A simulated fasting gastric juice in humans and its preparation method

Abstract

This invention discloses a simulated fasting gastric juice and its preparation method, belonging to the field of in vitro dissolution testing technology for pharmaceutical preparations. The invention aims to address the problem that existing simulated gastric juice differs significantly from real fasting gastric juice in terms of surface tension, osmotic pressure, and buffering capacity, leading to inaccurate in vitro assessments of drug dissolution behavior and affecting the scientific validity and reliability of in vitro drug dissolution experiments. The human simulated fasting gastric juice comprises bovine serum albumin 2–30 mg / mL, glycocholic acid or glycocholate 0–7.517E-0.5 mol / L, glycochenodeoxycholic acid or glycochenodeoxycholate 0–7.421E-0.5 mol / L, taurocholic acid or taurocholate 0–8.369E-0.4 mol / L, taurochenodeoxycholic acid or taurochenodeoxycholate 0–9.005E-0.4 mol / L, calcium chloride 0.025–0.138 g / L, potassium chloride 0.478–1.12 g / L, magnesium chloride 0.015–0.063 g / L, sodium chloride 2.05–5.26 g / L, sodium dihydrogen phosphate 0.037–0.411 g / L, and a pH adjuster. This invention can be used for in vitro evaluation of the dissolution behavior of pharmaceutical formulations and is applicable to fields such as drug development and quality control.

Description

Technical Field

[0001] This invention belongs to the field of in vitro dissolution testing technology for pharmaceutical preparations, and particularly relates to a novel human simulated fasting gastric juice and its preparation method. Background Technology

[0002] Simulated gastric juice is an artificial solution used to simulate the digestive environment of the human stomach, and it is widely used in medical research, drug development, and food digestion simulation.

[0003] In existing technologies, the surface tension of simulated gastric juice is typically about 60 mN / m, the osmotic pressure is 0.029–0.191 Osm / kg, the pH value is 1.2–2.0, and the buffering capacity is 0–0.0008 mol / δpH / L. In contrast, the median surface tension of real human gastric juice is 36.85 mN / m, the median osmotic pressure is 0.257 Osm / kg, the median pH value is 1.47, and the median buffering capacity is 0.0174 mol / δpH / L.

[0004] Clearly, existing simulated gastric juices differ significantly from real fasting gastric juices in terms of surface tension, osmotic pressure, and buffering capacity, making it difficult to accurately and effectively replicate the actual fasting gastric juice environment in humans. This deviation in physicochemical properties significantly affects the dissolution and exudation behavior of drugs under in vitro experimental conditions, leading to reduced consistency between their performance and actual in vivo behavior, thus impacting the scientific validity and reference value of in vitro dissolution test results. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a novel human simulated fasting gastric juice and its preparation method, in order to solve the technical problem that existing simulated gastric juices differ significantly from real human fasting gastric juices in terms of physicochemical properties such as surface tension, osmotic pressure, and buffering capacity, which limits the accuracy of in vitro assessment of drug dissolution and leaching behavior.

[0006] The objective of this invention is mainly achieved through the following technical solutions.

[0007] This invention provides a human simulated fasting gastric juice, comprising bovine serum albumin 2-30 mg / mL, glycocholic acid or glycocholate 0-7.517E-05 mol / L, glycochenodeoxycholic acid or glycochenodeoxycholate 0-7.421E-05 mol / L, taurocholic acid or taurocholate 0-8.369E-04 mol / L, taurochenodeoxycholic acid or taurochenodeoxycholate 0-9.005E-04 mol / L, calcium chloride 0.025-0.138 g / L, potassium chloride 0.478-1.12 g / L, magnesium chloride 0.015-0.063 g / L, sodium chloride 2.05-5.26 g / L, sodium dihydrogen phosphate 0.037-0.411 g / L, and a pH adjuster.

[0008] Furthermore, the pH adjuster is hydrochloric acid.

[0009] Furthermore, the pH value of simulated fasting gastric juice in the human body is 1.15–1.74.

[0010] Furthermore, the surface tension of simulated fasting gastric juice in the human body is 38–45 mN / m.

[0011] Furthermore, the osmotic pressure of simulated fasting gastric juice in humans is 0.15–0.18 Osm / kg.

