MULTICOMPARMENT MODELS
In this when a drug is administered inside the body the entire body cannot act on the drug as a whole single compartment because of the nature of some drugs which distributes into the body in different rates.
The drug distributes more rapidly in the tissues of high blood flow than the tissue area with low blood flow.Drug concentration in various tissues depends on the physical and chemical characters of the drug and the nature of the tissues.
Highly lipid soluble drugs accumulates in fatty tissues.
Two Compartment Models (I.V.Bolus Inj.)
When a drug is given through I.V.Bolus Injection the drug get rapidly distributed in highly perfused tissues (central compartment) and more slowly into peripheral tissues(tissue compartment)
The initial rapid decline in the plasma concentration is due to distribution into the tissues(distrbution phase) followed by the slower rate of decline after the distribution reaches the equillibrium is known as the elimination phase.
The apparent volume of distribution depends on the type of drug kinetics calculations
Volume of distribution is the some of volume of distribution in the central compartment(Vp),the volume of distribution at steady state(Vss),and the volume of distribution at the tissue compartment(Vt)
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