4'-Hydroxycarvedilol is a metabolite of Carvedilol. Incubation of R (+) - and S(-)-carvedilol with rat liver microsomes showed the formation of four oxidative metabolites: 1-hydroxycarvedilol (1-OHC), 8-hydroxycarvedilol (8-OHC), 4'-hydroxycarvedilol (4'-OHC), and O-desmethylcarvedilol (DesC). From in vivo metabolism studies were obtained, that 1-OHC and 8-OHC were the major products for both enantiomers used as a substrate. Also was invented, that 4'-hydroxycarvedilol slightly more effective than carvedilol in suppressing of store overload-induced calcium release (SOICR) through the cardiac ryanodine receptor (RyR2), which can trigger ventricular arrhythmias.