This open-label Phase I study has two parts: a drug-drug interaction part intended to investigate the interaction of Pyramax in the pharmacokinetics of the CYP2D6 probe metoprolol and a re-dosing evaluation part intended to investigate the differences on the changes in liver enzymes induced by Pyramax in a first and in a second treatment course and the effect of the redosing interval on the changes in liver enzymes induced by Pyramax in a first and in a second treatment course.