Evaluation of the influence of particle size of aerosolized AMP on bronchial responsiveness in patients with asthma and the effects of treatment with ciclesonide versus fluticasone (protocol BY9010/NL101).

1. Written informed consent;
2. Outpatients males or females;
3. Good health with the exception of asthma;
4. Age 18 up to and including 60 years;
5. History of bronchial asthma (according to GINA 2004);
6. FEV1 > 1.20L, measured at least 6 hours after the last use of rescue medication;
7. Atopy shown by positive skin prick test to common allergen (historic tests are accepted, if results are available and test was done within 3 years prior to visit B0);
8. Stable asthma (no exacerbation or relevant respiratory tract infection within 2 months prior to the study);
9. Patients who are steroid-naive or who have been pretreated with inhaled glucocorticosteroid of up to 500 µg/d fluticasone or equivalent alone or in combination with long-acting beta-agonists at a constant dosage for at least 28 days prior to visit B0.

The presence of any one of the following will cause exclusion of the patient:
a. Diseases and health status:
1. Clinically relevant abnormal laboratory values suggesting an unknown disease and requiring further clinical evaluation;
2. Concomitant severe diseases, diseases expected to interfere with the outcome of the study and diseases which are contra-indications for the use of inhaled steroids (e.g. active or inactive pulmonary tuberculosis or relevant fungal, bacterial or viral infections of the lower respiratory tract demanding specific treatment);
3. Suffering from COPD (i.e. chronic bronchitis or emphysema) and/or other relevant lung diseases causing alternating impairment in lung function;
4. Hospitalization because of asthma during the previous 6 months prior to visit B0;
5. One asthma exacerbation within 2 months or more than 3 exacerbations within the last year prior to visit B0;
6. Ex-smokers with > 10 pack years, or having smoked within 1 year prior to visit B0;
7. Current smokers;
8. Positive response to saline challenge at baseline visits B1, B2 or B3 (defined as 20% fall in FEV1);
9. PC20 > 160 mg/ml to AMP-ATS at B1;
10. FEV1 ≤ 1.20 l prior to each bronchial challenge test;

b. Medications:
11. Use of systemic steroids within 4 weeks (injectable depot steroids 6 weeks) prior to visit B0 or more than 1 course during the last 6 months prior to visit B0;
12. Use of other drugs not allowed (see 7.4);
13. Washout times of drugs defined under 7.4 cannot be adhered to;
14. Known or suspected hypersensitivity to inhaled steroids or to the other excipients of the inhalatio devices;
15. Intolerance to salbutamol and excipients;
16. Beginning of immunotherapy during the patient's participation in the study or having begun an immunotherapy less than 3 months prior to visit B0 or alternation i regimen of an immunotherapy during the study period;

c. Common criteria:
17. Pregnancy;
18. Intention to become pregnant during the course of the study;
19. Breast feeding;
20. Lack of safe contraception:
Safe contraception is defined as follows:
female patients of childbearing potential not using and not willing to continue using a medically reliable method of contraception for the entire study duration such as oral, injectable or implantable contraceptives or intrauterine contraceptive devices unless they are surgically sterilized/hysterectomized or post-menopausal > 1 year or who are not using any other method considered sufficiently reliable by the investigator in individual cases;
21. Participation in another study within the 30 days preceding and during the present study;
22. Previous enrollment into the current study;
23. Enrollment of the investigator, his/her family members, employeees and other dependent persons;
24. Known or suspected non-compliance, alcohol or drug abuse;
25. Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders;
26. Reversal of sleep pattern (e.g. night shift workers).