The definition of stability has evolved over time with different meanings by different organizations. For example, the stability in the context of dispensing for pharmacists is defined differently (USP/NF, 1990) from that in the context of pharmaceutical dosage forms for manufacturer. Carstensen (1990) gave the following definition: "The term pharmaceutical stability could imply several
things. First of all, it is applied to chemical stability of a drug substance in a dosage form, and this is the most common interpretation. However, the performance of a drug when given as a tablet . . . depends also on its pharmaceuticas properties (dissolution, hardness, etc.). All of these aspects must, therefore, be a part of the stability program." In the 1987 FDA guideline for the stability of human drugs and biologics (FDA, 1987), stability is defined as "the capacity of a drug product to remain within specifications established to ensure its identity, strength, quality, and purity."