ABSTRACT
A dosage form can be treated as a system delivering a drug to an organism. Two parameters are connected with the term delivery: the total amount of drug delivered to the organism and the rate of delivery, i.e., amount of substance delivered over a unit of time. The process opposite to delivery is drug elimination from the organism. It is comprised of drug metabolism and excretion. The rate of these two processes, as well as physiological and biochemical conditions, determine the length of time that the drug level in the circulation is sufficient to obtain a specific pharmacological action. A dosage form which, due to its special technological construction, provides for drug release having kinetics of zero order in an amount sufficient to maintain the therapeutic drug level over extended time. Chemical substances with various physical and chemical properties applied during the preparation of a dosage form.
