Beta agonists selective

Orciprenaline is a partially selective adrenoceptor-agonist and hence it is more likely to have effects on the cardiovascular system, such as arrhythmias, than the selective adrenoceptor-agonists, such as salbutamol, terbutaline and the long-acting beta-agonists salmeterol and formoterol. Orciprenaline is available only as tablets or syrup and can be prescribed to 4-year-old children. 

Fig. 7.25 Design of beta-2 selective adrenoceptor agonists resistant to catechol O-methyl transferase (COMT).

Beta-2-adrenergic agonists, selective fenoterol hydrobromide salbutamol salbutamol sulfate terbutaline sulfate... 

Non-selective beta-agonists (ephedrine, orciprenaline) are now rarely used because of the higher incidence of cardiovascular side-effects by their action on beta-1 receptors... 

NON-SELECTIVE BETA-AGONISTS >- Sympathomimetics section - Cl/S Chapter ... 

Because of its receptor selectivity (the lack of stimulation of the vasodilatory P2 receptor), an agonist that is selective for the receptor tends to cause less reflex tachycardia than a pan-beta agonist. 

Selective alpha agonist, beta agonist Drugs that have relatively greater effects on alpha or beta adrenoceptors none are absolutely selective... 

Beta-adrenergic agonists can be broadly categorized as having beta-1 and beta-2 receptor activity. This section describes the toxicity of several beta-2-selective agonists that are commonly available for oral use albutemi (salbutamol), metapro-terenol, and terbutaline (Table 11-16). 

TABLE 11-16. COMMONLY AVAILABLE BETA-2-SELECTIVE AGONISTS ... 

MIP Technologies, Lund, Sweden Clenbuterol, beta agonists (class-selective), NNAL, riboflavine, triazines (class-selective)... 

Because iCg values for competitive antagonists represent tme dissociation constants, these make possible quantitative interpretations of SARs. Significant use also has been made of iCg values in the quantitative comparison of receptors to determine whether receptors that respond to the same agonists are identical or whether responses produced by different agonists are initiated at the same receptors (44,46). Thus, beta-adrenoceptors in human and guinea pig preparations can be direcdy compared and selective and antagonists quantitated (Table 3). 

Beta receptors of the beta-1 subtype mediate an increase in heart rate and increased force of contraction they are also found in the central nervous system. E and NE are equaHy potent agonists and selective antagonists are atenolol [29122-68-7] and betaxolol [63659-18-7]. Beta-2 receptors are weH known for their involvement in relaxing bronchioles. E is a more potent agonist than NE procaterol [72332-33-3] is a selective agonist ICl 118551 and a-methylpropranolol are selective antagonists. A particular amine may act on both alpha and beta receptors or predominandy on one type. NE acts mainly on alpha-1, E on both alpha and beta, and isoprotemol [7683-59-2] almost exclusively on beta receptors. Numerous antagonists also differentiate between... 

Kenakin, T. P., and Beek, D. (1980). Is prenalterol (H 133/80) really a selective beta-1 adrenoceptor agonist Tissue selectivity resulting selective beta-1 adrenoceptor agonist Tissue selectivity resulting from difference in stimulus-response relationships. J. Pharmacol. Exp. Ther. 213 406—413. 

Agonist-induced conformational changes at the cytoplasmic side of TM6 in the beta 2 adrenergic receptor mapped by site-selective fluorescent labeling. J. Biol. Chem. 276,9279-9290. 

Voss, H.P., Shukrula, S., Wu, T.S., Donnell, D., and Bast, A., A functional beta-2 adrenoceptor-mediated chronotropic response in isolated guinea pig heart tissue selectivity of the potent beta-2 adrenoceptor agonist TA 2005, /. Pharmacol. Exp. Ther., 271, 386-389, 1994. 

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