Corticosteroids, antibiotics 4 weeks prior to study day 1 and during conduct of study Retinoids Ciclosporin Methotrexate Fumaric acid esters 3 months prior to study day 1 and during conduct of study Anti-inflammatory substances, NSAIDs 2 weeks prior to study day 1 and during conduct of study Biologics 6 months prior to study day 1 and during conduct of study Planned initiation of, or changes to concomitant medication that could affect Psoriasis (e.g. beta blockers, anti-malaria drugs, lithium) 8 weeks before study start and during study