A flurbiprofen ester class of enantiomeric prodrug compounds, methods of making, pharmaceutical compositions, and uses thereof
By developing optically pure enantiomeric prodrug compounds of flurbiprofen esters, the problems of gastrointestinal irritation and inaccurate pharmacokinetics of flurbiprofen have been solved, achieving precise synergistic effects between flurbiprofen and acetaminophen, thus improving the safety and efficacy of the drugs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZUNYI MEDICAL UNIVERSITY
- Filing Date
- 2026-01-30
- Publication Date
- 2026-06-05
AI Technical Summary
The gastrointestinal irritation issues of existing flurbiprofen and the limitations of traditional racemic prodrugs in configuration utilization lead to inaccurate pharmacokinetic and pharmacodynamic studies, affecting efficacy and the complexity of medication administration.
Optically pure flurbiprofen ester enantiomeric prodrug compounds (R)-AF377 and (S)-AF377 were developed, linking flurbiprofen and acetaminophen via ester bonds to achieve optical purity greater than 99.0%, and were separated by chiral preparative chromatography to prepare stable drug compositions.
It significantly improves gastrointestinal safety, achieves precision and efficiency in drug action, solves the problem of non-synergistic release of active ingredients in traditional compound formulations, and has industrialization feasibility.
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Figure CN122145333A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of pharmaceutical chemistry, specifically to a flurbiprofen ester enantiomeric prodrug compound, its preparation method, pharmaceutical composition, and uses. Background Technology
[0002] Nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the most commonly used classes of drugs in clinical practice for treating pain, inflammation, and fever. Flurbiprofen, as a representative drug, exerts its antipyretic, analgesic, and anti-inflammatory effects by inhibiting cyclooxygenase (COX) to block prostaglandin synthesis. However, its long-term safety in clinical use is severely limited by significant gastrointestinal adverse reactions. These adverse reactions mainly include gastric mucosal damage, ulceration, and even bleeding, which stem from two main sources: first, the direct chemical stimulation of the gastric mucosa by the free carboxylic acid groups in the flurbiprofen molecule; and second, its inhibition of COX-1 enzyme, which has a protective effect on the gastrointestinal mucosa, weakening the mucosal defense mechanism. This problem limits the use of flurbiprofen in patients requiring long-term or high-dose treatment.
[0003] To reduce gastrointestinal toxicity, existing technologies mainly employ two strategies: one is to develop selective COX-2 inhibitors (such as celecoxib), but these drugs have been shown to increase the risk of cardiovascular events; the other is to prepare flurbiprofen as an ester prodrug, masking its carboxylic acid group through in vivo hydrolysis to reduce direct stimulation. However, many such prodrugs are still developed based on racemic flurbiprofen (i.e., a mixture of equal amounts of the S- and R-configurations). The S-configuration is the main active form that inhibits COX and exerts anti-inflammatory effects; while the R-configuration, although having a weak inhibitory effect on COX, has been shown to exert analgesic pharmacological effects by influencing the intrinsic pain regulation system. Nevertheless, using the racemic mixture as a starting point for prodrug development fails to fully utilize the advantages of a single active configuration and cannot precisely regulate the potentially different pharmacokinetic and effect characteristics of the two enantiomers, leaving room for optimization in terms of drug design precision and efficiency.
[0004] Furthermore, in clinical analgesia practice, to enhance efficacy, NSAIDs (such as flurbiprofen) are often used in combination with acetaminophen, which has a different mechanism of action. Acetaminophen mainly exerts its analgesic and antipyretic effects through a central mechanism, with a relatively weak anti-inflammatory effect; the combination of the two can achieve complementary effects. However, traditional physical compound preparations have inherent drawbacks: the two independent drug molecules have their own different absorption, distribution, metabolism, and elimination (ADME) characteristics, making it difficult to synchronize their peak blood concentration and duration of action. This prevents precise synergy between the two active ingredients at the target site, thus affecting the optimal therapeutic effect and increasing the frequency and complexity of medication for patients.
