A retinoic acid alcohol amine complex, its preparation method and application

Abstract

This invention relates to a retinoic acid-alcohol amine complex, which is composed of retinoic acid and an alcohol amine compound. It is in liquid form at room temperature and has good water solubility / water dilution resistance and skin penetration effect. It overcomes the limitations of retinoic acid compounds in the field of pharmaceutical application in the prior art and has broad pharmaceutical prospects.

Description

Technical Field

[0001] This invention belongs to the field of medicinal chemistry, specifically relating to a retinoic acid alcohol amine complex, its preparation method, and its application. Background Technology

[0002] Vitamin A and its metabolites play important roles in the human body and are currently widely used to treat various diseases. For example, retinoic acid (molecular formula C36-4 ... 20 H 28 O2 (vitamin O2) primarily affects bone growth and promotes epithelial cell proliferation, differentiation, and keratinization. Retinoic acid is mainly used to treat acne vulgaris, hyperpigmentation, photoaging, psoriasis, ichthyosis, lichen planus, pityriasis rubra pilaris, keratosis pilaris, squamous cell carcinoma, and melanoma. Oral retinoic acid can also be used to treat acute promyelocytic leukemia.

[0003] Retinoic acid is lipid-soluble and almost insoluble in water, resulting in poor solubility in formulations and in vivo dissolution, which limits its pharmaceutical applications. Furthermore, due to the barrier function of the stratum corneum, only a small amount of conventional topical retinoic acid formulations can penetrate the barrier to exert their effects, making it difficult to maintain an effective therapeutic concentration. Increasing the dosage of retinoic acid, however, can lead to significant skin irritation, such as varying degrees of redness, stinging, and edema. Given the promising application prospects of retinoic acid in the treatment of skin diseases, it is necessary to develop it into a pharmaceutical form suitable for use in skin conditions. Summary of the Invention

[0004] In order to improve the technical problems existing in the prior art, in a first aspect, the present invention provides a retinoic acid alcohol amine complex, the complex being composed of retinoic acid and alcohol amine compounds.

[0005] According to an embodiment of the present invention, the alkanolamine compound is selected from the following formula I:

[0006]

[0007] Where X is selected from C 1-6 Alkyl groups, preferably selected from -CH2-CH2-, -CH2-CH2-CH2- and R1 and R2 are each independently selected from H and C. 1-6 Alkyl, C 1-6 Alkyl-OH.

[0008] According to an embodiment of the present invention, Formula I is selected from diethanolamine, triethanolamine, monoethanolamine (2-hydroxyethylamine), N-methyldiethanolamine, n-propanolamine, isopropanolamine, diisopropanolamine, triisopropanolamine, n-butanolamine, dibutanolamine, and isobutanolamine.

[0009] According to an embodiment of the present invention, the molar ratio of the alkanolamine compound to retinoic acid is (1-100):1, for example, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, (1-10):1, more preferably (1-5):1.

[0010] According to embodiments of the present invention, the complex is in liquid form at room temperature. In the complex, the retinoic acid may be present partially or entirely in anionic form, and the alkanolamine compound may be present partially or entirely in cationic form. In some embodiments, in the complex, a portion of the retinoic acid is present in molecular form and / or a portion of the alkanolamine compound is present in molecular form.

[0011] In some embodiments, retinoic acid is present in the complex as follows [A] - [Form exists:]

[0012]

[0013] In some embodiments, the complex contains an alkanolamine compound as shown in Formula II [B] + [Form exists:]

[0014]

[0015] In Equation II, X' is selected from C 1-6 Alkyl groups, preferably selected from -CH2-CH2-, -CH2-CH2-CH2- and R1' and R2' are each independently selected from H and C. 1-6 Alkyl, C 1-6 Alkyl-OH.

[0016] According to an embodiment of the present invention, Formula II is selected from diethanolammonium cation, triethanolammonium cation, monoethanolammonium cation (i.e., 2-hydroxyethylammonium cation), N-methyldiethanolammonium cation, n-propanolammonium cation, isopropanolammonium cation, diisopropanolammonium cation, triisopropanolammonium cation, n-butanolammonium cation, dibutanolammonium cation, and isobutanolammonium cation.

[0017] In some embodiments, the complex is [A] - [B] + ] x The x can be selected from 1 to 10, for example, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7.

