ABSTRACT
Maintenance of an appropriate pH is important for certain solutions and suspensions. This is because many drug substances are known to have greater solubility or stability at a certain known pH. Moreover, certain preparations are known to cause discomfort at certain pH values. For example, ear preparations cause discomfort when the solution pH is less than 4. The pH is defined as the as the negative logarithm of the hydrogen ion concentration or logarithm of the reciprocal of the hydrogen ion concentration. Since values of hydrogen ion concentration are very small, they are expressed in exponential notation as pH.
