Adrenergic receptors blockade

Gobert, A, Rivet, JM, Cistarelli, L, Melon, C and Millan, MJ (1997) Alpha2-adrenergic receptor blockade markedly potentiates duloxetine- and fluoxetine-induced increases in noradrenaline, dopamine and serotonin levels in the frontal cortex of freely moving rats. J. Neurochem. 69 2616-2619. 

Monoamine oxidase inhibition Serotonin reuptake inhibition Norepinephrine reuptake inhibition Dopamine reuptake inhibition a2-Adrenergic receptor blockade Serotonin-2A receptor blockade Serotonin-2C receptor blockade Serotonin-3 receptor blockade op-Adrenergic receptor blockade Histamine-1 receptor blockade Muscarinic cholinergic receptor blockade... 

Deficiency of adrenal medullary catecholamines appears to give no ill effects, and replacement therapy is therefore not used, but adrenal medullary tumours, phaeochromocytomas, secrete excess catecholamines often causing hypertension with dramatic episodes of headache, palpitations, pallor, sweating and anxiety. This condition is normally treated surgically, but preoperative preparation is mandatory to avoid catastrophic effects of surges of catecholamine release. A combination of alpha- and beta-adrenergic receptor blockade is normally used, with drugs such as phenoxybenzamine or doxazosin as alpha-blockers, and propranolol as a non-selective beta-blocker. 

There are two classes of a-adrenergic receptors, aj and a2. Agents with the greatest affinity for aj blockade are chlorpromazine, thioridazine, and risperidone. There are no known beneficial effects associated with a -adrenergic receptor antagonism. However, aj-adrenergic receptor blockade can lead to hypotension, dizziness, and reflex tachycardia (Table 26.2). a2 Blockade is modest for most agents except for risperidone and clozapine. As with aj receptors, there are no benefits that have yet to be associated with a2 receptor... 

Numerous drug-drug interactions have been reported with the antipsychotic agents. These may be mediated through pharmacodynamic effects. For example, antipsychotics that block aj-adrenergic receptors may potentiate the antihypertensive effects of prazosin, labetalol, and some other antihypertensive agents. Conversely, antipsychotics associated with a2-adrenergic receptor blockade may interfere with the antihypertensive effects of clonidine and methyldopa (Richelson, 1999). 

Antipsychotics block aj-adrenergic receptors, which can result in orthostatic hypotension and dizziness. Administration of epinephrine, which stimulates both a- and P-adrenergic receptors, will result in a paradoxical decrease in blood pressure because of the stimulation of P-adrenergic receptors in the presence of aj-adrenergic receptor blockade. 

Cardiovascular effects. Brief hypotension may occur, as may be expected with a-adrenergic receptor blockade. Tachycardia is also... 

Orthostatic hypotension secondary to a -adrenergic receptor blockade... 

The Tricyclic Antidepressant has five actions blocking the reuptake of serotonin, blocking the reuptake of norepinephrine, blockade of alpha 1 adrenergic receptors, blockade of H1 histamine receptors, and blockade of muscarinic cholinergic receptors. 

Rao GHR, Escolar JG, Zavrol J, White JG. Influence of adrenergic receptor blockade m aspirin-nduced inhibition of plateld fundion. Plateldsl990 1 145-150... 

Class II (acebutolol, esmolol, propranolol. Bradycardia, heart block /i-adrenergic receptor blockade... 

Phenothiazines primariiy biock postsynaptic neurotransmission by binding to dopamine (Di and D2), muscarinic, histamine Hj, and serotonergic 5-HT2 receptors. Phenothiazines also possess peripheral a-adrenergic receptor blockade and quinidine-like cardiac effects. Phenothiazines may also lower the seizure threshold. 

Bristow MR. 2000. /1-adrenergic receptor blockade in chronic heart failure. Circ. 101 558-69... 

Beta-adrenergic receptor blockade and the angiotensin-converting enzyme deletion polymorphism in patients with chronic heart failure. Eur J Heart Fail 6 17-21... 

The p-blocking agents produce ocular hypotensive effects by decreasing the production of aqueous humor by the ciliary body without producing substantial effects on aqueous humor outflow facility. The mechanism by which 8-blockers decrease aqueous humor inflow remains controversial, but it is most frequently attributed to / 2-adrenergic receptor blockade in the ciliary body. 

Although bradycardia, transient asystole, and exacerbation of heart failure have been reported with verapamil, these responses usually have occurred after intravenous administration in patients with disease of the S A node or AV nodal conduction disturbances or in the presence of f) adrenergic receptor blockade. The use of intravenous verapamil with a f) adrenergic receptor antagonist is contraindicated because of the increased propensity for AV block and/or severe depression of... 

Qij Adrenergic antagonists Doxazosin, prazosin Selective a, adrenergic receptor blockade -m- -H-... 

Quinidine also produces a adrenergic receptor blockade and vagal inhibition. Thus, the intravenous use of quinidine is associated with marked hypotension and sinus tachycardia. Quinidine s vagolytic effects tend to inhibit its direct depressant effect on AV nodal conduction, so its effect on the PR interval is variable. Moreover, quinidine s vagolytic effect can increase AV nodal transmission of atrial tachycardias such as atrial flutter (Table 34-1). 

Okada DR, Okada RD, Bonow RO. Beta adrenergic receptor blockade causing severe left ventricular systolic dysfunction during dobutamine stress echocardiography in a patient with no structural heart disease. Echocardiography February 2012 29(2) E39-42. 

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