The objective of the study is to obtain information about safety, tolerability and pharmacokinetics of BIIR 561 CL after single intravenous administration of increasing doses in healthy male volunteers

Inclusion Criteria:

• Healthy male volunteers
• Age 21 to 50 years
• Broca index from -20% to +20%
• Written informed consent prior to admission to the study

Exclusion Criteria:

• Medical examination, laboratory tests or ECG judged by the investigator to differ significantly from normal clinical values
• Known gastrointestinal, hepatic, renal, respiratory, cardiovascular, metabolic, immunological or hormonal disorders
• Known diseases of the central nervous system (CNS) (such as epilepsy), CNS trauma in their medical history or with psychiatric or neurological disorders
• Known history of orthostatic hypotension, fainting spells or blackouts
• Chronic or relevant acute infections
• Allergy/hypersensitivity (including drug allergy) which is deemed relevant to the trial as judged by the investigator
• Intake of a drug with a long half-life (> 24 hours) within at least one month or less than ten half-lives of the respective drug before enrolment in the study
• Intake of any other drug which might influence the results of the trial during the week previous to the start of the study
• Participation in another study with an investigational drug within the last two - months preceding this study
• Smoker (> 10 cigarettes or 3 cigars or 3 pipes/day)
• Alcohol use of more than 60 g per day
• Drug dependency
• Excessive physical activities (e.g. competitive sports) within the last week before the study
• Blood donation within the last 4 weeks (>= 100 ml)