the bitterness levels of drugs. The electronic tongue can objectively, stably, and reproducibly screen samples quickly and quantify the basic bitterness intensity. It can detect the aftertaste or astringency of bitterness through specific sensors, but it is difficult to convert time-related information such as duration. Volunteer sensory evaluation can finely describe the dynamic levels of bitterness, such as the onset speed, peak intensity, duration, and aftertaste characteristics, but it also has limitations such as individual differences, unsuitability for screening large numbers of samples, and certain tolerance. Combining the two evaluation methods allows for a better assessment of the overall taste of the drug.

[0084] 3.5.1 Volunteer Evaluation

[0085] According to the volunteer evaluation results in Table 2, the mouthwash was extremely bitter upon entry, the bitterness intensity remained unchanged during rinsing, and a bitter taste remained in the mouth after spitting. The bitterness lasted for more than 3 minutes. Therefore, the placebo should focus on the characteristic of persistent bitterness after rinsing and spitting in simulating the bitterness intensity, in order to prevent patients from breaking the blindness and affecting the quality of the clinical trial.

[0086] Table 2. Sensory evaluation results of volunteers

[0087]

[0088] 3.5.2 Results of Electronic Tongue

[0089] The electronic tongue used in this invention uses KCl and tartaric acid as reference solutions to determine the taste value, with the taste-free point as the reference. The taste-free point for bitterness is 0, for sourness it is -13, and for saltiness it is -6. Based on this, when the taste value of a sample is lower than the taste-free point, it indicates that the sample has no taste, and vice versa. The electronic tongue results show that the bitterness intensity is 5.26, significantly higher than the taste-free point (0); the bitter aftertaste intensity is 4.47, higher than the taste-free point (0); the sourness intensity is -19.37, lower than the taste-free point (-13); the saltiness intensity is -7.13, lower than the taste-free point (-6); and the astringent and umami intensities are 0.77 and 0.46, respectively, both slightly higher than the taste-free point (0). In summary, the mouthwash raw material has a significant bitterness and bitter aftertaste, and low astringent and umami intensities (see...). Figure 6 ).

[0090] 4. Placebo formulation screening and preparation of modified rhubarb and coptis chinensis purgative mouthwash

[0091] 4.1 Matrix Screening

[0092] The modified rhubarb and coptis chinensis mouthwash is turbid. Previous studies have determined that the mouthwash is mainly composed of colloidal and suspension components. Therefore, this experiment mainly screens excipients that can form colloidal and suspension components, with viscosity and turbidity as the main screening indicators.

[0093] 4.1.1 Thickener Screening

[0094] According to the "Technical Guidelines for the Preparation and Research of Drugs for Clinical Trials of New Traditional Chinese Medicines (Trial Implementation)," placebo mimicry excipients should not cause harm to the human body and should meet pharmaceutical standards. If no pharmaceutical standards exist, they should at least meet food additive standards. Our research group previously screened excipients such as xanthan gum, gum arabic, pectin, carrageenan, and sodium carboxymethyl cellulose (CMC-Na). These excipients are all natural or semi-natural polysaccharide polymers, all of which are food additives permitted under national food safety standards and have been widely used in various processed foods for a long time. Their safety has been fully verified, and they have no known pharmacological effects or active ingredients. The results show that xanthan gum and CMC-Na can provide higher viscosity at the same concentration and can be used as colloidal matrices for mimicry drug solutions. However, although CMC-Na exhibits a higher apparent viscosity under low shear measurements, its rheological properties tend to provide a more uniform, high-viscosity texture. However, based on the rheological characterization results of the original drug, the solution exhibits significant shear-thinning behavior, meaning it flows well during pouring and oral administration, and remains suspended after standing. The pseudoplasticity and thixotropy of xanthan gum allow it to more accurately simulate this rheological characteristic at lower dosages. Therefore, this invention tentatively selects 0.2% xanthan gum as the colloidal matrix.

