Ro 10-9359 [Ethyl all-trans-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-2,4,6,8-nonatetraenoate] is a retinoic acid derivative, selected for study because of a better tolerance than retinoic acid. This was shown in animal experiments. Ro 10-9359 was an extremely potent antipsoriatic drug in previous clinical experience. The well-known association between psoriasis and pustulosis palmoplantaris was a motivation to evaluate Ro 10-9359 also in the last-mentioned disease, which is notoriously resistant to treatment. In this study 30 patients were given either 75 mg/day of Ro 10-9359 or 200 mg twice every wk according to a randomized pattern. All patients had suffered from the disease for at least 2 yr without any spontaneous remission during the yr preceding the trial. After a treatment period of about 2 wk with Ro 10-9359 hyperkeratotic scales had usually disappeared and 2 wk later there were in general significantly less pustular lesions. The treatment continued for 8 wk, and at this time the average reduction of the number of pustules was 80%. The daily dosage apparently gave better results and was also better tolerated than the twice-weekly dosage. Side effects were common, but generally mild. Remission lasted 1 mo. after cessation of therapy, on the average.