[0012] This invention also provides a method for preparing human simulated fasting gastric juice, used for the preparation of the aforementioned human simulated fasting gastric juice; the preparation method includes the following steps:

[0013] Step 1: Mix calcium chloride, potassium chloride, magnesium chloride, sodium chloride, and sodium dihydrogen phosphate in a certain proportion to obtain the first mixed powder;

[0014] Step 2: Add deionized water to the first mixed powder and stir until it is completely dissolved to obtain a mixed aqueous solution;

[0015] Step 3: Add an appropriate amount of hydrochloric acid to the mixed aqueous solution to adjust the pH value to the target range, thus obtaining the buffer solution;

[0016] Step 4: Mix bovine serum albumin, glycocholic acid or glycocholate, glycochenodeoxycholic acid or glycochenodeoxycholate, taurocholic acid or taurocholate, and taurochenodeoxycholic acid or taurochenodeoxycholate in a certain proportion to obtain a second mixed powder.

[0017] Step 5: Add the second mixed powder to the buffer solution and stir thoroughly until the mixture is homogeneous to obtain human simulated fasting gastric juice.

[0018] Furthermore, the mixing operations in steps 1 and 4 are performed at room temperature.

[0019] Furthermore, the following steps are included before step 1:

[0020] A variety of bile acids are available for screening;

[0021] Multiple bile acids were screened to obtain the target bile acid.

[0022] Furthermore, the screening process includes the following steps:

[0023] Step a: Analyze and detect bile acids in real fasting gastric juice of human body. Real fasting gastric juice of human body contains a variety of bile acids to be screened.

[0024] Step b: Preliminary screening is performed on the various bile acids to obtain the initial screening bile acids;

[0025] Step c: Dissolve the primary screened cholic acid or its salt in buffer solution and measure the surface tension of the corresponding solution;

[0026] Step d: Determine whether the surface tension of the solution corresponding to the cholic acid or its salt in the initial screening is lower than 10% of the theoretical surface tension of water;

[0027] If so, then this initial screening bile acid is determined to be the target bile acid;

[0028] If not, then this initial screening of bile acids is determined to be a non-target bile acid.

[0029] Further, the cholic acids or their salts to be screened include cholic acid, taurocholic acid, glycocholic acid, chenodeoxycholic acid, deoxycholic acid, glycodeoxycholic acid, lithocholic acid, hydrocholic acid, glycohydrocholic acid, taurohydrocholic acid, α-methylcholic acid, β-methylcholic acid, ω-methylcholic acid, tauro-ω-methylcholic acid, tauro-β-methylcholic acid, glycohydroxydeoxycholic acid, taurohydroxydeoxycholic acid, dihydrocholic acid, glycodehydrocholic acid, glycolithocholic acid, isocholic acid, 7- Ketodeoxycholic acid, 6-ketolithocholic acid, 7-ketolithocholic acid, 12-ketolithocholic acid, 23-deoxycholic acid, isolithocholic acid, tauron-α-methylcholic acid, methyldeoxycholic acid, 3-ketocholic acid, isodeoxycholic acid, ursolic acid, isursolic acid, dehydrolithocholic acid, allocholic acid, allolithocholic acid, glycochenodeoxycholic acid, tauron-chenodeoxycholic acid, ursolic acid, glycochenodeoxycholic acid, tauron-ursolic acid, and taurololithocholic acid.

[0030] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0031] A) The novel composition of the human fasting gastric fluid provided by this invention can be used to evaluate the dissolution behavior of drug formulations in the stomach under fasting conditions. This formulation is based on the elemental composition, ion concentration, surface tension, osmotic pressure, and buffering capacity of fasting gastric fluid from healthy Chinese adults. Through the rational selection of specific components and the adjustment of their dosage, various physicochemical indicators are made closer to actual physiological states, reconstructing a simulation system with physicochemical properties close to real human fasting gastric fluid. This system significantly improves the prediction accuracy and simulation precision of drug dissolution behavior in vitro, and has lower preparation costs, possessing good economic and practical value.

[0032] B) The novel composition of the human simulated fasting gastric juice provided by this invention uses bovine serum albumin (BSA) in combination with various bile acids (salts) (i.e., glycocholic acid or glycocholate, glycochenodeoxycholic acid or glycochenodeoxycholate, taurocholic acid or taurocholate, and taurochenodeoxycholic acid or taurochenodeoxycholate). Compared with the use of bovine serum albumin alone (surface tension of approximately 39 mN / m) or bile salts (surface tension range of 45–60 mN / m), it can more effectively reduce the surface tension of the simulated gastric juice. This synergistic effect is mainly attributed to the amphiphilic structural features of bovine serum albumin and bile acid or bile salt molecules, which enable them to interact with both hydrophobic and hydrophilic groups simultaneously, forming a stable complex at the liquid interface. This more efficiently reduces the surface tension of the human simulated fasting gastric juice and improves the realism and stability of the simulation system.