[0095] Table 3 Screening results for xanthan gum dosage

[0096]

[0097] 4.1.2 Screening of Hybrid Suspension Systems

[0098] The mouthwash appears cloudy and opaque; therefore, this invention screens five excipients to increase its turbidity. (See Table 4...) Figure 7 The results showed that the excipients that could produce a suspension state were soluble starch, corn starch, and soy lecithin. After measuring the turbidity of the three excipients at different dosages at 660 nm, it was found that the turbidity of soluble starch did not change much with the increase of dosage and could not reach the turbidity of the original drug. Corn starch had high turbidity, but the viscosity of the liquid also increased with the increase of dosage. It was easy to gelatinize during heating and easy to solidify after cooling. Soy lecithin and microcrystalline cellulose had high turbidity, but their particle size was large. After the addition of pigment, the difference in fineness between them and the original drug could be clearly observed with the naked eye, and they also had a lot of sedimentation. Soy lecithin was homogeneous and stable throughout the process and could produce turbidity matching that of the original drug. Therefore, this invention selected soy lecithin as a placebo matrix to produce turbidity.

[0099] Table 4 Screening results of excipients for dispersion systems

[0100]

[0101] Table 5. Turbidity Screening Results

[0102]

[0103] 4.1.2 Multi-factor ratio analysis

[0104] During the screening of turbidity agents, it was found that increasing the amount of soybean lecithin would also change the viscosity of the liquid. Therefore, in order to better simulate the matrix of the original drug, this invention conducted an orthogonal experiment on xanthan gum and soybean lecithin to select a better formulation. The results in Table 5 show that 0.1% xanthan gum and 2.5% soybean lecithin match the viscosity and turbidity of the original drug. Therefore, this invention adjusts the formulation based on this to obtain the optimal formulation.

[0105] Table 6. Placebo matrix screening results

[0106]

[0107] 3.2 Screening of Bitter Agent Dosage

[0108] TCMP commonly uses bittering agents to simulate the bitterness of test drugs. This invention examines the dosage of bittering agents based on the basic formulation determined after matrix screening, aiming to achieve a bitterness intensity similar to the original drug. Currently, excipients that can be used to simulate the bitterness of a placebo include food additives such as bitter melon extract, limonin, and sucrose octaacetate. However, studies have shown that bitter melon extract and limonin both possess anti-inflammatory and antibacterial pharmacological activities. To eliminate interference from pharmacological activities, this invention selects sucrose octaacetate as a bittering agent, examines the dosage, and uses volunteers to evaluate the similarity of bitterness intensity between the placebo and the original drug. The similarity score is out of 10; the higher the similarity, the more similar the bitterness intensity of the placebo is to the original drug. According to the results of the manual evaluation in Table 6, the bitterness of 0.03% sucrose octaacetate is similar to that of the original drug. Therefore, this study selects 0.03% sucrose octaacetate as the placebo bittering agent.

[0109] Table 7 Screening results for bittering agent dosage

[0110]

[0111] 3.3 Screening of Odor Substance Dosage

[0112] The mouthwash used in this invention is a new drug for treating oral diseases. In order to increase patient compliance, peppermint flavoring was added to the original drug. Therefore, peppermint flavoring was also added to the placebo. During the addition process, we found that the flavoring could effectively mask the slight fishy smell of soy lecithin. Therefore, this invention selected a 0.1% concentration of peppermint flavoring.

[0113] 3.4 Screening of colorant dosage

[0114] The original solution of this invention is yellowish-brown with a hint of orange. Based on previous experiments, this invention uses lemon yellow, sunset yellow, and caramel coloring to simulate the color of the mouthwash, examining the amount and ratio of these colors used. (See Table 8.) Figure 8 The results show that Formula 1 has the best color formula and is highly similar to the original solution.

[0115] Table 8. Placebo Color Screening Results

[0116]

[0117] Table 9 Placebo Colorant Formulation Table

[0118]

[0119] 3.5 Final preparation method of placebo

[0120] Take 100ml of pure water, add 100mg of xanthan gum to 40ml of pure water and stir until it forms a network. Add 30mg of sucrose octaacetate to 60ml of pure water and dissolve it. Slowly add 2.5g of soy lecithin and stir until it is evenly dispersed. Stir at 60℃ for 15min to encapsulate the bittering agent in the hydrophobic core of the micelles. Then mix the xanthan gum solution and the soy lecithin solution. Finally, add pigment and flavor to obtain the placebo solution.

