Psoriasis is treated by oral administration of a pharmaceutical composition containing a nitrone spin trap such as α-phenyl t-butyl nitrone (PBN) and derivatives thereof. Preferred compositions and method of treatments further comprise at least one adjunct ingredient including fatty acid esters of ascorbic acid such as ascorbyl palmitate and ascorbyl stearate. The pharmaceutical composition can be prepared as an immediate release formulation or controlled released formulations.
