Volume 21 of "Progress in Drug Research" contains 5 contributions from various areas of drug research and therapy. As in previous volumes, in the present volume the authors have also tried not only to summarise the current status of particular fields of drug research, but also to provide leads for future research activity. The various contributions in this volume will be of especial value not only to those actively concerned in resolving the diverse problems in drug research, but also to those who wish to keep abreast ofthe latest developments in- fluencing modem therapy. In addition, it is believed that volume 21 and the previous 20 volumes of "Progress in Drug Research" so far published represent a useful reference work of an encyclopaedic character. The editor would also like to take this opportunity of expressing his gratitude to Dr. A. Naffor carefully working over the manuscripts and correcting proofs. Thanks are also due to the publishers and the printers, Druckerei Birkhauser, especially to Dr. A. Birkhauser, Th. Birkhiiuser and C. Einsele, for their painstaking work on the printing and lay-out of the volume. August 1977 Dr. E. JUCKER Sandoz AG, Basel Vorwort Der 21.Band der "F ortschritte der Arzneimittelforschung" umfasst 5 Beitriige aus verschiedenen Gebieten der Arzneimittelforschung> und der Therapie.
