Quantification of Drug Action IV

Disadvantages are:
1. Unavoidable tissue injury during dissection.
2. Loss of physiological regulation of
function in the isolated tissue.
3. The artificial milieu imposed on the
tissue.
Concentration-Effect Curves (B)
As the concentration is raised by a constant
factor, the increment in effect diminishes
steadily and tends asymptotically
towards zero the closer one comes
to the maximally effective concentration.
The concentration at which a maximal
effect occurs cannot be measured
accurately; however, that eliciting a
half-maximal effect (EC50) is readily determined.
It typically corresponds to the
inflection point of the concentration–
response curve in a semilogarithmic
plot (log concentration on abscissa).
Full characterization of a concentration–
effect relationship requires determination
of the EC50, the maximally
possible effect (Emax), and the slope at
the point of inflection.