[0005] In summary, existing technologies face a multi-faceted challenge: how to address the gastrointestinal irritation of flurbiprofen while overcoming the limitations of traditional racemic prodrugs in configurational utilization, and achieving precise synchronization between flurbiprofen and acetaminophen in pharmacokinetics and pharmacodynamics. Summary of the Invention
[0006] The present invention aims to provide an optically pure flurbiprofen ester enantiomer prodrug compound, which solves the problems of significant side effects, mixed activities, and insufficient bioavailability of existing flurbiprofen combined with acetaminophen or racemic prodrugs; at the same time, it provides an efficient preparation method, a stable pharmaceutical composition and precise therapeutic use of the compound.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: a flurbiprofen ester enantiomeric prodrug compound, wherein the compound is (R)-AF377 as shown in structural formula (I), or (S)-AF377 as shown in structural formula (II); (R)-AF377 is formed by the covalent connection of the carboxyl group of (R)-flurbiprofen and the phenolic hydroxyl group of acetaminophen through an ester bond, and the chiral carbon in the molecule is in the R configuration; (S)-AF377 is formed by the covalent connection of the carboxyl group of (S)-flurbiprofen and the phenolic hydroxyl group of acetaminophen through an ester bond, and the chiral carbon in the molecule is in the S configuration. Equation (I) ((R)-AF377):
[0008] Formula (II) ((S)-AF377): .
[0009] Preferably, as an improvement, it also includes pharmaceutically acceptable salts, solvates, and polymorphs of the (R)-AF377 and (S)-AF377.
[0010] Preferably, as an improvement, the optical purity of both (R)-AF377 and (S)-AF377 is greater than 99.0%.
[0011] A method for preparing the enantiomeric prodrug compound of flurbiprofen ester according to any one of the preceding claims, comprising the following steps: S1. Prepare a solution of racemic flurbiprofen p-acetaminophen ester; S2. Separation was performed using chiral preparative chromatography; S3. Based on the chromatographic retention characteristics of the enantiomers, collect the fractions corresponding to the (R)-AF377 or (S)-AF377 configurations respectively; S4. After solvent removal treatment, optically pure (R)-AF377 or (S)-AF377 solid products are obtained.
[0012] Preferably, as an improvement, the stationary phase of the chiral preparative chromatography in step S2 is silica gel coated with a polysaccharide derivative, and the mobile phase is a mixture of n-hexane and C1-C4 fatty alcohols.
[0013] Preferably, as an improvement, the polysaccharide derivative is amylose-tris(3,5-dimethylphenylcarbamate), the C1-C4 fatty alcohol is isopropanol, and the volume ratio of n-hexane to isopropanol is 82:18-88:12.
[0014] A pharmaceutical composition comprising, as an active ingredient, a flurbiprofen ester enantiomer prodrug compound as described in any one of the preceding claims, the composition comprising a therapeutically effective amount of the active ingredient and at least one pharmaceutically acceptable carrier, diluent, or excipient.
[0015] Preferably, as an improvement, the dosage form of the pharmaceutical composition is selected from oral tablets, capsules, granules, orally disintegrating tablets, lyophilized powder for injection, or transdermal patches.
[0016] Use of the flurbiprofen ester enantiomeric prodrug compound according to any of the preceding claims in the preparation of a medicament for the treatment of pain, inflammation or fever.
[0017] The beneficial effects of this invention are: 1. Significantly improved gastrointestinal safety: The prodrug of this invention masks the free carboxyl group of flurbiprofen through ester bonds, which can completely avoid the direct chemical stimulation of flurbiprofen on the gastrointestinal mucosa.
[0018] 2. Significantly improved drug action precision and efficiency: Through the precise separation and utilization of optically pure enantiomers, (S)-AF377 can simultaneously exert the synergistic anti-inflammatory and analgesic effects of flurbiprofen and acetaminophen, while (R)-AF377 can independently achieve a clear analgesic effect, avoiding the activity interference of different configurations in the racemic mixture, and significantly improving the drug's targeting and utilization efficiency.