[0121] 4. Evaluation of the effects of placebo simulation

[0122] 4.1 Subjective Evaluation

[0123] The placebo needs to be basically consistent with the traditional Chinese medicine preparation in the clinical trial in terms of appearance, color, smell, taste, packaging, dosage, and usage. However, there is currently no standardized evaluation method for placebo quality, and domestic research methods mostly use manual scoring as a subjective evaluation method. Fifteen volunteers were recruited, and the investigational drug was designated as drug A, and the placebo as drug B. The evaluators were blinded, and one of drugs A or B, and one of the investigational drug were randomly distributed, with 8 samples of the investigational drug and 7 samples of the placebo. Volunteers were asked to rate the similarity between the placebo and the investigational drug in four aspects: appearance, color, taste, smell, and odor. The scoring used the internationally recognized Likert scale, with scores from 0 to 10. 0 points represented completely different from the investigational drug, 2.5 points for significant difference, 5.0 points for uncertainty, 7.5 points for similarity, and 10.0 points for identical. Scores in between were assigned at the discretion of the evaluator. Statistical analysis of the results was performed using SPSS 13.0 software for analysis of variance (ANOVA). The analysis of variance results showed that there were no statistically significant differences between the experimental drug A and the placebo B in the four sensory evaluation dimensions of appearance, color, taste, and odor. Table 10 shows that the analysis of variance results showed that there were no statistically significant differences between the experimental drug and the placebo in the four sensory evaluation dimensions of appearance, color, taste, and odor. From the overall average value, the mean scores of group A in each dimension were slightly higher than those of group B, but the similarity score of group B was higher, so it can be considered that its sensory quality was basically consistent with that of group A.

[0124] Table 10 Comparative Evaluation Results

[0125]

[0126] 4.2 Objective Evaluation

[0127] 4.2.1 Electronic nose

[0128] This invention uses an electronic nose for odor similarity evaluation. The electronic nose has 10 electrodes (W1C, W5S, W3C, W6S, W5C, W1S, W1W, W2S, W2W, W3S). The sampling time is 1 s / group, the sensor self-cleaning time is 150 s, the injection flow rate is 1 mL / min, and the analysis sampling time is 300 s. The test solution is taken, placed in a sample cup, sealed, and allowed to stand for 30 min before measurement. Based on the raw response data collected by the sensor, PCA analysis is performed using Origin software. The distance between samples on the PCA graph is used to determine the odor difference between samples; the smaller the distance, the higher the similarity of the samples with the electronic nose.

[0129] Depend on Figure 9PCA results showed that PC1 and PC2 contributed 97.1% and 2.6% respectively, with a cumulative contribution of 98.7%, basically covering most of the original information of the sample. The placebo and the original drug were close to each other on PC1, indicating that the placebo and the original drug were highly similar. The flavoring could mask the fishy smell produced by soy lecithin, and the results were consistent with the results of manual evaluation.

[0130] 4.2.2 Electronic tongue

[0131] This invention uses an electronic tongue for taste similarity evaluation. After centrifugation and filtration, samples are tested for 30 seconds, outputting the initial taste value. Following this, the sample is washed with a reference solution for 3 seconds, and the sensor is then immersed in a new reference solution for a 30-second aftertaste test. The five taste sensors (C00, AE1, CA0, CTO, AAE) and the bitter taste sensors (ANO, BTO) are tested four times, with the first cycle discarded and the average of the last three cycles taken as the result. The sweet taste sensor (GL1) is tested five times, with the first and last cycles discarded and the average of the middle three cycles taken as the result. Radar response data from the electronic tongue sensors show that the placebo and the original mouthwash have similar response intensities on the sensor, indicating good similarity (see...). Figure 10 ).

[0132] 3 Discussion

[0133] Unlike Western medicine, traditional Chinese medicine (TCM) preparations have complex sensory characteristics. Their color is a complex of multiple pigments, and their aroma is presented by the special volatile components of TCM. It is difficult to find flavorings on the market that match the special aroma of TCM. At the same time, the taste of TCM is complex and is not a single constant taste signal, but rather a temporal change from the initial taste to the aftertaste. Traditional placebo preparation technology only simulates the instantaneous taste by directly adding flavoring agents, which causes the taste to quickly disappear after swallowing. Unlike the long-lasting aftertaste of real TCM preparations, subjects may identify their group by the aftertaste in their mouth, which can lead to the failure of blinding and bias in the test results.

