Inclusion Criteria:

1. Signed and dated written informed consent in accordance with the GCP and local legislation.
2. Patients completing the entire treatment period as a double blind trial whether or not they have been treated with rescue medication.

Exclusion Criteria:

1. Patients who meet one or more of the withdrawal criteria of the treatment period of the previous trial.

2. Pre-menopausal women (last menstruation =< 1 year prior to signing informed consent) who:

   • are nursing or pregnant,
   • or are of child-bearing potential and are not practicing an acceptable method of birth control, or do not plan to continue using this method throughout the study and do not agree to submit to periodic pregnancy testing during participation in the trial. Acceptable methods of birth control include transdermal patch, intra uterine devices/systems (IUDs/IUSs), oral, implantable or injectable contraceptives, true sexual abstinence (when this is in line with the preferred and usual lifestyle of the patient; periodic abstinence [e.g. calendar, ovulation, symptothermal, post-ovulation methods] and withdrawal are not acceptable methods of birth control) and vasectomised partners. No exception will be made.
3. Alcohol abuse within the 3 months prior to informed consent that would interfere with trial participation.
4. Drug abuse which, in the opinion of the investigator, would interfere with trial participation.
5. Any other clinical condition which, in the opinion of the investigator, would not allow safe completion of the protocol and safe administration of the trial medication.