[0033] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained through the embodiments described and the accompanying drawings, which are particularly pointed out. Attached Figure Description

[0034] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0035] Figures 1a-1b This is a graph showing the concentrations of 12 bile acids screened in human gastric juice.

[0036] Figures 2a-2e Surface tension diagrams of solutions corresponding to the 12 cholic acids or their salts in the initial screening;

[0037] Figure 3 This is a graph showing the surface tension changes of bovine serum albumin.

[0038] Figure 4A schematic diagram of the mixing device for simulating fasting gastric juice in a human body provided by the present invention;

[0039] Figure 5 A schematic diagram of the stirring component in a low-position stirring mode in simulated fasting gastric juice of a human body, provided by the present invention.

[0040] Figure 6 This is a schematic diagram of the structure of the stirring component in a high-position stirring mode in simulated fasting gastric juice provided by the present invention.

[0041] Figure label:

[0042] 1-Premixed buffer solution chamber; 2-Powder storage chamber; 3-Dispersion nozzle; 4-Negative pressure dispersion chamber; 5-Propeller blade; 6-Stirring motor; 7-Connecting rod; 8-Sliding rod. Detailed Implementation

[0043] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0044] Dissolution testing of small molecule drug formulations is a crucial tool for formulation development, bioavailability assessment, quality control, and regulatory compliance verification. Dissolution profiles obtained from dissolution tests provide key information on the release rate and extent of the drug in a simulated gastrointestinal environment, thus reflecting its potential in vivo release behavior within the gastrointestinal tract. Combined with permeability parameters (used to characterize the ability of the active pharmaceutical ingredient to cross the intestinal epithelial cell membrane), these factors together constitute the core system for assessing potential bioavailability, providing significant guidance for formulation development. Since only dissolved drugs can cross the intestinal epithelial cell membrane and be absorbed, the permeability of the active pharmaceutical ingredient is largely limited by its physicochemical properties. Therefore, accurately characterizing in vitro dissolution behavior is fundamental to assessing the potential absorption capacity of the active pharmaceutical ingredient in a specific oral formulation.

[0045] To more accurately simulate the in vivo environment, physiologically relevant dissolution mediators, including FaSSGF, FaSSIF, and FeSSIF, have been developed in recent years. These mediators, through surfactants such as bile acids, simulate the gastric juice and intestinal fluid environments under fasting and full states, and are widely used in predictive studies of in vivo dissolution behavior.

[0046] In fact, gastric juice contains pepsin and other proteins, which significantly reduce surface tension, thus affecting drug dissolution. Therefore, dissolution media used to simulate gastric juice should appropriately contain these components to more realistically reflect in vivo dissolution characteristics.

[0047] In a first aspect, the present invention provides a human simulated fasting gastric juice, comprising bovine serum albumin (BSA) 2-30 mg / mL, glycocholic acid or glycocholate 0-7.517E-0.5 mol / L, glycochenodeoxycholic acid or glycochenodeoxycholate 0-7.421E-0.5 mol / L, taurocholic acid or taurocholate 0-8.369E-0.4 mol / L, and taurochenodeoxycholic acid or taurochenodeoxycholic acid... The mixture contains bile salts of 0–9.005E-04 mol / L, calcium chloride of 0.025–0.138 g / L, potassium chloride of 0.478–1.12 g / L, magnesium chloride of 0.015–0.063 g / L, sodium chloride of 2.05–5.26 g / L, sodium dihydrogen phosphate of 0.037–0.411 g / L, and a pH adjuster (e.g., hydrochloric acid), wherein the pH of the simulated fasting gastric juice is 1.15–1.74.

[0048] For example, the buffer solution used in the above-mentioned simulated fasting gastric juice of human body has the following specific composition: calcium chloride 0.072 g / L, potassium chloride 0.83 g / L, magnesium chloride 0.037 g / L, sodium chloride 3.00 g / L, sodium dihydrogen phosphate 0.20 g / L, pH up to 1.6 ± 0.05, and buffering capacity of 0.0179 mol / δpH / L.

