The property of a drug that produces partial agonist effect at the receptor similar to the cholinergic stimulation of the sympathetic nervous system.
Intrinsic sympathomimetic activity or ISA is often used to describe the property of certain beta-blockers.
Beta-blockers with ISA are beta-blockers that exert a partial agonism at the adrenergic receptor while simultaneously blocking the endogenous catecholamines from binding to the receptor. Hence, they are less potent than catecholamines and other beta-agonists.
See also: agonism, beta-blocker.