[0018] In a second aspect, the present invention provides a method for preparing the complex, comprising the following steps: reacting retinoic acid with the alkanolamine compound to obtain the complex.

[0019] According to an embodiment of the present invention, the molar ratio of the alkanolamine compound and retinoic acid is (1-100):1, for example, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, (1-10):1, more preferably (1-5):1.

[0020] According to embodiments of the present invention, the reaction reagent can be water, an organic solvent, or a mixture of an organic solvent and water, wherein the organic solvent is selected from one or more combinations of ethanol, methanol, and acetone. Preferably, the organic solvent is ethanol.

[0021] According to an embodiment of the present invention, the volume ratio of organic solvent to water in the mixed solvent is 5:95 to 95:5. Preferably, the volume ratio of organic solvent to water in the mixed solvent is 40:60 to 95:5.

[0022] According to an embodiment of the present invention, the reaction can be carried out by dry grinding.

[0023] According to an embodiment of the present invention, the total amount ratio of retinoic acid to the reaction reagent is 1g:5-150mL, preferably 1g:5-20mL.

[0024] According to an embodiment of the present invention, the preparation method includes the following steps:

[0025] (1) Add the reaction reagent to the retinoic acid and stir to mix;

[0026] (2) Add the reaction reagent to the alcohol amine compound and stir to dilute;

[0027] (3) Add the diluted solution obtained in step (2) to the mixture obtained in step (1).

[0028] According to an embodiment of the present invention, in step (1), the ratio of retinoic acid to reaction reagent is 1g: 5-100mL, preferably 1g: 5-20mL; in step (2), the ratio of alkanolamine compound to reaction reagent is 1g: 0.5-50mL, preferably 1g: 0.5-5mL, more preferably 1g: 0.5-1mL.

[0029] According to an embodiment of the present invention, the preparation method further includes the steps of removing the reaction reagents and vacuum drying after the reaction is completed.

[0030] Thirdly, the present invention also provides a composition comprising the retinoic acid alcohol amine complex.

[0031] Fourthly, the present invention provides the use of the retinoic acid alcohol amine complex or the composition in the preparation of formulations, including but not limited to pharmaceutical preparations, cosmetics, care products, and beauty products.

[0032] The pharmaceutical preparation is used for the treatment of skin diseases and non-skin tumors. Preferably, the pharmaceutical preparation is used to treat skin diseases, such as acne, hyperpigmentation, photoaging, psoriasis, ichthyosis, lichen planus, pityriasis rubra pilaris, keratosis pilaris, squamous cell carcinoma, and melanoma. In some embodiments, the pharmaceutical preparation is used to treat non-skin tumors, such as acute promyelocytic leukemia, and can also be used to treat gastric cancer, lung cancer, ovarian cancer, cervical cancer, neuroblastoma, glioma, etc.

[0033] According to embodiments of the present invention, the formulation can be applied topically through the skin, for example, by means of creams, patches, ointments, lotions, gels, and sprays, or orally (i.e., oral formulations), for example, by means of tablets, granules, capsules, oral liquid formulations, pills, suspensions, drops, etc. The formulation further includes a physiologically acceptable carrier (e.g., a biocompatible material), optionally including surfactants, excipients, humectants, emulsifiers, suspending agents, salts or buffers for adjusting osmotic pressure, colorants, fragrances, stabilizers, bactericides, preservatives, or other conventional supplements.

[0034] According to embodiments of the present invention, the administration route of the formulation includes, but is not limited to, gastrointestinal administration or non-gastrointestinal administration; wherein, the gastrointestinal administration may be oral administration; and the non-gastrointestinal administration may be transdermal administration, etc.

[0035] Beneficial effects of the present invention

[0036] This invention unexpectedly discovered that retinoic acid and alkanolamine compounds can form a complex in a liquid state at room temperature, exhibiting excellent water solubility / resistance to water dilution and good skin penetration. This overcomes the limitations of existing retinoic acid compounds in pharmaceutical applications and shows broad pharmaceutical potential. The preparation method used in this study is simple and easy to implement, without harsh reaction conditions, and is easy to control in terms of quality and scale up for production. Furthermore, the solvent used can be recycled and reused, which aligns with the principles of green chemistry. Attached Figure Description

[0037] Figure 1 This is the HNMR spectrum of retinoic acid.

[0038] Figure 2This is the HNMR spectrum of diethanolamine.

[0039] Figure 3 The image shows the HNMR spectrum of the complex 2[DEA][RA].

