The title compound, C22H24N2O7S·0.5C2H5OH·0.5H2O {systematic name: (S)-4-acetamido-2-[1-(3-eth­oxy-4-meth­oxy­phen­yl)-2-(methyl­sulfon­yl)eth­yl]iso­indo­line-1,3-dione ethanol hemisolvate hemihydrate}, is a novel solvatomorph of apremilast (AP), which is an inhibitor of phosphodiesterase 4 (PDE4) and is indicated for the treatment of adult patients with active psoriatic arthritis. This evidence concerns the gene PDE4A and psoriatic arthritis.