The pH is important in aqueous, drug-product formulation, especially since it involves drug solubility, activity, absorption, stability, sorption and patient comfort. The pH is also related to certain physical characteristics, such as the viscosity of some polymers used as gel-forming agents and in suspensions. The pH is adjusted by using acidifying and alkalizing agents. Acidifying agents are used in a formulation to lower the pH and alkalizing agents are used to increase the pH.
For all the reasons cited above, many times a formulation may already contain one of these agents to achieve a desirable pH. In all cases, before finishing up preparing a formulation that contains water, the pharmacist must check the pH and adjust it, if needed. Generally, because of easy incorporation, freshly prepared solutions of these agents can be used to adjust pH in such formulations.
The USP XXVIII/NF 23 specifically lists 14 acidifying agents and 9 alkalizing agents although other agents can also be used for their pH-altering effect.
| Select an agent by clicking on the name |
|
Acetic Acid, glacial, USP |
Acetic Acid, NF |
Citric Acid, anhhydrous USP |
|
Citric Acid, monohydrate USP |
Fumaric Acid, NF |
Hydrochloric Acid, diluted, NF |
|
Hydrochloric Acid, NF |
Lactic Acid, USP |
Malic Acid, NF |
|
Nitric Acid, NF |
Phosphoric Acid, NF |
Phospohoric Acid, diluted, NF |
|
Propionic Acid, NF |
Sodium phosphate monobasic, NF |
Sulfuric Acid, NF |
|
Tartaric Acid, NF |
| Select an agent by clicking on the name |
|
Ammonia solution, strong, NF |
Ammonium carbonate, NF |
Diethanolamine, NF |
|
Monoethanolamine |
Potassium hydroxide, NF |
Sodium bicarbonate, USP |
|
Sodium borate, NF |
Sodium carbonate, NF |
Sodium hydroxide, NF |
|
Sodium phosphate dibasic, USP |
Trolamine, NF |
