The secondary objectives are (1) to evaluate the single dose pharmacokinetics of BI 661051, (2) to explore dose proportionality, (3) to explore the relative bioavailability when BI 661051 is administered as tablet at two dose levels compared to oral drinking solution and (4) to assess the effect on the bioavailability when BI 661051 is administered as oral drinking solution after intake of a high fat meal.