3 Adrenergic receptor antagonist 31-selective

Clinically used p-adrenergic receptor antagonists ( P-blockers ) are either px-selective (e.g. bisoprolol, metoprolol, atenolol, betaxolol) or non-selective,... 

Non-selective P-adrenergic receptor antagonists (e.g. propranolol) can suppress tachycardia and tremor in patients with hyperthyroidism or tremor caused by... 

The major circulating hormones that influence vascular smooth muscle tone are the catecholamines epinephrine and norepinephrine. These hormones are released from the adrenal medulla in response to sympathetic nervous stimulation. In humans, 80% of catecholamine secretion is epinephrine and 20% is norepinephrine. Stimulation of cy-adrenergic receptors causes vasoconstriction. The selective a,-adrenergic receptor antagonist, prazosin, is effective in management of hypertension because it causes arterial and venous smooth muscle to relax. 

The answer is i. (Hardman, p 2312) Timolol is a p-adrenergic receptor antagonist that does not show selectivity for pi or p2 adrenoceptors ... 

Esmolol hydrochloride is a competitive p-adrenergic receptor antagonist it is selective for pT adrenoceptors. In contrast to pindolol, esmolol has little intrinsic sympathomimetic activity, and it differs from propranolol in that it lacks membrane stabilizing activity Of all of the p-adrenergic blocking drugs, this compound has the shortest duration of action because it is an ester, it is hydrolyzed rapidly by plasma esterases and must be used by the intravenous route Esmolol is approved only for the treatment of supraventricular arrhythmias... 

Montorsi, M., Menziani, M.C., Cocchi, M., Fanelli, F. and De Benedetti, P.G. (1998) Computer modeling of size and shape descriptors of al-adrenergic receptor antagonists and quantitative structure-affinity / selectivity relationships. Methods, 14, 239-254. 

Prazosin Is a selective tti-adrenergic receptor antagonist that, at therapeutic doses, has little activity at a2-adrenergic receptors and clinically insignificant direct vasodilating activity. The drug does not cause the other effects attributed to phentolamine. Most important, it produces less tachycardia than does phentolamine and, therefore, is useful in the treatment of essential hypertension. 

Nebivolol is a selective pi adrenergic receptor antagonist with nitric oxide-mediated vasodilatory properties. Nebivolol modulates amyloid-p protein precursor processing in vitro and in vivo. Nebivolol is brain bioavailable and can be readily detected in the brain following 3 weeks of treatment at a dose of 1 mg/kg/day. Chronic nebivolol treatment of Tg2576 mice with amyloid neuropathology reduced brain amyloid content but failed to improve cognitive function [528],... 

Nicardipine has antianginal properties similar to those of nifedipine and may have selectivity for coronary vessels. Isradipine also produces the typical peripheral vasodilation seen with other dihydropyridines, but because of its inhibitory effect on the sinoatrial (SA) node, little or no rise in heart rate is seen. This inhibitory effect does not extend to the cardiac myocytes, however, because no cardiodepres-sant effect is seen. Despite the negative chronotropic effect, isradipine appears to have little effect on the atrioventri-cnlar (AV) node, so it may be used in patients with AV block or combined with a P-adrenergic-receptor antagonist. 

Acebutolol (SECTRAL, Others) is a selective (3j adrenergic receptor antagonist. The drug undergoes significant first-pass metabolism to an active metabolite, diacetolol, which accounts for most of the drug s activity. The elimination t 2 of acebutolol is 3 hours, that of diacetolol, 8—12 hours. 

Propranolol often is effective in relatively low doses (20-80 mg/day). Selective adrenergic receptor antagonists are less effective. 

Task forces from the ACC and the AHA have published guidelines that are useful in the selection of appropriate initial therapy for patients with chronic stable angina pectoris (www.americanheart.org). Patients with coronary artery disease should be treated with aspirin and a P adrenergic receptor antagonist (particularly if there is a history of prior MI). The guidelines also... 

Catechol (22) was treated with 2-chloroacrylonitrile in basic conditions Michael addition to one OH group followed by a Williamson s reaction onto the other gave the nitrile (23) which was elaborated on to idazoxan (24) Scheme 5.7.) [14, 15]. It is claimed to be one of the most potent and selective a2-adrenergic receptor antagonists [16-19], Idazoxan shows unusual differential binding to a2-adrenoreceptors of different species [20]... 

The compound yohimbine and prescription drug yohimbine hydrochloride are selective Oj-adrenergic receptor antagonists and produce dose-dependent increases in blood pressure with no effects on heart rate (Tam et al. 2001). 

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