Psoriasis treatments may be used topically or systemically. We are going to consider the various topical and systemic therapies, their utilization strategies and the problems raised by the particular cases encountered most often.
Psoriasis treatment breaks down into two phases: the clearing phase and the maintenance phase. The aim of the clearing phase is to get rid of the lesions; the aim of the maintenance phase is to avoid relapses. In the clearing phase, effectiveness is the chief consideration; in the maintenance phase, tolerability and the convenience of the drugs become the main concern, since the skin lesions will have disappeared.
It is considered necessary to pursue maintenance therapy for about a year in order to hope for a lasting remission. This important point has never been validated by a clinical study. Such consideration lies on a number of factors: that relapse is usually observed swiftly if treatment is stopped at the end of the clearing phase; that the microcirculatory anomalies will persist for months after the clinical disappearance of the lesions; and that relapse usually begins on the spot of the old plaques as if the skin retained its memory of the inflammation for a long time, perhaps through the persistence of receptors enabling the inflammatory cells to adhere to the endothelial cells.
However, around 30% of patients benefit from prolonged remission, being able to pass the one-year mark after a properly conducted clearing phase, as it has been demonstrated with PUVA therapy and cyclosporine. This prolonged remission seems to be more frequent when the clearing phase is halted progressively rather than suddenly.