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How does the pH of the release medium affect Carbomer?
Jan 16, 2019

The dissociation constant (pKa) of carbomer is about 6 in the acidic medium. The carbomer base wood is in a non-ionic state, and the degree of swelling is small. The soluble drug molecules can diffuse through the microporous structure of the skeleton, and the drug release is relatively Faster. When the pH is >5, the carbomer molecule is negatively charged, and the degree of ionization of the fumaric acid group in the molecule is higher than that of the human. Due to the hydration of the polymer, the repulsive effect of the adjacent negative electrons of the molecular chain makes the polymer Fully expanded, the gap between the skeletons is reduced, and the release of the drug is slowed down. In most liquid systems, carbomer needs to be neutralized. Sodium hydroxide, potassium hydroxide, hydroxide and some water-soluble organic amines are good neutralizers for carbomer in water. When the pH is >10, the thickening efficiency is lost again, and the excessive neutralizing agent acts as a discrete ion. Therefore, the carbomer's *pH is 5 - l0.