- Patients with known photosensitivity disorders (xeroderma pigmentosa, porphyria etc). Patients who do not agree to use sunglasses and sun blocker (with SPF >30 to UVB and a high degree of protection against UVA) if exposed to sunlight during the course of the study and for 3 months after the last dose. Patients who plan to use sun beds or tanning booths during the course of the study and within 3 months after the last dose are not eligible.