[0049] Compared to existing commercially available fasted state simulated gastric fluid (FaSSGF), the human simulated fasted gastric fluid provided by this invention can be used to evaluate the dissolution behavior of drug formulations in the stomach under fasting conditions. This formulation is based on the elemental composition, ion concentration, surface tension, osmotic pressure, and buffering capacity of fasted gastric fluid from healthy Chinese adults. By selecting specific components and adjusting the amount added, various indicators are made closer to the actual physiological state, reconstructing a simulation system with physicochemical properties close to real human fasted gastric fluid. This can significantly improve the prediction accuracy and simulation precision of drug dissolution behavior in vitro, while also having a lower cost advantage.

[0050] It is worth noting that the human simulated fasting gastric juice of this invention uses bovine serum albumin (BSA) in combination with bile acids or bile salts (i.e., glycocholic acid or glycocholate, glycochenodeoxycholic acid or glycochenodeoxycholate, taurocholic acid or taurocholate, and taurochenodeoxycholic acid or taurochenodeoxycholate). Compared with using bovine serum albumin alone (surface tension approximately 39 mN / m) or bile acids alone (surface tension range 45–60 mN / m), this method is more effective in reducing the surface tension of the simulated gastric juice. This synergistic effect is mainly attributed to the amphiphilic structural characteristics of bovine serum albumin and bile acid molecules, which allow them to interact with both hydrophobic and hydrophilic groups simultaneously, forming a complex at the liquid interface. This more efficiently reduces the surface tension of the human simulated fasting gastric juice, improving the realism and stability of the simulation system.

[0051] In a second aspect, the present invention provides a method for preparing human simulated fasting gastric juice, which is used in the preparation of the human simulated fasting gastric juice provided in the first aspect.

[0052] Specifically, the above preparation method includes the following steps:

[0053] Step 1: Mix calcium chloride, potassium chloride, magnesium chloride, sodium chloride, and sodium dihydrogen phosphate in a certain proportion to obtain the first mixed powder;

[0054] Step 2: Add deionized water to the first mixed powder and stir until it is completely dissolved to obtain a mixed aqueous solution;

[0055] Step 3: Add an appropriate amount of hydrochloric acid to the mixed aqueous solution to adjust the pH value to the target range, thus obtaining the buffer solution;

[0056] Step 4: Mix bovine serum albumin, glycocholic acid or glycocholate, glycochenodeoxycholic acid or glycochenodeoxycholate, taurocholic acid or taurocholate, and taurochenodeoxycholic acid or taurochenodeoxycholate in a certain proportion to obtain a second mixed powder.

[0057] Step 5: Add the second mixed powder to the buffer solution and stir thoroughly until the mixture is homogeneous to obtain human simulated fasting gastric juice.

[0058] To ensure the complete dissolution of each component, for example, the mixing temperature in steps 1 and 4 above is 20 to 30°C (e.g., 25°C).

[0059] In order to obtain accurate values ​​of the parameters of real fasting gastric juice in the human body, and to more reasonably adjust the range of various parameters of simulated fasting gastric juice in the human body, the following steps are included before step 1 above:

[0060] Step A: Collect real fasting gastric juice from a human body;

[0061] Step B: Divide the actual fasting gastric juice of a human body into multiple samples, such as the first sample, the second sample, the third sample, and the fourth sample;

[0062] Step C: Mix the first sample with the protease inhibitor and then determine the protein content;

[0063] The pH value of the second sample was measured using a pH meter.

[0064] The buffering capacity of the third sample was determined by titration with 0.1N NaOH.

[0065] The osmotic pressure of the fourth sample was determined using an osmometer and the freezing point depression method.

[0066] The fifth sample was tested for ion concentration (ions included Ca, P, Na, K, Cl, Fe, and Mg);

[0067] The surface tension of the sixth sample was measured using the pendant drop method at room temperature (e.g., 20°C).

[0068] In this way, each sample is used for the determination of a single parameter, which can prevent cross-contamination and ensure the accuracy and reliability of the analysis.

