To provide a simple method to keep a solution under a low pH for sterilization and to increase pH before injection without adding any composition.
A method to prepare a liquid product to solve the above problem comprises, a process to prepare a product having at least similar pH of a desired final pH level, a process to decrease pH of the product lower than the desired final level and a process to increase pH of the product toward the desired final pH level over a stated period by releasing carbon dioxide from the product. Preferably, the method includes a process to add a compound to generate carbon dioxide to the product. The method to prepare a medical solution is provided as one implementation including a process to place the solution in a gas-permeable container and a process to let carbon dioxide permeate from the container until the desired pH is obtained.
Takaaki Yasumura
Natsuki Morishita