Editing Beta blocker (section)

=== Intrinsic sympathomimetic activity ===
Also referred to as intrinsic sympathomimetic effect, this term is used particularly with beta blockers that can show both agonism and antagonism at a given beta receptor, depending on the concentration of the agent (beta blocker) and the concentration of the antagonized agent (usually an endogenous compound, such as norepinephrine). See [[partial agonist]] for a more general description.{{citation needed|date=October 2023}}

Some beta blockers (e.g. [[oxprenolol]], [[pindolol]], [[penbutolol]], [[labetalol]] and [[acebutolol]]) exhibit intrinsic sympathomimetic activity (ISA). These agents are capable of exerting low-level [[receptor agonist|agonist]] activity at the β-adrenergic receptor while simultaneously acting as a receptor site [[receptor antagonist|antagonist]]. These agents, therefore, may be useful in individuals exhibiting excessive [[bradycardia]] with sustained beta blocker therapy.{{citation needed|date=October 2023}}

Agents with ISA should not be used for patients with any kind of angina as it can aggravate or after myocardial infarctions. They may also be less effective than other beta blockers in the management of [[Angina pectoris|angina]] and [[tachyarrhythmia]].<ref name="Rossi">{{cite book | editor= Rossi S | title=Australian Medicines Handbook |year=2006 |location=Adelaide |publisher=Australian Medicines Handbook| title-link=Australian Medicines Handbook }}</ref>