[0040] Figure 4 The IR spectra of retinoic acid, diethanolamine, and complex 2[DEA][RA].

[0041] Figure 5 IR spectra of retinoic acid diethanolamine complexes with different molar ratios ([RA]:[DEA] = 1:2, 1:2.5, 1:3, 1:4).

[0042] Figure 6 Raman spectra of retinoic acid, diethanolamine, and complex 2[DEA][RA].

[0043] Figure 7 DVS for complex 2[DEA][RA].

[0044] Figure 8 PLM images before and after complex 2[DEA][RA]DVS.

[0045] Figure 9 The DSC of complex 2[DEA][RA].

[0046] Figure 10 It is a complex 2[DEA][RA]mDSC.

[0047] Figure 11 The properties of complex 2[DEA][RA] with different water contents.

[0048] Figure 12 The liquid nitrogen freezing test process for complex 2[DEA][RA].

[0049] Figure 13 The 1H NMR spectrum of the complex 2.5[DEA][RA].

[0050] Figure 14 HNMR spectrum of complex 3[DEA][RA]

[0051] Figure 15 (a) Illustration 7 [TEA][RA] cannot form a complex (solid precipitates, cloudy state); (b) Illustration 8 [TEA][RA] can form a complex (reddish-brown transparent liquid). Detailed Implementation

[0052] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0053] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0054] Instruments and testing conditions:

[0055]

[0056] Unless otherwise stated, percentages “%” in the following examples represent percentages by mass.

[0057] Example 1: Preparation of retinoic acid-diethanolamine complex

[0058] 1.1 Raw materials and reagents: Retinoic acid (RA) (AR, Shanghai Aladdin Biochemical Technology Co., Ltd.), diethanolamine (DEA) (AR, Sinopharm Chemical Reagent Co., Ltd.), ethanol (AR, Sinopharm Chemical Reagent Co., Ltd.).

[0059] 1.2 Preparation process of retinoic acid-diethanolamine complex

[0060] 1.2.1 Preparation Method 1

[0061] prescription

[0062]

[0063] (1) Weigh the retinoic acid according to the prescription and place it in a round-bottom flask. Add ethanol and stir to mix. The retinoic acid cannot be completely dissolved and is in a suspended state. Wrap the round-bottom flask with aluminum foil to block the light.

[0064] (2) Weigh the diethanolamine according to the prescription amount, place it in a container wrapped in aluminum foil, add ethanol and stir to dilute.

[0065] Add the diethanolamine dilution obtained in step (2) dropwise to the mixture obtained in step (1) while stirring; and wash the container with about 5 ml of ethanol and add it to the flask and stir.

[0066] After all the ingredients have been added, the solution should be a clear, orange-red color; continue stirring for 4 hours.

[0067] Solvent removal was performed using a rotary evaporator: vacuum (display): -0.095 MPa; programmed temperature rise was used to prevent ethanol boiling and splashing; rotary evaporation was performed at 45°C for 1 hour, then increased to 50°C and continued for 1 hour, then increased to 60°C and continued for 2 hours. A reddish-brown viscous liquid was obtained, which was aspirated while hot and then vacuum dried in a vacuum drying oven at 60°C for 48 hours. The resulting sample was sealed and stored in a light-proof container.

[0068] 1.2.2 Preparation Method Two

[0069] prescription:

[0070]

[0071]

[0072] Process:

[0073] Weigh out the prescribed amount of retinoic acid and place it in a round-bottom flask. Add ethanol / water and stir to mix. The retinoic acid cannot be completely dissolved and will be in a suspension. Cover the round-bottom flask with aluminum foil to block out light.

[0074] Weigh the prescribed amount of diethanolamine, place it in a foil-wrapped container, and add ethanol / water to dilute it.

[0075] Add the diluted diethanolamine solution dropwise to the round-bottom flask containing the retinoic acid mixture while stirring. Rinse the container with approximately 5 ml of ethanol / water and add it to the flask, stirring constantly. After all the solution has been added, it should be a clear, orange-red color. Continue stirring for 4 hours. Remove the solvent using a rotary evaporator. A reddish-brown viscous liquid is obtained; remove it while hot and continue vacuum drying at 60°C for 48 hours. Store the resulting sample in a sealed container protected from light.

