This phase 3 trial shows that regadenoson provides diagnostic information comparable to a standard adenosine infusion. There were no serious drug-related side effects, and regadenoson was better tolerated than adenosine.

The results of this study demonstrate the utility of regadenoson as a coronary vasodilator for myocardial perfusion imaging.

Regadenoson is well-tolerated and seems as effective as adenosine for detecting and quantifying the extent of hypoperfusion observed with SPECT perfusion imaging. Phase III clinical trials are now underway, given the promise of regadenoson's reduced side effects and simplicity of bolus administration.

There is no effective treatment for cocaine addiction despite extensive knowledge of the neurobiology of drug addiction1–4. Here we show that a selective aldehyde dehydrogenase-2 (ALDH-2) inhibitor, ALDH2i, suppresses cocaine self-administration in rats and prevents cocaine- or cue-induced reinstatement in a rat model of cocaine relapse-like behavior. We also identify a molecular mechanism by which ALDH-2 inhibition reduces cocaine-seeking behavior: increases in tetrahydropapaveroline (THP) formation due to inhibition of ALDH-2 decrease cocaine-stimulated dopamine production and release in vitro and in vivo. Cocaine increases extracellular dopamine concentration, which activates dopamine D2 autoreceptors to stimulate cAMP-dependent protein kinase A (PKA) and protein kinase C (PKC) in primary ventral tegmental area (VTA) neurons. PKA and PKC phosphorylate and activate tyrosine hydroxylase, further increasing dopamine synthesis in a positive-feedback loop. Monoamine oxidase converts dopamine to 3,4-dihydroxyphenylacetaldehyde (DOPAL), a substrate for ALDH-2. Inhibition of ALDH-2 enables DOPAL to condense with dopamine to form THP in VTA neurons. THP selectively inhibits phosphorylated (activated) tyrosine hydroxylase to reduce dopamine production via negative-feedback signaling. Reducing cocaine- and craving-associated increases in dopamine release seems to account for the effectiveness of ALDH2i in suppressing cocaine-seeking behavior. Selective inhibition of ALDH-2 may have therapeutic potential for treating human cocaine addiction and preventing relapse.

Our findings suggest that selective reversible ALDH-2 inhibitors may have therapeutic potential to reduce excessive drinking and to suppress relapse in abstinent alcoholics.