Changes

===Self-antagonism===

===Self-antagonism===

If some drugs are repeadtedly given its effect can decrease. This is called '''tachyphylaxis''' or '''desensitisation'''. If a gradual decrease in response to a drug occurs this is called '''tolerance''' and if the drug loses total therapeutic efficacy it is deemed '''refractory'''. Many types of mechanisms occur to cause this phenomenon, the most important include:

If some drugs are repeatedly given its effect can decrease. This is called '''tachyphylaxis''' or '''desensitisation'''. If a gradual decrease in response to a drug occurs this is called '''tolerance''' and if the drug loses total therapeutic efficacy it is deemed '''refractory'''. Many types of mechanisms occur to cause this phenomenon, the most important include:

* chnage in receptor type

* change in receptor type

* loss of receptors

* loss of receptors

* exhaustion of cell mediators

* exhaustion of cell mediators