Adrenergic Receptors Blockers

—Bind to adrenergic receptors, but inhibit or block the

— (nor-epinephrine and epinephrine)——Alpha1 and alpha2 receptors——Beta1 and beta2 receptors—Cause both arterial and venous dilation, reducing peripheral vascular resistance and BP—Used to treat hypertension—Effect on receptors on prostate gland and bladder decreased resistance to—Phentolamine——Quickly reverses the potent vasoconstrictive effects of
——Restores blood flow and prevents tissue necrosis.—Is non-selective linking covalently to both Alpha 1 , postsynaptic and alpha 2, presynaptic receptors the block is irreversible and non-selective .—Actions:
—On CVS by  blocking Alpha receptors phenoxybenzamine prevents vasoconstriction of peripheral blood vessels by cathecolamines it cause decrease peripheral resistance and provokes a reflux tachycardia.—These receptors , when block will result in more norepinephrine release which stimulate Beta receptors on the heart to increase cardiac output.—Beta receptors ( Beta 1, Beta 2, Beta 3 ) stimulate adenylyl
—Actions:
—On CVS:  diminishes cardiac output having both negative inotropic and chronotropic effects, it directly depress SA Node, and AV Node, resulting in bradycardia , cardiac output in Oxygen consumption are decreased by blocking of Beta 1 Receptors. These effects are useful in the treatment of Angina.—Alfuzosin ( UROXATRAL )—Doxazosin ( CARDURA )—Phenoxybenzamine ( REGITINE )—Phentolamine ( TEGITINE )—Prazosine (MINIPRESS )—Tamsulosin ( FLOMAX )—Terazosin ( HYTRIN )—Yohimbine ( YOCON )—Acebutolol (SECTRAL )—Atenolol ( TENORMIN )—Betaxolol ( BETOPTIC-S, KERLONE )—Bisoprolol ( ZEBETA )—Carteolol ( CARTROL )—Carvedilol ( COREG, COREG CR )—Esmolol ( BREVIBLOC )—Labetalol ( TRANDATE )—Metoprolol ( LOPRESSOR, TOPROL-XL )—Nadolol ( CORGARD )—Nebevolol ( BYSTOLIC )—Penbutolol (LEVATOL )—Pindolol ( VISKEN )—Propranolol ( INDERAL LA, INNOPRAN XL )—Timolol ( BETIMOL, ISTALOL, TIMOPTIC )

    stimulation of the sympathetic nervous system (SNS)

 —Sympatholytics inhibit—or LYSE—sympathetic

    neurotransmitters

Classified by the type of adrenergic receptor they block

Alpha-Blockers

    urinary outflow, thus reducing urinary obstruction and relieving effects

    extravasated  vasopressors  such  as  nor -epinephrine or epinephrine.

    cyclase via the coupling protein Gs, which leads to an

    increase in cyclic adenosine monophosphate

    concentration in the cell .

Bronchoconstriction blocking Beta 2, receptor in the lungs of patient cause contraction of bronchial smooth muscle this can precipitate respiratory crisis in patient with COPD

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