The objective of the study is to obtain information about the safety and tolerability of BIIF 1149 BS45 (single dose: 40, 65, 100 mg), to determine the pharmacologically active dose (range) by performing a citric acid challenge test and to obtain preliminary pharmacokinetic data.

Inclusion Criteria:

• Healthy males, based on a complete medical examination
• Age range from 21 to 50 years
• +/- 20 % of their normal weight (Broca-Index)
• Written informed consent

Exclusion Criteria:

• Volunteers will be excluded from the study if the results of the medical examination or laboratory tests are judged by the clinical investigator to differ significantly from normal clinical values
• Volunteers with known gastrointestinal, hepatic, renal, respiratory, cardiovascular, metabolic, immunological or hormonal disorders
• Volunteers with diseases of the central nervous system (such as epilepsy) or with psychiatric disorders
• Volunteers with known history of orthostatic hypotension, fainting spells or blackouts
• Volunteers with chronic or relevant acute infections (especially respiratory infections, cough)
• Volunteers with history of allergy/hypersensitivity (including drug allergy) which is deemed relevant to the trial as judged by the investigator
• Volunteers who have taken a drug with a long half-life (≥ 24 hours) within ten half-lives of the respective drug before enrolment in the study
• Volunteers who received any other drugs which might influence the results of the study during the week prior to the start of the study
• Volunteers who have participated in another study with an investigational drug within the last 2 months preceding this study
• Volunteers who smoke more than 10 cigarettes (or equivalent) per day
• Volunteers who are not able to refrain from smoking on study days
• Volunteers who drink more than 40 g of alcohol per day
• Volunteers who are dependent on drugs
• Volunteers who are participated in excessive physical activities (e.g. competitive sports) during the last week before the study
• Volunteers who have donated blood (≥ 100 ml) within the last four weeks