kinetic

It involves the study of rate of change and the way in which this rate is influenced by the concentration of reactants, products, and other chemical species that may be present, and by factors such as solvents, pressure, and temperature.
Kinetics applies to:
Stability
Incompatibility,
Dissolution,
Absorption,
Distribution
Drug action at molecular level
Elimination processes
DRUG STABILITY
• The resistance of the drug to the various chemical, physical, and microbiological reactions that may change the original properties of the preparations during transport, storage and use.
• Quantitatively it is expressed as shelf life.
Shelf life
? is the time period during which a drug product is expected to remain within the approved specification for use, provided that it is stored under the conditions defined on the container label.
? Expiration date is the date placed on the container label of a drug product designating the time prior to which a batch of the product is expected to remain within the approved shelf-life specification if stored under defined conditions and after which it must not be used.
shelf life is the time required for 10% of the material to disappear; it is the time at which reactant concentration (A) has decreased to 90% of its original concentration (i.e., 0.9 A).