Today's account will indicate first that levodopa (L-dopa) differs from previous drugs in that it may be slowing the progressive deterioration in some patients with parkinsonism. We will then discuss some difficulties encountered by others which have been rare with us. We will consider some questions raised by our own continuous administration of first DL-dopa, and then levodopa. Scientific scrutiny of these questions includes testing of experimental animals so that we can formulate further clinical investigations. We will finally indicate that we do not know the mechanisms of action of levodopa and will propose a hypothesis which may perhaps be testable.
Our clinical experience with levodopa covers to date 48 patients with parkinsonism, as follows: 12 with chronic manganese poisoning including two with muscular dystonia, seven with spontaneous dystonias, one with a dystonia following cyanide poisoning, one hemiplegic, and 20 neurologically normal persons. Most of the latter were