There are many factors that affect the effect of the preparation, such as the quality of the original drug, the ingredients of the additives, the processing technology and the dosage form of the preparation, etc. Today we will take the recent hot product pyraclostrobin as an example, from the The impact of the quality of the original drug on the effect of the preparation is analyzed in terms of content, purity, etc., in order to answer users' questions about the different effects of products from different manufacturers.
Pyraclostrobin is a methoxyacrylate fungicide developed by BASF in Germany. It is favored by users for its broad spectrum, high efficiency, safety, health care and increased production. It has developed into the third largest fungicide in the world. The domestic application market has also been extended from cash crops to field crops, and the usage is still growing rapidly.
First of all, let's understand the concept of "crystal". Chemical substances in the dissolved state are affected by various factors during crystallization, and the intramolecular or intermolecular bonding methods will change, resulting in different arrangements of molecules or atoms in the lattice space, forming different crystal structures, which are called crystal forms. Different crystal forms of the same drug may have significant differences in solubility, melting point, dissolution rate, etc., especially for some insoluble drugs, the crystal form has a great impact on the efficacy of the drug.
The content and purity of the original drug have the greatest impact on the effect of the preparation. Different contents of the original drug will have different impurities, which will affect the safety of the preparation. However, the content of pyraclostrobin technical currently available on the market is mostly about 98%, and the content is not much different. Moreover, when the preparation is processed, it is converted and fed according to the percentage. Therefore, the current content of pyraclostrobin technical Effects have less impact.
The impact of the purity of the original drug on the preparation cannot be ignored. It is well known that the products of organic chemical reactions are often multi-component, especially the mixture of isomers. One of the difficulties in the production process of organic chemical pesticides is whether the most active ingredients can be extracted from complex compounds at a higher ratio, that is, to improve the purity of the original drug, which is also directly related to the use effect of the preparation.
According to the patent article of pyraclostrobin crystal form filed by BASF on June 19, 2006, it can be seen that: pyraclostrobin active drug can be divided into amorphous form and crystal form, and the crystalline form of pyraclostrobin is white or light beige Odorless crystal, easily soluble in acetone, ethyl acetate, toluene, dichloromethane, cyclohexanone, acetonitrile, soluble in methanol, ethanol, isopropanol, n-butanol, n-octanol and other organic solvents, slightly soluble in n- Heptane, insoluble in water (1.9mg/L, 20°C). Chinese Patent Publication No. CN101203136B also discloses four crystal forms of pyraclostrobin: Form I, Form II, Form III and Form IV, wherein Form IV is the most stable solid form.
The influence of crystal structure on the effect of pyraclostrobin is firstly because pyraclostrobin active drug is solid, and only solids are involved in the difference of crystal structure; secondly, the bioavailability of pyraclostrobin by different crystal forms The impact of the degree is mostly reflected in the dissolution rate of the active ingredient. Once pyraclostrobin is completely dissolved, the difference in crystal form will no longer exist.
When making suspension dosage form, different crystal forms of pyraclostrobin have different grinding resistance, temperature requirements, and processing difficulty. Once pyraclostrobin is dissolved, for example, it is prepared into an emulsifiable concentrate or other preparations in a completely dissolved state, the influence of the crystal form of pyraclostrobin on the preparation will no longer exist. Therefore, only when pyraclostrobin is used to process the suspension, the purity of pyraclostrobin, that is, the crystal structure problem is involved.
The influence of crystal structure on the effect of pyraclostrobin is also reflected in the difficulty of processing. Because different crystal forms of the original drug have different hardness and melting point, the resistance generated during the grinding process is also different. For example, crystal form I is prepared by melting pyraclostrobin after slow cooling, and the melting point range is 55-56 degrees; crystal form II is pyraclostrobin dissolved in an organic solvent or a mixed solvent, and then volatilized and cooled It is prepared by initiating crystallization method, and its melting point range is 57-58 degrees; crystal form III is obtained by crystallizing pyraclostrobin melt at room temperature, and its melting point range is 59-60 degrees; crystal form IV is pyraclostrobin Strostrobin is dissolved in an organic solvent or a mixed solvent, and then induced to crystallize. The melting point range is 62-72 degrees, and the optimum temperature is 65-67 degrees. Therefore, when processing pyraclostrobin preparations, if different crystal forms of the original drug are selected, there will be a huge difference in the effect between them. Because of this, BASF applied for a crystal form patent 11 years after applying for a compound patent.
This article explains from the aspect of the crystal form of the original drug why there are differences in the effects of the same ingredient content and different manufacturers. Quality is always the life of a product, and only high-quality technical materials can ensure that the preparations can play a full role. It is believed that with the continuous improvement of the quality of pyraclostrobin technical products in the future, overcoming the bottleneck of the purification process will help the preparations to broaden the application range of crops. At the same time, it can also extend the life cycle of the product itself.