[0076] 1.2.3 Preparation Method Three

[0077] prescription:

[0078]

[0079] Process:

[0080] Weigh the prescribed amount of diethanolamine and place it in a round-bottom flask. Wrap the round-bottom flask with aluminum foil to block out light.

[0081] Add the prescribed amount of water to a round-bottom flask and stir until homogeneous. Weigh the prescribed amount of retinoic acid and carefully add the powder to the flask in portions while stirring. Stir until the solution becomes clear, then continue stirring for 4 hours. Remove the solvent using a rotary evaporator. A reddish-brown viscous liquid is obtained; aspirate it while hot and continue vacuum drying at 60°C for 48 hours. Store the resulting sample in a sealed, light-protected container.

[0082] 1.2.4 Preparation Method Four

[0083] prescription:

[0084]

[0085]

[0086] Process:

[0087] The experiment should be conducted in the dark. Weigh out the prescribed amount of retinoic acid and place it in a crucible; then add the prescribed amount of diethanolamine. Carefully mix the two substances thoroughly using a fine grinding pestle. Place the crucible in a heating mantle and maintain the temperature at 60–80°C. Continue stirring and grinding until a reddish-brown viscous liquid is formed. Transfer the hot mixture to a light-proof container, cool, and then seal for storage.

[0088] 1.3 Preparation of retinoic acid diethanolamine complexes with different proportions

[0089] Referring to the preparation process in 1.2.1, complexes were prepared using different ratios of retinoic acid and diethanolamine (as shown in the table below). The results showed that retinoic acid and diethanolamine could form complexes (all of which were clear reddish-brown liquids at room temperature) in molar ratios of 2:1 to 10:1.

[0090] Table A-1 Complexes formed by retinoic acid and diethanolamine in different proportions

[0091] 1.4 Characterization of the retinoic acid diethanolamine complex

[0092] Experimental objective: By analyzing the nuclear magnetic resonance (NMR) 1H spectrum, infrared spectrum, and Raman spectrum of the raw materials and the retinoic acid diethanolamine complex, it can be determined that the substance formed between retinoic acid and diethanolamine is not a simple physical mixture, but rather involves intermolecular interactions, with ionic and hydrogen bonds present. This constitutes the chemical basis for the unique physicochemical properties of the retinoic acid complex.

[0093] 1.4.1 Proton nuclear magnetic resonance (HNMR) spectrum

[0094] The 1H NMR spectrum of retinoic acid, diethanolamine, and the prepared retinoic acid-diethanolamine complex (2[DEA][RA]) was used for identification, such as... Figures 1 to 3 And as shown in the table below:

[0095] Table A-2 Characteristic hydrogen atom chemical shifts

[0096]

[0097] The results showed that the active hydrogen atom of retinoic acid disappeared in the ¹H NMR of 2[DEA][RA], indicating that retinoic acid interacted with diethanolamine. The chemical shift of the hydrogen atom ortho to the carboxyl group of retinoic acid shifted to a higher field, from 7.02 to 6.78, indicating that retinoic acid acted as a proton donor in the complex system, undergoing anionization, with the carboxyl oxygen atom as the charge center. Both methylene hydrogen pairs of diethanolamine showed chemical shifts to a lower field, from 2.58 to 2.76 and from 3.46 to 3.56, respectively; indicating that diethanolamine acted as a proton acceptor in the complex system, that is, the lone pair electrons on the N atom bound to a free proton, undergoing cationization, with the N atom as the charge center.

[0098] Figures 13-14 The HNMR spectra of complexes 2.5[DEA][RA] and 3[DEA][RA] show the same characteristic chemical shift change as that of 2[DEA][RA]. This indicates that the same intermolecular interaction occurs between retinoic acid and a higher proportion of diethanolamine, forming a stable liquid complex at room temperature.

[0099] 1.4.2 Infrared Spectroscopy (IR)

[0100] IR identification of retinoic acid, diethanolamine, and the prepared 2[DEA][RA] was performed (e.g.) Figure 4 As shown in the figure, the results show that: compared with diethanolamine, the peak shift of diethanolamine in 2[DEA][RA] is not obvious; compared with retinoic acid, the characteristic frequency of the C=O double bond of retinoic acid in 2[DEA][RA] (1681.57cm-1) shifts to a lower wavenumber; indicating that there is an interaction between retinoic acid and diethanolamine molecules.

