09 HIGH ON LIFE

In the following image , the effect of drug added via intravenous drug administration is shown by adding a known amount of the drug into the beaker and the graph besides shows the time course of the amount of drug in the beaker.  (CR : Basic and Clinical Pharmacology, Katzung, Lange, 12th Edition)  Example (A):  no movement of drug out of the beaker -->  a steep rise to maximum followed by a plateau.  Example (B): a route of elimination is present --> a slow decay after a sharp rise to a maximum; level of material in the beaker falls --> “pressure” driving the elimination process also falls --> slope of the curve decreases : Exponential decay curve.  Example (C) : drug placed in first "blood" compartment - equilibrates rapidly with second "extravascular" compartment -->  amount of drug in “blood” declines exponentially to a new steady state.  Example (D): model for a more realistic combination of elimination mechanism and extravascular equilibration -

  When we take a drug it gets absorbed into the blood streams and gets distributed into different organs,tissues,sometimes it crosses the blood brain barrier and reaches our grey matter, part of drug also gets eliminated, here blood acts as the central compartment ,sometimes when we take a oral drug some part of it gets lost in its way before it reaches our blood stream due to first pass mechanism in case of IV 100% of the drug gets absorbed in our blood streams Drug distribution or absorption within our body is a very complex process after it comes into our blood it distributes through different tissues, lungs ,intestine,kidney brain in different rates so for further calculating to generate the exact data and the rate kinetics of any drug a hypothetical model is developed by our scientist which is a pharmacokinetic model. There are two types:- compartment modelling  One compartment model  Two compartment model non-compartment modelling(model independent approach) WHY STUDY PHARMACOKIN