The difference between purified water and water for injection

The difference between purified water and water for injection is also in the water production process. The preparation process of purified water can have various options, but the pharmacopoeia of each country has limited conditions for the injection process of water for injection, such as the preparation process of injection water specified by the United States Pharmacopoeia. It can only be distilled and reverse osmosis. The Chinese Pharmacopoeia stipulates that the production process of water for injection must be distillation. These are the necessary conditions for countries to ensure the quality of water for injection according to the actual situation in their country. Many people have used the water for injection and the purified water to equal the number, which is actually a misleading. Purified water can be obtained by treatment with ion exchange, reverse osmosis, EDI, ultrafiltration, and the like. The purity is also very high, but there is still a big gap compared to water for injection. The main achievements in the use of purified water in medical treatment are medical device cleaning, pharmaceutical production, and test water. In China, purified water is used as the source water for water for injection, and the difference between the two can be seen.

Purified water: The electrolyte in water is almost completely removed, and colloidal substances and microbial particles, dissolved gases, organic substances, etc., which are insoluble in water, have also been removed to a very low extent. The purified water is medicinal water prepared by a raw water distillation method, an ion exchange method, a reverse osmosis method or other suitable methods in accordance with drinking water standards, and does not contain any additives. It can be used as a solvent or test water for the preparation of common pharmaceutical preparations, but it should not be used for the preparation of injections. Generally, the remaining salt content in pure water should be controlled below 0.1 mg/L, and when the water temperature is 25 ° C, the conductivity should be 0.1 us/cm.

Water for injection: The purity of water is similar to that of purified water. The main difference from purified water is that the water contains no microorganisms and pyrogens, which is obtained by distillation of purified water. It is required to monitor each preparation step at any time, and regularly clean and disinfect the preparation and delivery equipment for injection water. Generally, it is stored above 80 °C, kept at 65 °C or above, or stored under aseptic conditions below 4 °C, and used within 12 hours of preparation. The Chinese Pharmacopoeia stipulates that water for injection is water obtained by distillation of purified water; it should meet the requirements of bacterial pyrogen test; water for injection must be produced, stored and distributed under the conditions of preventing pyrogen production. There are two methods for preparing water for injection in the United States Pharmacopoeia, namely distillation and reverse osmosis. The water for injection can be used as a solvent or a diluent for sterilizing a preparation such as an injection or an eye drop; and a container for injection. Sterilized water for injection refers to the preparation of water for injection according to the production process of injection. It is water prepared by sterilization of water for injection. It is sterile, pyrogen-free water and can be considered as a preparation.

Principles for the preparation of pharmaceutical water preparation methods In addition to controlling chemical indicators and particulate pollution, pharmaceutical water systems must effectively treat and control microbial and bacterial endotoxin contamination. The purified water system can use reverse osmosis, while the water for injection system uses more distillation. The distilled water machine is often the main water point in the distribution circuit (water circuit) of the purified water system. From the choice of pharmaceutical source water, the United States Pharmacopoeia has greater flexibility. According to its regulations, water for injection can be obtained from drinking water by distillation or reverse osmosis. It is not required for enterprises to use purified water as source water to prepare injections. Use water.

Of course, the drinking water standards in the United States are not the same as those in China. Experts believe that this flexibility of the United States Pharmacopoeia gives wide applicability to the “terms”. From the discussion of the pharmaceutical water system, its control of water quality is not limited to previous projects and indicators, but also extended to System design, construction, verification and operation monitoring. The domestic injection water is distilled, which is of course related to the quality status of domestic reverse osmosis. It should be pointed out that different distilled water machines have different requirements on source water. Different types of distilled water machines can be prepared with purified water, deionized water and deep soft water as source water, respectively, due to differences in performance.

On the other hand, the preparation of water for injection with water that meets drinking water standards or purified water in accordance with standards does not necessarily guarantee that the effluent meets the specified standards, which is related to the performance of the equipment selected. It should also be pointed out that the water quality of the source water must be monitored and the water intake point should be avoided as much as possible.

What is the difference between the quality of water for injection and purified water?

If you compare the water quality standards of purified water in the US Pharmacopoeia with water for injection, you can see the main difference between the two. Their physical and chemical indicators are the same, but the requirements for pyrogens and microorganisms for water for injection are higher than for purified water, and the difference in purity of water.

What is a pyrogen?

The specific heat source is as follows: Endotoxin is also called a heat source, that is, a substance that can cause fever. Endotoxin is a component of the cell wall of Gram-negative bacteria called lipopolysaccharide. Lipopolysaccharides are toxic to the host. Endotoxin is released only when the bacteria die or dissolves the cells by artificial means, so it is called endotoxin. Endotoxin is not a protein and is therefore very heat resistant. Heating at a high temperature of 100 ° C for 1 hour will not be destroyed, only heating at 160 ° C for 2 to 4 hours, or boiling with a strong base, strong acid or strong oxidant for 30 minutes to destroy its biological activity. Unlike exotoxin, endotoxin can not be detoxified by formaldehyde solution to become a toxoid; injection of endotoxin into the body can produce a certain amount of specific immune products (called antibodies), but this antibody counteracts The effect of endotoxin is weak. The endotoxin lipopolysaccharide molecule consists of a bacterial-specific polysaccharide, a non-specific core polysaccharide, and a lipid A. Lipid A is the major toxic component of endotoxin. The lipid A structures of different Gram-negative bacteria are substantially similar. Therefore, the infection caused by Gram-negative bacteria, although the strains are different, the toxic effects caused by endotoxin are roughly the same.

Table listed

Differences between purified water and pyrolysis water and microorganisms in the US Pharmacopoeia

The purity of water? Usually we use conductivity or resistivity to indicate its purity. Conductivity and resistivity are inversely related to each other.

The conductivity of pharmaceutical water (purified water) requires less than 2 microsiemens per cm. The water for injection is not specified, but the difference between the purified water and the water for injection must be based on the water production process and the preparation of purified water. There are various options for the process, but the pharmacopoeia of each country has certain conditions for the preparation 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. The Chinese Pharmacopoeia stipulates that the production process of water for injection must be Distillation. These are the necessary conditions for countries to ensure the quality of water for injection according to the actual situation in their country.

Water quality standard for water for injection

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