[0101] Complexes with different ratios of RA:DEA were prepared at molar ratios of 1:2, 1:2.5, 1:3, and 1:4; the infrared spectra of the complexes with different ratios were consistent (e.g., Figure 5 As shown in the figure, the characteristic frequency of the C=O double bond (1682 cm-1) shifts to a lower wavenumber, indicating that there is an interaction between retinoic acid and diethanolamine molecules.

[0102] 1.4.3 Raman Spectroscopy

[0103] Raman spectroscopy was used to identify retinoic acid, diethanolamine, and the prepared 2[DEA][RA] (e.g. Figure 6 As shown in the figure, the results show that the Raman spectrum of 2[DEA][RA] is significantly different from that of diethanolamine, and also different from that of retinoic acid. The characteristic frequency of the C=C double bond is 1574.72 cm⁻¹. -1 It moved to a higher wavenumber, reaching 1589.19cm. -1 This indicates that retinoic acid interacts with diethanolamine.

[0104] Example 2: Preparation of retinoic acid triethanolamine complex

[0105] Referring to the preparation process in Example 1, section 1.2, diethanolamine was replaced with triethanolamine, and complexes were prepared using different ratios of retinoic acid and triethanolamine (as shown in the table below). The results showed that retinoic acid and triethanolamine formed complexes at molar ratios of 1:8, 1:9, and 1:10, while at molar ratios of 1:(1–7), it was difficult to form a complex in liquid form at room temperature (see [reference]). Figure 15 ).

[0106] Table B-1 Retinoic acid triethanolamine complexes with different ligand ratios

[0107]

[0108] Example 3: Study on the general physicochemical properties of retinoic acid alcohol amine complexes

[0109] The following physicochemical properties were studied for 2[DEA][RA] prepared according to 1.2.1:

[0110] 3.1 Moisture and Residual Solvents

[0111] The moisture content of three batches of 2[DEA][RA] was tested using a Karl Fischer moisture analyzer. The results showed that moisture and residual solvent in the prepared complex were easily removed.

[0112] Table C-1 Water content of retinoic acid complex

[0113] Complex batch Batch 1 Batch 2 Batch 3 Moisture 0.38％ 0.44％ 0.41％

[0114] 3.2 Dynamic Moisture Absorption (DVS)

[0115] DVS results show (see...) Figure 7 )2[DEA][RA] has a certain degree of hygroscopicity. PLM results (see...) Figure 8 The results showed that there were no crystal particles in 2[DEA][RA] before and after DVS, indicating that the complex has a low risk of retinoic acid precipitation in ambient humidity and can stably maintain its liquid form.

[0116] 3.3 Differential Scanning Calorimetry (DSC)

[0117] DSC results (see) Figure 9 The results show that [DEA][RA] exhibits no exothermic or endothermic signal within the temperature range of -25℃ to 40℃, indicating that the composite has no freezing point within this temperature range. (See mDSC results). Figure 10The results showed that no glass transition temperature of the composite was observed in the range of -25℃ to 25℃. This indicates that the composite can maintain a stable liquid state within this temperature range without the risk of solidification and precipitation.

[0118] Example 4: Water solubility / water dilution resistance of retinoic acid complex

[0119] 4.1 Experimental Objective

[0120] The 2020 edition of the Chinese Pharmacopoeia, Part II, under the entry for retinoic acid, states that retinoic acid is extremely poorly soluble in water. Literature review indicates that the water solubility of retinoic acid is only 1.06 × 10⁻⁶. -6 mol / L (Ascenso A, Guedes R, Bernardino R, et al. Complexation and full characterization of the tretinoin and dimethyl-β-cyclodextrin complex. AAPS PharmSciTech. 2011; 12(2):553-563. doi:10.1208 / s12249-011-9612-3). The poor solubility of retinoic acid poses a great challenge to the formulation process. However, retinoic acid complexes have a certain degree of water solubility, which is beneficial to the preparation of formulations.

[0121] 4.2 Experimental Procedure

[0122] Accurately weigh 2[DEA][RA] with water in different proportions, vortex mix, and observe the properties of the complex with different water contents; after the water content exceeds 90%, use a microsyringe to continue adding water in small amounts multiple times and vortex mix until the solution becomes turbid, weigh and calculate the limiting water content of the complex.

