In the field of pharmacology, a selective receptor modulator or SRM is a type of drug that has different effects in different tissues.

[1] A SRM may behave as an agonist in some tissues while as an antagonist in others.

Hence selective receptor modulators are sometimes referred to as tissue selective drugs or mixed agonists / antagonists.

This tissue selective behavior is in contrast to many other drugs that behave either as agonists or antagonists regardless of the tissue in question.

Classes of selective receptor modulators include: