<unk> (oral) is a naturally occurring photoactive substance that is FDA approved for the treatment of severe, recalcitrant, disabling psoriasis not adequately responsive to other forms of therapy and when the diagnosis has been supported by biopsy. It should be used with long wave ultraviolet radiation. There is a Black Box Warning for this drug as shown here.  Common adverse reactions include erythema, pain of skin, pruritus, nausea, dizziness, headache, fatigue.
Methoxsalen 
Trioxsalen
Isothipendyl
Naloxegol
Mannosulfan
Perflubron
Cloethocarb
Dicyclomine