[0019] 3. Overcoming the synergistic defects of traditional physical compound formulations: The prodrug of this invention is a single molecular entity that relies on the liver-targeted release mechanism to release two active ingredients simultaneously and in equimolar amounts at the liver target site. This overcomes the problem of poor synergy caused by the asynchronous absorption and distribution of flurbiprofen and acetaminophen in traditional physical compound formulations, ensuring the synergistic and stable efficacy of the drugs.
[0020] 4. Feasibility for industrialization: The preparation process of this invention uses chiral preparative chromatography to achieve efficient separation. The process is stable and controllable, and the yield and optical purity of the target product can meet the requirements of large-scale production, providing reliable technical support for subsequent industrialization. Attached Figure Description
[0021] Figure 1The chiral high-performance liquid chromatography (HPLC) chromatogram of racemic AF377 is shown. Figure 2 Here is the chiral high-performance liquid chromatogram of R-AF377; Figure 3 Here is the chiral high-performance liquid chromatogram of S-AF377; Figure 4 The ¹H NMR spectrum of R-AF377 is shown below. Figure 5 The image shows the ¹H NMR spectrum of S-AF377. Figure 6 To assess the stability of R-AF377 and S-AF377 in simulated gastric and intestinal fluids. Figure 7 To assess the stability of R-AF377 and S-AF377 in human liver microsomes Figure 8 Generation of metabolites of R-AF377 and S-AF377 in human liver microsomal incubation system Figure 9 A comparison of swelling inhibition rates among different groups in a carrageenan-induced paw edema experiment in rats; Figure 10 This is a comparison of the writhing inhibition rates of different groups in the mouse acetic acid writhing test. Detailed Implementation
[0022] The following detailed description illustrates the specific implementation method: Example 1: Chiral separation and purification yielded (S)-AF377 and (R)-AF377 AF377 was dissolved in an appropriate amount of ethanol and purified by chiral preparative high-performance liquid chromatography (HPLC). The chromatographic conditions were set as follows: a chiral column of CHIRALPAKAD-H (250 mm × 20 mm, 5 μm) was used; the mobile phase was a mixture of n-hexane and isopropanol with a volume ratio of 85:15; the flow rate was controlled at 20 mL / min; and the detection wavelength was set at 254 nm.
[0023] Based on the analysis of the spectrum ( Figure 1The retention time differences of different configurations in (R)-AF377 were analyzed. The first elution peak was collected and verified against (R)-flurbiprofen reference standard, confirming that the peak corresponds to the target R configuration. The second elution peak was collected and verified against (S)-flurbiprofen reference standard, confirming that the peak corresponds to the target S configuration. The two fractions were combined and concentrated under reduced pressure to remove the solvent, yielding (R)-AF377 and (S)-AF377 white solids. The yield of (R)-AF377, calculated based on the theoretical amount of the R configuration in the racemic mixture, was 88.5%, and the yield of (S)-AF377, calculated based on the theoretical amount of the S configuration in the racemic mixture, was 83.6%.
[0024] The chromatogram of (R)-AF377, determined by chiral high-performance liquid chromatography (detection conditions consistent with the analytical type, chromatographic column CHIRALPAKAD-H, 4.6×250mm), is as follows: Figure 2 As shown, the chromatogram of (S)-AF377 is as follows: Figure 3 As shown, both exhibit a single sharp peak without any other impurity peaks, proving that their optical purity is greater than 99.0%. Furthermore, the ¹H NMR spectrum of the two products was analyzed, and the ¹H NMR spectrum of (R)-AF377 is shown below. Figure 4 As shown, the ¹H NMR spectrum of (S)-AF377 is as follows: Figure 5 As shown, the spectral data are completely consistent with the target structure, confirming the correctness of the product structure.
