Difference between purified water and water for injection

The difference between purified water and water for injection is also in the water preparation process There are various options for the preparation process of purified water, but each country's pharmacopoeia has limited conditions for the injection process of water for injection For example, the United States Pharmacopoeia clearly stipulates that the preparation process of water for injection can only be distillation and reverse osmosis, while the Chinese Pharmacopoeia stipulates that the production process of water for injection must be distillation These are the necessary conditions for each country to ensure the quality of WFI according to its actual situation At present, many people equate WFI with purified water, which is actually misleading Purified water can be obtained by ion exchange, reverse osmosis, EDI, ultrafiltration and other treatment The purity is also very high, but there is still a gap compared with water for injection The main achievements of purified water used in medical treatment are cleaning of medical devices, production of chemicals, testing water, etc In China, purified water as the source water of WFI, we can see the difference between them Purified water: the electrolyte in the water is almost completely removed, and the insoluble colloidal substances and microbial particles, dissolved gases, organic matters, etc in the water have also been removed to a very low level Purified water is the water for medicinal use prepared by raw water distillation, ion exchange, reverse osmosis or other appropriate methods that meet the drinking water standard, and does not contain any additional agent It can be used as solvent or test water for preparation of common drugs, but not for injection Generally, the residual salt content in pure water should be controlled below 0.1mg/l, and its conductivity should be 0.1us/cm when the water temperature is 25 ℃ Water for injection: the purity of water is similar to purified water The main difference between purified water and purified water is that the water does not contain microorganisms and pyrogens, which is obtained by distillation of purified water It is required to monitor each preparation link at any time and clean the preparation and delivery equipment of sterile injection water regularly Generally, it shall be stored at 80 ℃ or above, kept in heat preservation cycle at 65 ℃ or sterile state at 4 ℃ or below, and used within 12 hours of preparation According to the Chinese Pharmacopoeia, water for injection is distilled water from purified water; it should meet the requirements of bacterial pyrogen test; water for injection must be produced, stored and distributed under the condition of preventing the generation of pyrogen There are two methods to prepare water for injection in USP, distillation and reverse osmosis Water for injection can be used as a solvent or diluent for the preparation of sterile preparations such as injection, eyedrop, etc.; cleaning of containers for injection Sterile water for injection refers to the water for injection prepared according to the injection production process It is the water produced by sterilization of water for injection, sterile and pyrogen free water It can be considered as a preparation The principles for the selection of preparation methods of pharmaceutical water the pharmaceutical water system must effectively deal with and control the pollution of microorganism and bacterial endotoxin, in addition to the control of chemical indicators and particle pollution Reverse osmosis can be used for purified water system, while distillation is more used for injection water system Distilled water machine is often the main water point in the distribution and circulation loop (water loop) of purified water system The USP has great flexibility in the selection of pharmaceutical water source According to its regulations, water for injection can be produced by distillation or reverse osmosis of drinking water, which does not require enterprises to prepare water for injection with purified water as the source water Of course, drinking water standards in the United States are not the same as those in China Experts believe that this flexibility of USP endows the "clause" with wide applicability From its discussion of pharmaceutical water system, its control of water quality is not limited to previous projects and indicators, but also extends to the design, construction, verification, operation monitoring and other aspects of the system The distillation method is used in domestic water for injection, which is certainly related to the quality status of domestic reverse osmosis It should be pointed out that different distilled water machines have different requirements for the source water, and different types of distilled water machines, due to the differences in performance, can respectively take purified water, deionized water and deep soft water as the source water to prepare the injection water that meets the standards On the other hand, the preparation of WFI with drinking water or purified water does not necessarily guarantee that the effluent meets the specified standard, which is related to the performance of the selected equipment It should also be pointed out that the quality of the source water must be monitored and the water intake point should avoid the pollution source as much as possible What is the difference between water for injection and purified water? If the water quality standards of purified water and injection water in USP are compared, the main differences between them can be seen Their physical and chemical indexes are the same, but the requirements of water for injection on pyrogen and microorganism are higher than that of purified water, and the difference is the purity of water What is pyrogen? The specific meaning of heat source is as follows: endotoxin is also called heat source, which is the substance that can cause heat Endotoxin is a component of the cell wall of Gram-negative bacteria, called lipopolysaccharide Lipopolysaccharide is toxic to the host Endotoxin is only released when bacteria die and dissolve or destroy bacterial cells by artificial methods, so it is called endotoxin Endotoxin is not a protein, so it is very heat-resistant Heating at 100 ℃ for 1 hour will not be damaged Only heating at 160 ℃ for 2 to 4 hours, or boiling with strong alkali, strong acid or strong oxidant for 30 minutes can destroy its biological activity There are also differences between endotoxin and exotoxin: endotoxin can not be removed by formaldehyde solution to become toxoid; although a certain amount of specific immune products (called antibody) can be produced by injecting endotoxin into the body, the effect of this antibody on counteracting endotoxin is weak Lipopolysaccharide molecule of endotoxin consists of three parts: cell specific polysaccharide, non-specific core polysaccharide and lipid A Lipid A is the main toxic component of endotoxin The structure of lipid A in different Gram-negative bacteria was similar Therefore, although there are different strains of infection caused by gram-negative bacteria, the toxic effects caused by endotoxin are similar The difference between purified water and water for injection pyrogen and microorganism in USP is listed in the table Microorganism in purified water for injection < 1000cfu / ml 10cfu / 100ml pyrogen does not specify < 0.25eu/ml production method distillation distillation ion exchange reverse osmosis reverse osmosis other appropriate methods purity of water? Usually we use conductivity or resistivity to express its purity Conductivity and resistivity are reciprocal The conductivity of pharmaceutical water (purified water) shall be less than 2 Micro Siemens has no instructions for water for injection per centimeter, but the difference between pharmaceutical water and water for injection lies in the water preparation process There are various choices for the preparation process of purified water However, there are limited conditions for the preparation process of water for injection in Pharmacopoeia of various countries For example, the United States Pharmacopoeia clearly stipulates that the preparation process of water for injection can only be distillation and reverse osmosis, According to Chinese Pharmacopoeia, the production process of WFI must be distillation These are the necessary conditions for each country to ensure the quality of WFI according to its actual situation Water quality standard project for injection water Chinese Pharmacopoeia (2000 EDITION) European Pharmacopoeia (2000 supplement) United States Pharmacopoeia (24th Edition) source this product is the distilled water of purified water, which is the drinking water meeting the legal standards or the purified water distilled by appropriate methods The drinking water meeting the requirements of American Environmental Protection Association, European community or Japan is distilled or reverse osmosis purified, and the properties are colorless, odorless, tasteless, colorless, odorless, tasteless, pH 5.0-7.0, ammonia 0.2ug/ml, chloride, sulfate and calcium salt, nitrite, carbon dioxide, and undeveloped substance meet the requirements Nitrate 0.06ug/ml, 0.2ug/ml Heavy metal 0.5ug/ml 0.1ug/ml aluminum salt