Drug Flow Diagram

Basic Definitions*

        Pharmacokinetics is the study of the movement of drugs through the human system, from
        their introduction by ingestion, injection, or other means, to elimination through excretion or
        metabolism. It makes heavy use of compartment models as found in many differential
        equations textbooks. Since almost all students take medications from time to time,
        pharmacokinetics models are something they can easily relate to. 

        For convenience many drugs are taken orally in the form of tablets. With some exceptions,
        these tablets [dosage forms] are designed to swell and disintegrate rapidly [release],
        causing the medication to dissolve quickly in the gastrointestinal tract [dissolution]. From
        there, the medication passes into the bloodstream [absorption], which delivers it to the
        sites at which it has therapeutic effect. Typically, the drug is removed from the bloodstream
        by filtration through the kidneys [excretion] or by metabolism in the liver.

        *The very clear and concise definitions above are from Spitznagel (see CKM Absorption 
           Models, AM Definition 2).