This application describes compositions, methods of treatment, and methods of manufacturing a medicament for reducing injury or damage to cells, tissues or organs during ischemia, reperfusion, or following ischemia or trauma. The methods for reducing damage to a cell, tissue or organ comprise administering an effective amount of a composition including (i) a potassium channel opener or agonist and/or adenosine receptor agonist and (ii) an antiarrhythmic agent. The methods may further include postconditioning the cell, tissue or organ.