[0069] In order to obtain specific types of bile acids and to reasonably adjust the surface tension and osmotic pressure of simulated fasting gastric juice in humans, so that these two parameters are closer to those of real fasting gastric juice in humans, the following steps are included before step 1:

[0070] A variety of bile acids are available for screening, including cholic acid (CA), taurocholic acid (TCA), glycocholic acid (GCA), chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), glycocodeoxycholic acid (GDCA), lithocholic acid (LCA), hydrocholic acid (HCA), glyco-hydrocholic acid (GHCA), and tauro-hydrocholic acid (THA). Acids (THCA), α-methylcholic acid (α-MCA), β-methylcholic acid (β-MCA), ω-methylcholic acid (ω-MCA), tauro-ω-Methylcholic acid (T-ω-MCA), tauro-β-Methylcholic acid (T-β-MCA), glyco-hydroxydeoxycholic acid (GHDCA), tauro-hydroxydeoxycholic acid (THDCA), dihydrocholic acid Acids including DHCA, Glycodehydrocholic Acid (GDHCA), Glycolithocholic Acid (GLCA), Allocholic Acid (ACA), 7-Ketodeoxycholic Acid (7-KDCA), 6-Keto-Lithocholic Acid (6-KLCA), 7-Keto-Lithocholic Acid (7-KLCA), 12-Keto-Lithocholic Acid (12-KLCA), 23-Deoxycholic Acid (23-NDCA), Iso-Lithocholic Acid (Iso-LCA), and Tauro-α-Methylcholic Acid (Tauro-α-Methylcholic Acid).T-α-MCA, Methyl-Deoxycholic Acid (MDCA), 3-Ketocholic Acid (3-KCA), Iso-Deoxycholic Acid (Iso-DCA), Ursocholic Acid (UCA), Iso-Ursodeoxycholic Acid (Iso-UDCA), Dehydro-Lithocholic Acid (DLCA), Allocholic Acid (allo-CA), Allo-Lithocholic Acid (allo-LCA), Glycochenodeoxycholic Acid (GCDCA), Taurochenodeoxycholic Acid (TCDCA), Ursodeoxycholic Acid (Ursodeoxycholic Acid) Acids including UDCA, glycoursodeoxycholic acid (GUDCA), tauroursodeoxycholic acid (TUDCA), and tauro-lithocholic acid (TLCA);

[0071] The provided bile acids were screened to obtain the target bile acid.

[0072] Specifically, the screening process includes the following steps:

[0073] Step a: Test the bile acids in real fasting gastric juice of human beings. Real fasting gastric juice of human beings contains a variety of bile acids to be screened.

[0074] Step b: Select preliminary cholic acids from a variety of cholic acids to be screened (e.g., 42). The preliminary cholic acids are glycocholic acid (GCA), glycoursodeoxycholic acid (GUDCA), glycocodeoxycholic acid (GDCA), taurocholic acid (TCA), taurochenodeoxycholic acid (TCDCA), cholic acid (CA), chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), glycolithocholic acid (GLCA), tauro-lithocholic acid (TLCA), and tauro-ursodeoxycholic acid (TDCA). Acid (TUDCA) and glycochenodeoxycholic acid (GCDCA), for example, the initial screening showed that the content of bile acid in real fasting gastric juice of a human body was greater than 1 ng / mL, see [link to relevant documentation]. Figures 1a to 1b ;

[0075] Step b: Dissolve the primary screening bile acids in buffer solution and measure the surface tension of multiple primary screening bile acids;

[0076] Step c: Determine whether the surface tension of the initial screening cholic acid is less than 10% of the theoretical surface tension of water;

[0077] If so, then this initial screening bile acid is determined to be the target bile acid, and the target bile acids are GCA, GCDCA, TCA and TCDCA;

[0078] If not, then the bile acid in this initial screening is determined to be a non-target bile acid. Non-target bile acids include CA, CDCA, DCA, GDCA, GLCA, GUDCA, TLCA, and TUDCA.

[0079] This is because, see Figure 2a CA, CDCA, DCA, GDCA, GLCA, GUDCA, TLCA, and TUDCA, even at concentrations far above physiological levels, still exhibit limited ability to reduce surface tension, with their surface tension approaching that of deionized water. See also Figures 2b to 2eGCA, GCDCA, TCA, and TCDCA exhibited relatively strong surface tension reduction capabilities. Among them, GCA and GCDCA achieved maximum surface tension reduction near their saturation concentrations (34 μg / mL and 37 μg / mL, respectively), but their surface tensions remained above 60 mN / m and 50 mN / m, respectively (see [reference needed]). Figure 2b and 2c In contrast, TCA and TCDCA have higher solubility and exhibit better surface activity, reducing surface tension to 60 mN / m and 45 mN / m, respectively (see...). Figure 2d and Figure 2e However, these values ​​are still higher than the actual surface tension level of human gastric juice. Therefore, introducing protein components into the dissolution medium is crucial for further reducing surface tension; even at concentrations as low as 20 mg / mL, bovine serum albumin (BSA) significantly reduces surface tension, bringing it closer to the level of real gastric juice (see [link to dissolution medium]). Figure 3 ).