[0123] 4.3 Results and Discussion

[0124] like Figure 11 As shown, 2[DEA][RA] is miscible with water within a water content range of 0–91.4% (w / w) (the liquid in bottles with a water content ≤90% is clear and transparent). When the water content is too high (>91.4%), the hydrogen bonds in the water destroy the complex system, and retinoic acid solid precipitates out (the bottle with a water content of 91.4% is cloudy). The water dilution resistance of the complex with other molar ratios was tested, and the experimental results are shown in the table below. With the increase of the DEA ratio, the water dilution resistance of the retinoic acid diethanolamine complex increases.

[0125] Table D-1 Resistance to water dilution of retinoic acid diethanolamine complexes with different proportions

[0126] [RA]: [DEA] 1:2 1:2.5 1:3 1:4 Maximum moisture content 91.4％ 92.5％ 93.7％ 94.1％

[0127] Example 5: Induced crystallization test of retinoic acid complex

[0128] 5.1 Experimental Objective

[0129] In the practice of chemical synthesis, compounds often form amorphous crystalline states or supercooled liquids during recrystallization, exhibiting a glassy or clear oily appearance. This is similar to the properties of the complex described in this invention. However, this state is unstable and will transform into its stable crystalline state under changing external conditions or seed crystal guidance. Therefore, to rule out this possibility and further demonstrate that the complex prepared in this invention has a stable liquid state, a series of induced challenge experiments will be conducted. Various methods to promote crystallization, such as volatilization tests, stirring tests, and cooling tests, will be used to obtain the solid form of the complex. If a solid form cannot be obtained, the liquid form of the obtained complex can be considered its stable state.

[0130] 5.2 Volatilization Test

[0131] The study investigated whether a solid substance was formed after complete solvent evaporation of the composite in different solvent systems, with and without the polymer, and at different temperatures. The polymer was added to introduce "crystal nuclei" into the system to compare the effect of their presence or absence; different temperatures affected the solvent evaporation rate and the crystallization behavior of the substance.

[0132] Approximately 80 mg of 2[DEA][RA] was dissolved in the appropriate solvent to obtain a clear solution. The clear solution was divided into 4 equal portions. Among them, using the polymer as the "crystal nucleus", the sample was placed at 5℃ and 50℃ for about 4 days without the addition of polymer, or with the addition of polymer B or polymer C. The state of the sample was observed. Except for the added polymer, no solid substances were observed. The results are shown in the table below.

[0133] Table E-1 Results of the Volatilization Test

[0134]

[0135] Polymer B: A mixture composed of five polymers in equal mass ratios: PCL (polycaprolactone), PEG (polyethylene glycol), PMMA (polymethyl methacrylate), SA (octadecyl acrylate), and HEC (hydroxyethyl cellulose).

[0136] Polymer C: A mixture composed of four polymers in equal mass ratios: polystyrene, polytetrafluoroethylene, polytribromostyrene, and polyvinyl stearate.

[0137] 5.3 Stirring Test

[0138] At room temperature (~22℃), 0.3 mL of the corresponding solvent was added to approximately 20 mg of 2[DEA][RA]. After stirring for 3 days at the corresponding temperature, a clear solution was obtained or oil formation was observed. No solid substance was obtained. The results are shown in the table below:

[0139] Table E-2 Results of the stirring test

[0140]

[0141] 5.4 Cooling Test

[0142] Approximately 40 mg of 2[DEA][RA] was dissolved in the appropriate solvent at 50 °C. The resulting clear solution was divided into two equal portions, cooled according to the appropriate procedure, and equilibrated at low temperature for 3 days. No solid form of the substance was obtained in either case. The results are shown in the table below:

[0143] Table E-3 Cooling Test Results

[0144]

[0145]

[0146] 50℃→5℃: The resulting clear solution was equilibrated at 50℃ for 30 minutes, then cooled to 5℃ after 450 minutes, and equilibrated at 5℃ for 3 days.

[0147] 50℃→-20℃: Quickly transfer the clear solution obtained at 50℃ to -20℃ and equilibrate at -20℃ for 3 days. *: Melt immediately after removal.

[0148] 5.5 Liquid nitrogen freezing test

[0149] Approximately 50 mg of 2[DEA][RA] was scooped out with a weighing spoon, and the spoon, along with the sample, was placed into liquid nitrogen (before freezing, it was a reddish-brown transparent liquid). After freezing for about 1 minute, it was removed, yielding a reddish-brown transparent solid (hard and brittle). However, upon rewarming (room temperature: ~22℃), the sample immediately melted (returning to a reddish-brown transparent liquid), and no solid matter was observed. The experimental procedure is as follows. Figure 12 As shown.

