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

Inclusion Criteria:

• Healthy female or male volunteers as determined by the results of screening based upon a complete medical history, including physical examination, measurement of vital signs (Blood Pressure (BP), Pulse Rate (PR)), 12-lead ECG, and clinical laboratory tests
• Age ≥ 18 and ≤ 55 years
• BMI ≥ 18.5 and ≤ 29.9 kg/m2 (body mass index)
• Signed and dated written informed consent prior to admission to the study in accordance with Good Clinical Practice (GCP) and the local legislation

Exclusion Criteria:

• Any finding of the medical examination (including BP, PR, and ECG) deviating from normal and of clinical relevance
• Gastrointestinal, hepatic, renal, respiratory, cardiovascular, metabolic, immunologic, hematologic, oncologic or hormonal disorders
• Surgery of gastrointestinal tract (except appendectomy)
• Diseases of the Central Nervous System (CNS) (such as epilepsy) or psychiatric disorders or neurological disorders
• Relevant history of orthostatic hypotension, fainting spells or blackouts
• Chronic or relevant acute infections
• History of allergy/hypersensitivity (including drug allergy) which is deemed relevant to the trial as judged by the investigator
• Intake of drugs with a long half-life (> 24 h) within 1 month prior to administration of the study drug or during the trial
• Use of any drugs which might influence the results of the trial within 10 days prior to study drug administration or expected during the trial
• Participation in another trial with an investigational drug within 2 months prior to administration or expected during the trial
• Smoker (>10 cigarettes or >3 cigars or >3 pipes/day); inability to abstain from smoking within 5 days before first drug administration until completion of the trial
• Alcohol abuse (>60 g/day)
• Drug abuse
• Blood donation or loss >400 mL, within 1 month prior to study drug administration or expected during the trial
• Clinically relevant laboratory abnormalities

For male subjects:

• Male subjects whose sexual partners are currently not using an adequate method of contraception that would prospectively be maintained during the study, are to be excluded
• Male subjects who are not willing to use condoms are to be excluded

For female subjects:

• Pregnancy
• Positive pregnancy test
• No highly safe method of contraception in women of childbearing potential (in this context, only sterilization or male partner sterilization is considered a highly safe method of contraception). Hormonal contraceptives are not considered adequate due to possible drug interaction with BIRT 2584 XX
• Lactation period