[0025] Example 2: Stability Experiment of Artificial Gastric Fluid and Artificial Intestinal Fluid Simulated gastric and intestinal fluids were prepared separately, with the simulated gastric and intestinal fluids having a pH of 1.2. (S)-AF377 and (R)-AF377 were added to the two simulated media respectively, with the initial concentration of both compounds controlled at approximately 50 μg / mL. The systems were then incubated in a 37°C constant-temperature water bath with shaking.
[0026] Samples were taken at 0, 1, 2, 4, and 6 hours of incubation. Acetonitrile was added immediately after sampling to terminate the reaction. The supernatant was collected after centrifugation and analyzed by high-performance liquid chromatography (HPLC) to determine the residual content of the two compounds. The results showed that during the 6-hour incubation period, the residual content of (S)-AF377 and (R)-AF377 in simulated gastric and intestinal fluids remained above 95%, with no significant degradation observed. Figure 6 This result confirms that the ester bond between (S)-AF377 and (R)-AF377 is highly stable in the gastrointestinal environment and can pass through the gastrointestinal tract with its intact structure, effectively avoiding mucosal irritation caused by the direct release of flurbiprofen carboxylic acid groups into the stomach.
[0027] Example 3: Liver-targeted release experiment Fresh rat liver microsomal suspensions were prepared as a source of high expression of carboxylesterase 2 in the liver. 10 μM of (S)-AF377 or (R)-AF377 was mixed with liver microsomal incubation solution and co-incubated at 37°C.
[0028] Samples were taken at 0, 5, 10, 20, and 30 minutes of incubation. After sampling, ice-cold acetonitrile was added to precipitate the protein. The supernatant was then centrifuged and analyzed by high-performance liquid chromatography (HPLC). The results showed that within 5 minutes of incubation, the concentrations (molar concentrations) of (S)-AF377 and (R)-AF377 decreased by 51.7% and 57.0%, respectively. Figure 7 After incubation for 10, 20, and 30 minutes, the time-dependent effects of both compounds diminished. Simultaneously, (S)-flurbiprofen (or (R)-flurbiprofen) and acetaminophen showed a time-dependent increase, with their molar ratio approaching 1:1. Figure 7 , 8 This result demonstrates that the prodrug of this invention undergoes rapid and specific hydrolysis only under the action of hepatic microsomal enzymes, achieving simultaneous and quantitative release of the two active ingredients, and verifying the effectiveness of its liver-targeted synergistic release mechanism design.
[0029] Example 4: Carrageenan-induced paw edema experiment in rats Healthy rats were selected and randomly divided into 11 groups, with 6 rats in each group. The groups were: model control group, flurbiprofen group, S-flurbiprofen group, R-flurbiprofen group, acetaminophen group, flurbiprofen + acetaminophen combination drug group, S-flurbiprofen + acetaminophen combination drug group, R-flurbiprofen + acetaminophen combination drug group, AF377 group, S-AF377 group, and R-AF377 group.
[0030] All groups were administered the drug via gavage at a uniform dose of 74.4 μmol / kg. The model control group received an equal volume of physiological saline as a solvent control. One hour after drug administration, 1% carrageenan solution was subcutaneously injected into the right hind paw of each rat to establish an acute inflammation model. The difference in weight between the left and right hind paws was used as the evaluation index for swelling degree, and compared with the model control group. The swelling inhibition rate of each group 3 hours after inflammation induction was calculated using the formula: Swelling inhibition rate = (Average swelling degree of model group - Average swelling degree of drug administration group) / Average swelling degree of model group × 100%.
[0031] Experimental results are as follows Figure 9As shown, the S-AF377 group effectively inhibited carrageenan-induced toe swelling, and its swelling inhibition rate was significantly higher than that of the flurbiprofen group, S-flurbiprofen group, acetaminophen group, and various combination drug groups at the same molar dose. This indicates that the anti-inflammatory activity of S-AF377 is superior to that of racemic flurbiprofen, single-configuration flurbiprofen, R-AF377, racemic AF377, and the combination drug group of flurbiprofen and acetaminophen.
