Xamoterol. A preliminary review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use.

Xamoterol is a partial agonist at the beta 1-adrenoceptor. Haemodynamic studies indicate that xamoterol moderately increases myocardial contractility, improves diastolic relaxation and lowers left ventricular filling pressure at rest and during moderate exercise. At higher levels of sympathetic activity (e.g. strenuous exercise) it produces negative chronotropic responses whilst the reduced filling pressure is maintained. Studies in patients with mild to moderate chronic heart failure demonstrate an advantage for xamoterol 200mg twice daily over placebo and digoxin with respect to improvement in exercise capacity and symptoms. In limited trials to date the initial response seems to be maintained during periods of up to 12 months. Preliminary small studies suggest that xamoterol is useful in the treatment of some patients with angina pectoris, sinoatrial disease or postural hypotension, although further studies are needed to confirm its clinical role in such patients. Xamoterol appears to be generally well tolerated, but deleterious effects in a small number of patients with asthma, or severe heart failure due to dilated cardiomyopathy indicate the need for cautious use of xamoterol in patients with these diseases. Thus, xamoterol is a promising addition to the drugs available to the physician for treating patients with mild to moderate heart failure although further controlled studies are required to clearly establish its precise role.