[0080] It is worth noting that traditional mixing methods suffer from powder agglomeration, making it difficult for bovine serum albumin and bile acids or bile salts to mix evenly with the buffer solution. Therefore, in step 5 above, a mixing device with the following structure is used to achieve thorough mixing of the powder and the buffer solution:

[0081] See Figure 4 The mixing device includes a premixed buffer tank 1, a powder storage tank 2, a dispersing nozzle 3, a negative pressure dispersing chamber 4, and a main mixing chamber (not shown in the figure). The powder storage tank 2, the dispersing nozzle 3, and the negative pressure dispersing chamber 4 are sequentially and sealed together. The outlet of the premixed buffer tank 1 is sealed to the inlet of the negative pressure dispersing chamber 4, and the outlet of the negative pressure dispersing chamber 4 is sealed to the main mixing chamber. It should be noted that the negative pressure value in the negative pressure dispersing chamber 4 is low, only enough to ensure that the second mixed powder can be sprayed into the negative pressure dispersing chamber 4 through the dispersing nozzle 3. In this way, the above mixing device is based on the "dispersion feeding + premixing" method. Through multi-channel fluid cutting, negative pressure adsorption dispersion, and vortex premixing, the second mixed powder is initially dispersed before contacting the premixed buffer. After adding the premixed buffer, it is easier to mix evenly. After the premixed liquid composed of the premixed second mixed powder and the premixed buffer is supplied to the main mixing chamber, it is equivalent to mixing two liquids, thereby achieving uniform mixing.

[0082] Specifically, the structure of the powder storage bin 2 includes a cylindrical section and an inverted conical section connected sequentially from top to bottom. A vibrator is installed on the side wall of the inverted conical section, and the second mixed powder is contained within the powder storage bin 2. In this way, the periodic vibration of the vibrator promotes the smooth falling of the second mixed powder, preventing bridging.

[0083] Specifically, the structure of the dispersing nozzle 3 includes a nozzle body and multiple powder guiding channels disposed within the nozzle body, which are arranged in a spiral shape. In this way, powder falls from the powder storage chamber 2 into the nozzle body and flows along the powder guiding channels. Under the action of negative pressure within the negative pressure dispersing chamber 4, it is cut into fine powder streams by multiple high-speed airflows, achieving initial dispersion.

[0084] Specifically, the structure of the negative pressure dispersion chamber 4 is located below the dispersion nozzle 3 and includes a chamber body and a negative pressure fan. The air inlet of the negative pressure fan is connected to the inner cavity of the chamber body. The negative pressure fan creates a negative pressure in the inner cavity of the chamber body. The negative pressure can further adsorb and disperse the second mixed powder sprayed from the dispersion nozzle 3, preventing the powder from agglomerating again.

[0085] In order to further improve the dispersibility of the second mixed powder, the negative pressure dispersion chamber 4 also includes an ultrasonic generator to generate ultrasonic waves in the inner cavity of the chamber, and to use the ultrasonic cavitation effect to assist the dispersion of the second mixed powder.

[0086] To ensure thorough mixing of the second mixed powder and premixed buffer solution within the negative pressure dispersion chamber 4, the chamber also includes a stirring assembly. A tangential inlet is located on the side wall of the chamber, through which the premixed buffer solution in the mixing buffer chamber is supplied. When the dispersed second mixed powder enters the chamber, the premixed buffer solution flows in at high speed from the tangential inlet, creating a strong vortex field under the action of the stirring assembly, thus premixing the second mixed powder.

[0087] Specifically, the structure of the stirring assembly includes a propeller blade 5 and a stirring motor 6 for driving the propeller blade 5 to rotate.

