Background and overview[1]
Sitagliptin phosphate (1) is a new anti-type 2 diabetes drug. It was developed by Merck & Co. and was approved by the US FDA in October 2006. It is the first drug for the treatment of type 2 diabetes. Dipeptidyl peptidase IV (DPP-4) inhibitor drugs. Sitagliptin phosphate is highly effective in the treatment of type 2 diabetes. As a new type of anti-diabetic drug, sitagliptin phosphate is blood sugar dependent and has moderate hypoglycemic effect. It increases insulin secretion without causing hypoglycemia, effectively reduces hunger, and has the advantages of no nausea, vomiting, edema and increased blood sugar levels. Body weight and other side effects.
Preparation[1]
There are many methods for synthesizing sitagliptin phosphate that have been reported. In summary, there are mainly two synthetic strategies: one is (R) -3-(tert-butoxycarbonylamino) -4-( 2, 4 , 5-trifluorophenyl)butyric acid (8) and 1,2,4-triazolopyrazine (9) are condensed and deprotected to prepare sitagliptin phosphate; the other is diketone compound 2 and 1 , the condensation of 2,4-triazolopyrazine (9), followed by enamination and asymmetric catalytic hydrogenation to prepare sitagliptin phosphate. Recently, Merck reported that the diketone compound (2) and 1,2,4-triazolopyrazine were Sitagliptin phosphate is synthesized in one step from the condensate of azolopyrazine (9) via a biological transaminase reaction.
The above preparation methods have defects such as high raw material costs, complex reaction operations, use of precious metal catalysts, and long reaction times to varying degrees.
Lu Chenglin et al. designed a new synthetic route: using 2,4,5-trifluorophenylacetic acid as raw material, and 2,2-dimethyl-1,3-dioxane-4,6-dione Condensation gives diketone compound 2, 2 is heated and decarboxylated in methanol to give -ketone ester (3), 3 reacts with (S)-phenylglyamide to give chiral enamine (4), 4 via borane/L-diphenyl Asymmetric reduction of prolinol (CBS catalyst) gave a pair of diastereoisomers 5a and 5b. Among them, 5a underwent a 7-step reaction of excision of the chiral auxiliary group, Boc protection of the amino group, and hydrolysis to obtain the key intermediate (R) – 3-(tert-butoxycarbonylamino)-4-(2,4,5-trifluorophenyl)butyric acid (8), 8 is condensed and desorbed with 1,2,4-triazolopyrazine under the action of EDC The target product 1 was obtained by removing the Boc protecting group, with a total yield of 33%. The entire synthetic route is shown in Figure 1.
Quality Control[2]
1 Screening of chromatographic conditions
After consulting the European Pharmacopoeia and the United States Pharmacopoeia, the chromatographic conditions for the content determination of sitagliptin phosphate were obtained: mobile phase acetonitrile-1.36 g/L potassium dihydrogen phosphate-phosphate buffer (phosphoric acid to adjust pH to 2.0) (15:85 ), the flow rate is 1.0 mL/min, the column temperature is 30°C, and the detection wavelength is 205 nm. Considering that the pH of the salt solution of this mobile phase is 2.0 and is peracidic, it may damage the chromatographic column, so it will not be considered. After consulting relevant literature, the chromatographic conditions for determination of sitagliptin phosphate content were: methanol-0.1% perchloric acid (32:68), flow rate 1.0 mL/min, column temperature 30°C, and detection wavelength 268 nm.
The sitagliptin phosphate reference substance was injected and analyzed under the above chromatographic conditions. The retention time of the main peak was about 30 minutes, and the retention time was too long.The ratio of methanol-0.1% perchloric acid and the flow rate were changed several times to adjust the retention time of the main peak, and the effect of column temperature on the chromatographic peak was investigated. At the same time, the sitagliptin phosphate reference substance was measured in the wavelength range of 200~350 nm according to UV spectrophotometry. Scan the entire wavelength to determine its maximum absorption wavelength. The final chromatographic conditions for determination of sitagliptin phosphate content were: mobile phase methanol-0.1% perchloric acid (45:55), flow rate 0.8 mL/min, column pigment carbon black temperature 25°C, and detection wavelength 205nm.
2 Preparation method of test solution
In the test, adjust the ratio of methanol to 0.1% perchloric acid to prepare the test solution, inject samples at 0, 4, 8, 12 and 24 hours according to the above chromatographic conditions, observe the changes in the peak area of the main peak, and examine its stability. It was found that sitagliptin phosphate is relatively stable in any ratio of methanol-0.1% perchloric acid solution, its RSD values are less than 2.0%, and the chromatographic peak shape is good during injection analysis. In order to facilitate the experimental operation, the mobile phase was used as sitagliptin phosphate diluent to dissolve the drug.
3 Selection of dissolution method
According to the European Pharmacopoeia, the dissolution method of sitagliptin phosphate tablets is: rotation speed 50 r/min, dissolution medium 0.01 mol/L HCl (1000 mL), dissolution time 30 minutes. After consulting other relevant information, we found that the dissolution method of sitagliptin phosphate tablets is: rotating basket method, rotation speed 100 r/min, dissolution medium water (900 mL), dissolution time 30 minutes. In order to better examine the dissolution behavior of sitagliptin phosphate under different pH conditions, water, 0.01 mol/L HCl, PBS4.5 and PBS6.8 were used as four dissolution media; taking into account the physiological environment of the human gastrointestinal tract and peristalsis speed, the proposed alcohol speed is 50 r/min. The final dissolution method of sitagliptin phosphate tablets was: slurry method, rotation speed 50 r/min, dissolution medium water, 0.01 mol/L HCl, PBS4.5 and PBS6.8 (1000 mL), dissolution time 60 min.
4 Preparation of dissolution sample solution
In order to make the test operation simple and easy, UV spectrophotometry was used to measure the dissolution of the sample solution. Since when using UV spectrophotometry to measure the absorbance of a sample solution, it is appropriate that the absorbance of the sample solution is between 0.3 and 0.7. In the test, the concentration of the dissolved sample solution was determined to be diluted 5 times so that the absorbance was between 0.3 and 0.7. between.
Main reference materials
[1] Lu Chenglin, Shen Fangliang, Sun Xinzhe, Zhang Xingxian. Synthesis of type 2 diabetes drug sitagliptin phosphate [J]. Chinese Journal of New Drugs, 2014, 23(13): 1574-1578.
[2]Zhang Jinfen, Zhou Yuhong, Li Jibin, Xing Zhengying, Fang Zhizhong. Quality control of sitagliptin phosphate tablets[J]. Journal of Tianjin Medical University, 2018, 24(01):73-77.
[3] Lu Fei, Ouyang Xueyu, Li Ruifeng, Zhao Jingxue, Wei Yongyan. Analysis and early warning of Chinese patent applications involving sitagliptin [J]. Chinese Medical Biotechnology, 2015, 10(03): 280-285 .