[0150] 5.6 Antisolvent Addition Test

[0151] Add the appropriate volume of the positive solvent to an appropriate amount of 2[DEA][RA] to obtain a clear solution. If there are two corresponding antisolvents, divide the clear solution into two portions. At room temperature (~22℃), slowly add the antisolvent to the clear solution while stirring until a solid precipitates (maximum antisolvent addition volume is 1.5 mL). If a solid precipitates, stop adding the antisolvent. Stir at room temperature for about 4 days to obtain a clear solution or observe oil formation. No solid substances were obtained. The results are shown in the table below.

[0152] Table E-4 Antisolvent Addition Test

[0153]

[0154] 5.7 Summary of Induced Crystallization Experiments

[0155] Starting with the retinoic acid diethanolamine complex, a total of 49 induced crystallization experiments were conducted (including evaporation, stirring, cooling and antisolvent addition, and liquid nitrogen freezing). The reaction solvents covered various types of single or binary solvent combinations, and the reaction temperatures ranged from -20℃ to 50℃ (the liquid nitrogen freezing experiment temperature was -196℃). No solid form was obtained in any of the experiments. The results indicate that the retinoic acid diethanolamine complex is difficult to exist in a solid form; that is, the liquid form is its stable state at room temperature.

[0156] Example 6: Investigation of the penetration-enhancing effect of the retinoic acid complex

[0157] 6.1 Comparison of the penetration-enhancing effects of different concentrations of retinoic acid diethanolamine complex

[0158] 2[DEA][RA] was mixed with different amounts of water to prepare complex solutions containing 10%, 20%, and 40% (w / w), respectively. The skin penetration effect of retinoic acid was studied by in vitro transdermal experiments. The results showed that the skin penetration effect increased with the increase of water content.

[0159] Table F-1: Transdermal Comparison of Different Concentrations of 2[DEA][RA]

[0160]

[0161] 6.2 Complex transdermal test

[0162] 6.2.1 Preparation of the complex solution

[0163] A certain amount of complex 2 [DEA][RA] was weighed and dissolved in purified water (so that the concentration of the complex in the aqueous solution was 10% (w / w)). The solution was stirred until homogeneous and vortexed for 3 minutes to ensure uniform mixing. The concentration of the prepared complex aqueous solution was 5.88% (w / w) based on retinoic acid.

[0164] 6.2.2 Preparation of retinoic acid cream

[0165] Prepare 20g of o / w matrix according to the following formulation process for later use.

[0166]

[0167]

[0168] Process:

[0169] Weigh the aqueous phase material according to the prescription, mix it evenly and set aside; weigh the oil phase material according to the prescription, heat it to 80℃ to melt it and mix it evenly; add the aqueous phase while it is hot, and homogenize it for 2 minutes using a high-speed shear dispersion emulsifier at 20000 rpm to form a light yellow emulsion; cool it to room temperature to obtain the final product.

[0170] 6.2.3 Basic Information on Transdermal Testing

[0171]

[0172] *: Before administration, the skin needs to be placed on the diffusion pool for 1 hour to equilibrate, and the TEWL value should be measured;

[0173] **: When administering the medication, ensure the cream is applied evenly and in full contact with the skin, avoiding air bubbles;

[0174] ***: The actual dosage was obtained by weighing using a balance.

[0175] 6.2.4 Test Procedure:

[0176] (1) Experimental preparation: Prepare the sample and receiving solution in advance; prepare pigskin of appropriate size, preferably skin with fewer pores, and weigh the skin, with a weight difference of less than 0.05g;

[0177] (2) Skin equilibration: Assemble the Franz diffusion cell and carefully fix the skin in place; add the receiving solution, remove air bubbles, and ensure that the receiving solution is in full contact with the lower surface of the skin; after the diffusion instrument temperature reaches the preset temperature, allow the skin to equilibrate for 1 hour; measure the TEWL value, which should be less than 20 g / m². 2 h;

[0178] (3) Test: Administer approximately 0.5 ml of the ointment. The ointment should be applied evenly and made into full contact with the skin. The actual amount administered was obtained by weighing using a balance.

[0179] (4) Sampling: The test ended 6 hours later. The receiving fluid and skin were collected and processed.

