1. Department of Pharmaceutics and Biopharmacy, University of Marburg, Ketzerbach 63, 35032 Marburg, Germany, Procter & Gamble Pharmaceuticals, Dr. Otto Röhm-Strasse 2-4, 64331 Weiterstadt, Germany, and Schwarz Pharma AG, Alfred-Nobel-Strasse 10, 40789 Monheim, Germany