Drug tolerance

Drug tolerance (or physiological tolerance) is a term used to describe that the organism gets used to a given substance. Drug tolerance also means that over time a drug becomes less effective and larger amounts of the substance are needed to get the same effect.  

Physiological tolerance can be achieved in one of the following ways: 
 By changing the number of receptors for a substance 
 By changing the way the signal is handled 
 By changing the receptors themselves 
 By changing the system that antagonizes the receptor 

 References 
Category:Drugs