[0180] 6.2.5 Sample Preparation

[0181] (1) Receiving liquid:

[0182] After the transdermal test, 1.5 ml of the receiving solution was aspirated; centrifuged at 12000 rpm for 15 min, and the supernatant was analyzed by HPLC.

[0183] (2) Skin extract:

[0184] After the transdermal test, the skin surface sample was removed by wiping with a lint-free paper and rinsed with at least 5 ml of PBS. The skin was carefully removed and placed on filter paper to absorb moisture on both sides. The skin surface was then taped 6 times with adhesive tape to remove the stratum corneum. Finally, the skin surface was carefully wiped with a cotton ball soaked in ethanol.

[0185] After removing the skin edges, the skin was cut into small pieces and placed in a 5ml centrifuge tube. 1ml of methanol was added to fully submerge the skin fragments. The skin was extracted by sonication for 60min. After sonication, 0.8ml of the extract was taken and centrifuged at 12000rpm for 15min. The supernatant was then analyzed by HPLC.

[0186] 6.2.6 Test Results

[0187] (1) Transdermal test HPLC detection results

[0188] Retinoic acid was not detected in the receiving fluid. The amount of retinoic acid retained in the skin was measured, and the results are as follows:

[0189] Retinoic acid skin retention (permeability per unit area μg / cm²) 2 )

[0190] sample 1 2 3 mean RSD% 2[DEA][RA] aqueous solution 27.97 8.85 13.71 16.84 59.01 RA ointment 1.13 0.90 1.25 1.09 16.25

[0191] As shown in the table above, the skin retention of the 2[DEA][RA] aqueous solution group was significantly higher than that of the RA cream group, indicating that 2[DEA][RA] has a significant penetration-enhancing effect.

[0192] (2) Skin staining after transdermal test (after removing the stratum corneum and wiping with ethanol)

[0193] After the transdermal test, the skin surface was cleaned, the stratum corneum was removed with adhesive tape, and ethanol was used to wipe away as much sample residue as possible. The results showed that, compared to the RA cream group, the skin in the 2[DEA][RA] aqueous solution group was significantly stained, exhibiting the characteristic yellow color of retinoic acid. This indicates that 2[DEA][RA] significantly improved the transdermal effect of retinoic acid. It should be noted that the actual concentrations of retinoic acid preparations used (0.025%, 0.05%, 0.1%) are much lower than the concentration of the experimental sample (5.88%), therefore, there is no need to worry about skin staining side effects during actual use. The purpose of selecting a higher concentration sample in this experiment was to meet the HPLC limit of quantitation requirements and to more easily verify the penetration-enhancing effect of 2[DEA][RA].

[0194] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A retinoic acid alcohol amine complex, characterized in that, The complex is in liquid form at room temperature; the complex is composed of retinoic acid and diethanolamine, wherein the molar ratio of retinoic acid to diethanolamine is 1:(2-4).

2. The complex according to claim 1, characterized in that, In the complex, the retinoic acid exists partly or entirely in anionic form, and the diethanolamine or triethanolamine exists partly or entirely in cationic form.

3. The complex according to claim 1, characterized in that, The retinoic acid is expressed as follows [A] - [Form exists:] 。 4. The complex according to claim 3, characterized in that, The molar ratio of retinoic acid to diethanolamine is 1:

2.

5. A method for preparing the complex according to any one of claims 1-4, comprising the following steps: The complex was obtained by reacting retinoic acid and diethanolamine.

6. The preparation method according to claim 5, characterized in that, The reaction reagent is water, an organic solvent, or a mixture of an organic solvent and water, wherein the organic solvent is selected from one or more combinations of ethanol, methanol, and acetone.

7. The preparation method according to claim 6, characterized in that, The reaction solvent is water, ethanol, or a mixture of ethanol and water.

8. The preparation method according to claim 6, characterized in that, The volume ratio of organic solvent to water in the mixed solvent is 5:95 to 95:

5.

9. A composition, characterized in that, The composition contains the retinoic acid alcohol amine complex according to any one of claims 1-4.

10. The use of the retinoic acid alcohol amine complex according to any one of claims 1-4 or the composition according to claim 9 in the preparation of a pharmaceutical formulation for treating skin diseases.

11. The application according to claim 10, characterized in that, The skin diseases mentioned are selected from acne, hyperpigmentation, photoaging, psoriasis, ichthyosis, lichen planus, pityriasis rubra pilaris, and keratosis pilaris.

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