Is psoral cream good for treating psoriasis?

Psoral cream. Is the creation of a dermatologist in peru that consists (according to its website) petroleum jelly, vitamin a, pine oil based salvia, nicotinic acid, etc & water from the dead sea (which contains many minerals) found no medical studies, just anecdotal testaments. Expensive. Has oily consistency with disagreeable odor. Ask your dermatologist if (s)he knows of this product & if it's effective.