Why is it necessary to adjust the pH of powder for injection? 1. **Ensuring chemical stability**: Many drugs (such as β-lactam antibiotics and biological products) are prone to degradation reactions such as hydrolysis and oxidation in aqueous solutions. By adjusting the pH to the region where the drug is most stable (usually the trough of the “pH-degradation rate curve”), the degradation can be significantly slowed down, thereby extending the shelf life. 2. **Maintaining physical solubility**: Weakly acidic or basic drugs have different degrees of dissociation at different pH values. An improper pH can cause the drug to crystallize out. If these crystals enter the bloodstream, they may lead to embolism or granulomas, which are serious safety risks associated with medication and constitute severe adverse reactions during infusion. 3. **Reducing injection irritation and tissue damage**: Maintaining an appropriate pH is essential to meet the physiological tolerances of injection administration and to minimize irritation (a mandatory requirement of pharmacopoeias). The normal pH of human blood and tissue fluid is between 7.35 and 7.45. The Chinese Pharmacopoeia has specific regulations regarding the pH range for injections. If the solution is too acidic (pH < 4), it can cause degeneration of the vascular endothelial proteins, leading to pain and phlebitis during intravenous infusion; intramuscular injection may result in redness, swelling, induration, and tissue necrosis. If the solution is too alkaline (pH > 9), it can corrode the vascular endothelium and destroy blood cells, causing hemolysis and vasospasm. Adjusting the pH to match the pH of blood can minimize irritation. 4. **Meeting formulation and clinical compatibility requirements**: The production of powder for injection involves first preparing the drug in a solution and then freeze-drying it. Adjusting the pH during solution preparation ensures the stability of the solution during filling and freeze-drying processes, as well as rapid and clear reconstitution after freeze-drying. Additionally, in clinical use, the solution is often mixed with other fluids. An appropriate pH prevents precipitation or discoloration in common solvents such as saline and glucose injections. 5. **Inhibiting microbial growth and ensuring sterility**: Microorganisms (bacteria and molds) have an optimal pH for proliferation. Most pathogenic bacteria thrive in slightly acidic or alkaline environments. Extreme pH values can disrupt the enzyme systems and cell membrane structures of microorganisms, inhibiting the growth of residual bacteria and aiding in the sterile preservation of the powder for injection. **Jingjing Pharmaceutical’s anhydrous sodium carbonate**: Used as a solubilizer and pH regulator for powder for injection. Jingjing Pharmaceutical’s anhydrous sodium carbonate focuses on delivering value and exceeding customer expectations, offering customized products with precise control of physical properties (such as particle size and bulk density).