Xamoterol hemifumarate

Xamoterol fumarate is a cardioselective partial beta-agonist, the first of its class to be developed for use in heart failure. The main advantage of xamoterol fumarate as a cardiotonic lies in the fact that its beta-blocking effect exerted during high sympathetic drive will protect the heart from overstimulation. It is claimed to be a viable but safer alternative to digoxin.

Xamoterol is a partial agonist of β₁-adrenergic receptors (β₁-ARs) with an EC₅₀ value of 80 nM for the generation of cyclic AMP (cAMP) in neonatal rat cardiomyocyte cultures. It increases spontaneous contraction of isolated rat right atria (EC₅₀ = 4.67 nM). In vivo, xamoterol increases heart rate in beagle dogs (ED₅₀ = 3.2 μg/kg) and in a rat model of spontaneous heart failure (ED₅₀ = 6 μg/kg), an effect that is reversed by the selective β₁-AR antagonist betaxolol but not the selective β₂-AR antagonist ICI 118551 . Formulations containing xamoterol have been used in the treatment of heart failure.

Crystallizes in ethanol, melting point 168-169℃ (decomposition).

ICI (United Kingdom)

Xamoterol Hemifumarate, is a β1-adrenoceptor-selective partial agonist.

Stimulant (cardiac).

Corwin

β 1 -adrenoceptor-selective partial agonist (pA 2 values are 7.4-7.8 and 5.2-6.2 at β 1 - and β 2 -adrenoceptors respectively).

Store at RT

[1] R N WILLETTE. In vitro and in vivo characterization of intrinsic sympathomimetic activity in normal and heart failure rats.[J]. Journal of Pharmacology and Experimental Therapeutics, 1999, 289 1: 48-53.
[2] M T KOWALSKI. Comparison of the effects of xamoterol and isoprenaline on rat cardiac beta-adrenoceptors: studies of function and regulation.[J]. British Journal of Pharmacology, 1990, 99 1: 27-30. DOI: 10.1111/j.1476-5381.1990.tb14648.x
[3] A. NUTTALL  H. M S. THE CARDIOVASCULAR EFFECTS OF ICI 118,587: A β1-ADRENOCEPTOR PARTIAL AGONIST[J]. British Journal of Pharmacology, 1982, 77 2: 381-388. DOI: 10.1111/j.1476-5381.1982.tb09309.x