Safety of binodenoson, a selective adenosine A2A receptor agonist vasodilator pharmacological stress agent, in healthy subjects with mild intermittent asthma.

BACKGROUND The pharmacological stress agents adenosine and dipyridamole are contraindicated in asthma patients because of the risk of adenosine receptor-mediated bronchospasm. Binodenoson, a selective adenosine A(2A) receptor agonist, produces maximal coronary hyperemia during pharmacological stress testing yet has a low affinity for the adenosine A(1), A(2B), and A(3) receptors that are probably responsible for bronchospasm. This study was conducted to assess the safety of binodenoson in 87 healthy young adult volunteers with documented mild, intermittent asthma. METHODS AND RESULTS This study consisted of a dose-escalating, single-blinded phase and a placebo-controlled, double-blinded phase conducted in healthy, young adults with documented mild, intermittent, asthma. In the single-blinded phase, 3 sequential cohorts of 8 subjects received intravenous binodenoson (0.5, 1.0, and 1.5 microg/kg). In the double-blinded phase, commenced after medical review of results from the single-blinded phase, subjects were randomly assigned 2:1 to either binodenoson 1.5 microg/kg (n=41) or placebo (n=22). The primary end point was clinically significant bronchoconstriction, defined as a decrease in forced expiratory volume in 1 second of >/=20% from the preinjection measure. Secondary safety end points were changes from preinjection measure in forced expiratory volume in 1 second, forced vital capacity, and forced expiratory flow during the middle 50% of the forced vital capacity; vital signs; pulse oximetry; and adverse events. Binodenoson caused no clinically significant bronchoconstriction or alterations in pulmonary function parameters and transiently increased heart rate and systolic blood pressure. The most common treatment-emergent adverse events were tachycardia, dizziness, and flushing. CONCLUSIONS Binodenoson was safe, well tolerated, and caused no clinically significant bronchoconstriction or pulmonary responses in a small population of healthy subjects with mild, intermittent asthma.