[0088] Considering that the premixed buffer solution in the negative pressure dispersion chamber 4 gradually increases during the premixing process, and the second mixed powder comes into contact with the upper premixed buffer solution first, in order to adjust the stirring height of the stirring assembly according to the liquid level of the premixed buffer solution, specifically, the stirring assembly also includes two connecting rods 7 and a sliding rod 8. The propeller blade 5 is sleeved on the bottom of the outer wall of the sliding rod 8 and fixedly connected to it. The top of the sliding rod 8 is higher than the top of the propeller blade 5. Two blind holes are opened on the side of the sliding rod 8 facing the connecting rod 7. One end of the connecting rod 7 is fixedly connected to the output shaft of the stirring motor 6, and the other end is inserted into the blind hole and slidably connected to the sliding rod 8. The stirring motor 6 drives the propeller blade 5 to rotate through the connecting rod 7 and the sliding rod 8. The stirring assembly has a low-level stirring mode and a high-level stirring mode. When the stirring assembly is in low-level stirring mode, see... Figure 5The premixed buffer in the negative pressure dispersion chamber 4 is relatively small. The propeller blade 5 is below the liquid surface in the negative pressure dispersion chamber 4, and part of the sliding rod 8 is above the liquid surface in the negative pressure dispersion chamber 4. The buoyancy of the premixed buffer on the sliding rod 8 is small. The top of the connecting rod 7 is in contact with the bottom of the blind hole. The propeller blade 5 stirs the premixed buffer in the lower part of the negative pressure dispersion chamber 4. When the stirring assembly is in high-level stirring mode, see... Figure 6 Both the propeller blade 5 and the sliding rod 8 are below the liquid surface in the negative pressure dispersion chamber 4. The buoyancy of the premixed buffer solution on the sliding rod 8 increases, causing the sliding rod 8 to float upwards. The top of the connecting rod 7 does not contact the bottom of the blind hole. At the same time, when the stirring assembly is in the low-position stirring mode, the rotation speed of the propeller blade 5 is the first rotation speed. When the stirring assembly is in the high-position stirring mode, the rotation speed of the propeller blade 5 is the second rotation speed. The second rotation speed is greater than the first rotation speed, and the upward force generated by the propeller blade 5 increases, which also causes the sliding rod 8 to float upwards. The propeller blade 5 stirs the premixed buffer solution in the middle or upper part of the negative pressure dispersion chamber 4.

[0089] The composition and performance parameters of the simulated fasting gastric juice in Examples 1 to 12 of the present invention are shown in Table 1.

[0090] Table 1. Composition and performance parameters of simulated fasting gastric juice in humans.

[0091]

[0092]

[0093] Furthermore, the bile acids or their salts used in the experiments of this study, under strongly acidic conditions of pH 1.0-2.0, typically exist in undissociated acidic form because their pKa is usually in the range of 5.0-6.0. Therefore, the scope of protection of this invention includes the bile acids and their corresponding salts. Given the potential differences in chemical names and terminology between Chinese and English, especially the potential for confusion between terms such as "deoxygenation" and "deoxygenated" in different contexts, the chemical names described herein are based on their original English names to ensure accuracy and consistency in terminology.

[0094] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing human simulated fasting gastric juice, characterized in that, This preparation is used to simulate human fasting gastric juice, which includes bovine serum albumin 2-30 mg / mL, glycocholic acid or glycocholate 0-7.517E-0.5 mol / L, glycochenodeoxycholic acid or glycochenodeoxycholate 0-7.421E-0.5 mol / L, taurocholic acid or taurocholate 0-8.369E-0.4 mol / L, taurochenodeoxycholic acid or taurochenodeoxycholate 0-9.005E-0.4 mol / L, calcium chloride 0.025-0.138 g / L, potassium chloride 0.478-1.12 g / L, magnesium chloride 0.015-0.063 g / L, sodium chloride 2.05-5.26 g / L, and sodium dihydrogen phosphate 0.037-0.411 g / L. The preparation method includes the following steps: Step 1: Mix calcium chloride, potassium chloride, magnesium chloride, sodium chloride and sodium dihydrogen phosphate in a certain proportion to obtain a first mixed powder; Step 2: Add deionized water to the first mixed powder and stir to completely dissolve it to obtain a uniform mixed aqueous solution; Step 3: Add hydrochloric acid to the mixed aqueous solution to adjust the pH value to the target range to obtain a buffer solution; Step 4: Mix bovine serum albumin, glycocholic acid or glycocholate, glycochenodeoxycholic acid or glycochenodeoxycholate, taurocholic acid or taurocholate, taurochenodeoxycholic acid or taurochenodeoxycholate in a certain proportion to obtain a second mixed powder; Step 5: Add the second mixed powder to the buffer solution obtained in Step 3 and mix evenly using a mixing device to obtain human simulated fasting gastric juice; The mixing device includes a premixed buffer solution chamber, a powder storage chamber, and a dispersion chamber. The nozzle, negative pressure dispersion chamber, and main mixing chamber are sequentially and sealed together. The outlet of the premixed buffer chamber is sealed to the inlet of the negative pressure dispersion chamber, and the outlet of the negative pressure dispersion chamber is sealed to the main mixing chamber. The negative pressure dispersion chamber includes a stirring assembly, which includes a propeller blade, a stirring motor, two connecting rods, and a sliding rod. The propeller blade is fitted onto the bottom of the outer wall of the sliding rod and is fixedly connected to it. The top of the sliding rod is higher than the top of the propeller blade. Two blind holes are opened on the side of the sliding rod facing the connecting rod. One end of the connecting rod is fixedly connected to the output shaft of the stirring motor, and the other end is inserted into the blind holes and slidably connected to the sliding rod. The stirring assembly has a low-level stirring mode and a high-level stirring mode. In the low-level stirring mode, the rotation speed of the propeller blade is the first rotation speed. In the high-level stirring mode, the rotation speed of the propeller blade is the second rotation speed, which is greater than the first rotation speed.

