ABSTRACT
In the rational design and evaluation of dosage forms for drugs, the stability of the active
components must be a major criterion in determining their suitability. Several forms of
instability can lead to the rejection of a drug product. First, there may be chemical
degradation of the active drug, leading to a substantial lowering of the quantity of the
therapeutic agent in the dosage form. Many drugs (e.g., digoxin and theophylline) have
narrow therapeutic indices, and they need to be carefully titrated in individual patients so
that serum levels are neither so high that they are potentially toxic nor so low that they are
ineffective. For these drugs, it is of paramount importance that the dosage form
reproducibly delivers the same amount of drug.
