Adrenergic Receptor Antagonists • Excessive sympathetic activity is characteristic of a number of pathological states including: • Hypertension • Angina pectoris • Cardiac arrhythmias • Sympatholytics – adrenergic receptor antagonists • Block , or both • Therapeutic effects due to 1 and 1 blockade • Adverse effects due to 2 and 2 blockade • Therefore 1 and 1 selective antagonists -291, Section 2, Lecture 5
59-291, Section 2, Lecture 5. Adrenergic Receptor Antagonists. Excessive sympathetic activity is characteristic of a number of pathological states including: Hypertension Angina pectoris Cardiac arrhythmias Sympatholytics – adrenergic receptor antagonists Block , or both - PowerPoint PPT Presentation
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Adrenergic Receptor Antagonists• Excessive sympathetic activity is characteristic of
a number of pathological states including:• Hypertension• Angina pectoris • Cardiac arrhythmias
• Sympatholytics – adrenergic receptor antagonists• Block , or both • Therapeutic effects due to 1 and 1 blockade• Adverse effects due to 2 and 2 blockade• Therefore 1 and 1 selective antagonists
59-291, Section 2, Lecture 5
Non-selective -blockers• Block both 1 and 2 receptors
– Ie. phentolamine and phenoxybenzamine Competitive
inhibitor Non-competitive
inhibitor
Chemical sympathectomy
Hypertensive Episodes
- decreases vascular resistance - lowers BP - smooth muscle relaxation in the bladder
Used to treat hypertensive episodes of Pheochromocytoma
– Ie. Alfuzosin, doxazosin, prazosin, terazosin•Used in the treatment of chronic hypertension• Also used to treat urinary retention in men with benign prostatic hyperplasia
Selective 1 blockers cause less reflex tachycardia than phenoxybenzamine and phentolamine
Adverse effect of 1 blockers
• Mostly caused by excessive vasodilation• Hypotension, dizziness, fainting, reflex
tachycardia, palpitation• First-dose syncope: effect on BP when
they are initially administered
-adrenergic receptor antagonists
• Both non-selective and selective -blockers• Non-selective
– ie nadolol, pindolol, propranolol, tomilol– Block both 1 receptors in cardiac tissue and 2 in smooth muscle, liver and other tissues
• Blockade of 1 reduces sympathetic stimulation of heart…
Therefore, negative
• Blockade of 2 may cause broncoconstriction and limit glycogenolysis Adverse effects!!
chronotropeinotropedromotrope
1-antagonist _____
1-antagonists --------
Selective 1-blockers
• Have greater affinity for 1 than for 2 receptors– Ie Acebutolol, atenolol, esmolol, metoprolol
CARDIOSELECTIVE BLOCKERS• Produce fewer adverse effects than non-
selective, but their selectivity is not absoluteIn summary,
-blockers have a number of clinical applications including treatment of:• migraines• Hypertension• angina pectoris• cardiac arrhythmia• glaucoma