2. The method for preparing simulated fasting gastric juice according to claim 1, characterized in that, The pH adjuster is hydrochloric acid.

3. The method for preparing simulated fasting gastric juice according to claim 1, characterized in that, The pH value of the simulated fasting gastric juice is 1.15~1.

74.

4. The method for preparing simulated fasting gastric juice according to claim 1, characterized in that, The surface tension of the simulated fasting gastric juice in the human body is 38~45 mN / m.

5. The method for preparing simulated fasting gastric juice according to claim 1, characterized in that, The osmotic pressure of the simulated fasting gastric juice in the human body is 0.15~0.18 Osm / kg.

6. The method for preparing simulated fasting gastric juice according to claim 1, characterized in that, The mixing operations in steps 1 and 4 are performed at room temperature.

7. The method for preparing simulated fasting gastric juice according to claim 1, characterized in that, The following steps are included before step 1: A variety of bile acids are available for screening; The various bile acids to be screened are screened to obtain the target bile acid.

8. The method for preparing simulated fasting gastric juice according to claim 7, characterized in that, The screening process includes the following steps: Step a: Analyze and detect the various bile acids contained in real fasting gastric juice in humans; Step b: Preliminary screening is performed on the various bile acids to obtain the initial screening bile acids; Step c: Dissolve the primary screened cholic acid or its salt in buffer solution and measure the surface tension of the corresponding solution; Step d: Determine whether the surface tension of the solution corresponding to the cholic acid or its salt in the initial screening is less than 10% of the theoretical surface tension of water; If so, then this initial screening bile acid is determined to be the target bile acid; If not, then this initial screening of bile acids is determined to be a non-target bile acid.

9. The method for preparing simulated fasting gastric juice according to claim 7, characterized in that, The cholic acids to be screened include cholic acid, taurocholic acid, glycocholic acid, chenodeoxycholic acid, deoxycholic acid, glycodeoxycholic acid, lithocholic acid, hydrocholic acid, glycohydrocholic acid, taurohydrocholic acid, α-methylcholic acid, β-methylcholic acid, ω-methylcholic acid, tauro-ω-methylcholic acid, tauro-β-methylcholic acid, glycohydroxydeoxycholic acid, taurohydroxydeoxycholic acid, dihydrocholic acid, glycodehydrocholic acid, glycolithocholic acid, isocholic acid, and 7-ketocholic acid. Oxycholic acid, 6-ketolithocholic acid, 7-ketolithocholic acid, 12-ketolithocholic acid, 23-deoxycholic acid, isolicholic acid, taurine-α-methylcholic acid, methyldeoxycholic acid, 3-ketocholic acid, isodeoxycholic acid, ursolic acid, isursolic acid, dehydrolithocholic acid, allo-cholic acid, allo-lithocholic acid, glycochenodeoxycholic acid, taurinechenodeoxycholic acid, ursolic acid, glycochenodeoxycholic acid, taurinechenodeoxycholic acid, and taurinelithocholic acid.

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