After , the rate and extent of drug absorption to the systemic circulation determine the onset, duration and the intensity of drug effect.
MEC
onset of effect
Intensity of effect
Duration of effect
The assumption is that the plasma drug concentration has to exceed the minimum effective concentration (MEC) in order to produce the effect, and the intensity of the effect is correlated with the plasma drug concentration.
Rapid drug absorption results in faster onset of drug effect.
Higher extent of drug absorption (higher bioavailability) results in higher plasma drug concentration, which produces more intense effect. Also, the plasma drug concentration will stay above the MEC for longer time which will result in prolonged duration of effect.
