The objective of the study was evaluate that there is no clinically relevant interaction between amitriptyline (or its metabolite nortriptyline) and BIRT 2584 XX (or its metabolite BI 610100) when BIRT 2584 XX is administered as a tablet formulation to near steady state in an estimated high therapeutic dose. Pharmacokinetics (PK) of amitriptyline and nortriptyline were measured before dosing of BIRT 2584 XX, after the first dose of BIRT 2584 XX, and after repeated doses of BIRT 2584 XX near steady state