[0134] To enhance the placebo simulation, some studies employ the "low-dose original drug method." While this method improves the sensory simulation effect of the placebo, it cannot completely eliminate pharmacological activity. The regulatory framework and technical standards for placebos are also currently incomplete. Although the "General Principles of Clinical Research on New Traditional Chinese Medicines" explicitly requires that placebos be similar to the investigational drug in terms of color, odor, taste, shape, and texture, this requirement is only a general statement and lacks supporting technical guidelines and acceptable thresholds for the similarity between placebos and investigational drugs. Currently, the evaluation of placebo simulation effects mainly relies on manual judgment, using independent or comparative evaluation methods to score the similarity between the placebo's shape, color, odor, and taste and the original drug. However, manual evaluation is highly individualized and difficult to standardize. Therefore, improving the simulation level of traditional Chinese medicine placebos and perfecting scientific similarity evaluation standards and related legal regulations remain critical issues that urgently need to be addressed.

Claims

1. Application of xanthan gum, soybean lecithin, and bittering agents in a placebo matrix for the bitterness of traditional Chinese medicine decoctions.

2. A placebo matrix composition that simulates the bitter taste of traditional Chinese medicine decoctions, characterized in that: The decoction contains the following ingredients in weight percentage: Bitterness agent 0.03%-0.04%, xanthan gum 0.05-0.2%, soybean lecithin 1.5-3%.

3. The placebo matrix composition for simulating the bitter taste of traditional Chinese medicine decoction according to claim 2, characterized in that: The decoction contains the following ingredients in weight percentage: Bittering agent 0.03%, xanthan gum 0.1%, soybean lecithin 2.5%.

4. The placebo matrix composition for simulating the bitter taste of traditional Chinese medicine decoction according to claim 2 or 3, characterized in that: The bittering agent mentioned is sucrose octaacetic acid ester.

5. A placebo-like mouthwash with added rhubarb and coptis, characterized in that: It contains a placebo matrix composition that simulates the bitter taste of traditional Chinese medicine decoction as described in any one of claims 2-4.

6. The placebo mouthwash with added rhubarb and coptis according to claim 5, characterized in that: It contains 1% peppermint extract, an aromatic substance.

7. The placebo mouthwash with added rhubarb and coptis according to claim 6, characterized in that: It also contains colorants lemon yellow, caramel color, and sunset yellow, with the following weight percentages: lemon yellow 0.0075%-0.01%, caramel color 0.0075%-0.01%, and sunset yellow 0.0075%-0.005%.

8. The placebo mouthwash with added rhubarb and coptis according to claim 7, characterized in that: It also contains colorants lemon yellow, caramel color, and sunset yellow, with the following weight percentages: lemon yellow 0.01%, caramel color 0.1%, and sunset yellow 0.005%.

9. A method for preparing a placebo of rhubarb and coptis chinensis mouthwash according to any one of claims 5-8, characterized in that: It includes the following steps: a. Take pure water, add xanthan gum to 40% of the pure water, and stir evenly to form a network; b. Add sucrose octaacetate to 60% pure water, dissolve it, and then slowly add soybean lecithin. Stir until evenly dispersed, and stir at 60°C for 15 minutes to encapsulate sucrose octaacetate in the hydrophobic core of soybean lecithin micelles. Then mix xanthan gum solution and soybean lecithin solution, and finally add pigment and flavor to obtain placebo solution.

10. The placebo mouthwash with added rhubarb and coptis according to any one of claims 5-8, or the method for preparing the placebo mouthwash with added rhubarb and coptis according to claim 9, characterized in that: The preparation method of the flavored rhubarb and coptis chinensis mouthwash is as follows: Take 10g each of rhubarb, licorice and Bletilla striata, add 12 times the amount of water and soak for 30 minutes, decoct for 30 minutes and filter. Take 10g of Coptis chinensis and decoct for another 30 minutes. Filter through gauze. Combine the two filtrates, concentrate, filter, and prepare the solution.

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