[0032] Example 5: Mouse Acetic Acid Writhing Test KM mice were selected and randomly divided into groups of 10 each: model control group, flurbiprofen group, S-flurbiprofen group, R-flurbiprofen group, acetaminophen group, flurbiprofen + acetaminophen combination drug group, S-flurbiprofen + acetaminophen combination drug group, R-flurbiprofen + acetaminophen combination drug group, AF377 group, S-AF377 group, and R-AF377 group.
[0033] All groups were administered the drug via gavage at a uniform dose of 74.4 μmol / kg. The blank control group received an equal volume of physiological saline via gavage. One hour after drug administration, mice in each group were intraperitoneally injected with 0.6% acetic acid solution at a volume of 0.2 mL per mouse. The number of writhing movements in the mice over 20 minutes was immediately recorded. The analgesic activity of the drug was evaluated using the writhing inhibition rate, calculated as follows: Writhing inhibition rate = (Average number of writhing movements in the blank control group - Average number of writhing movements in the drug-treated group) / Average number of writhing movements in the blank control group × 100%.
[0034] Experimental results are as follows Figure 10 As shown, the writhing inhibition rate of the R-AF377 group was significantly higher than that of other groups with the same molar dose, indicating that R-AF377 has excellent analgesic activity and its analgesic effect is superior to that of acetaminophen, S-AF377, racemic AF377, and the combination of flurbiprofen and acetaminophen.
[0035] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.
Claims
1. A flurbiprofen ester enantiomer prodrug compound, characterized in that: The compound is (R)-AF377 as shown in structural formula (I), or (S)-AF377 as shown in structural formula (II); Equation (I) ((R)-AF377): Formula (II) ((S)-AF377): 。 2. The flurbiprofen ester enantiomer prodrug compound according to claim 1, characterized in that: It also includes pharmaceutically acceptable salts, solvates, and polymorphs of the (R)-AF377 and (S)-AF377.
3. A flurbiprofen ester enantiomer prodrug compound according to claim 1 or 2, characterized in that: The optical purity of both (R)-AF377 and (S)-AF377 is greater than 99.0%.
4. A method for preparing the enantiomeric prodrug compound of flurbiprofen esters according to any one of claims 1-3, characterized in that: Includes the following steps: S1. Prepare a solution of racemic flurbiprofen p-acetaminophen ester; S2. Separation was performed using chiral preparative chromatography; S3. Based on the chromatographic retention characteristics of the enantiomers, collect the fractions corresponding to the (R)-AF377 or (S)-AF377 configurations respectively; S4. After solvent removal treatment, optically pure (R)-AF377 or (S)-AF377 solid products are obtained.
5. The method for preparing flurbiprofen ester enantiomer prodrug compounds according to claim 4, characterized in that: In step S2, the stationary phase of the chiral preparative chromatography is silica gel coated with a polysaccharide derivative, and the mobile phase is a mixture of n-hexane and C1-C4 fatty alcohols.
6. The method for preparing flurbiprofen ester enantiomer prodrug compounds according to claim 5, characterized in that: The polysaccharide derivative is amylose-tris(3,5-dimethylphenylcarbamate), the C1-C4 fatty alcohol is isopropanol, and the volume ratio of n-hexane to isopropanol is 82:18-88:
12.
7. A pharmaceutical composition, characterized in that: The composition uses the enantiomeric prodrug compound of any one of claims 1-4 as the active ingredient, and the composition comprises a therapeutically effective amount of the active ingredient and at least one pharmaceutically acceptable carrier, diluent or excipient.
8. A pharmaceutical composition according to claim 8, characterized in that: The dosage form of the pharmaceutical composition is selected from oral tablets, capsules, granules, orally disintegrating tablets, lyophilized powder for injection, or transdermal patches.
9. Use of the flurbiprofen ester enantiomer prodrug compound according to any one of claims 1-4 in the preparation of a medicament for treating pain, inflammation or fever.