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Is the ISA of pindolol beta 2-adrenoceptor selective?
1Clinical Research Department, Sandoz Ltd, Basel, Switzerland.
British Journal of Clinical Pharmacology
|January 1, 1987
Summary
Pindolol, a beta-blocker with intrinsic sympathomimetic activity (ISA), selectively stimulates beta 2-adrenoceptors. This action contributes to its antihypertensive effects without stimulating cardiac beta 1-adrenoceptors.
Area of Science:
- Pharmacology
- Cardiovascular Medicine
Background:
- Pindolol is a beta-adrenoceptor antagonist with intrinsic sympathomimetic activity (ISA).
- ISA implies partial agonist activity, meaning it can both block and stimulate beta-adrenoceptors.
Purpose of the Study:
- To investigate the subtype selectivity of pindolol's beta-adrenoceptor stimulation.
- To elucidate the role of ISA in pindolol's cardiovascular effects.
Main Methods:
- In vitro studies on tissues with varying beta-adrenoceptor subtypes.
- In vivo studies in humans, including intra-arterial infusions and assessment of hemodynamic parameters.
- Comparison with beta-blockers lacking ISA.
Main Results:
- Pindolol demonstrated selective stimulant action on beta 2-adrenoceptors in vitro.
- Arteriodilator effects in humans suggest beta 2-adrenoceptor stimulation.
- Pindolol effectively lowers blood pressure, comparable to non-ISA beta-blockers, suggesting minimal beta 1-adrenoceptor stimulation.
Conclusions:
- Pindolol blocks both beta 1- and beta 2-adrenoceptors.
- Evidence strongly suggests pindolol selectively stimulates beta 2-adrenoceptors.
- This selective beta 2-stimulation contributes to its therapeutic profile.
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