Drug Monitoring of Orally Administered 8-Methoxypsoralen in Patients Treated with Extracorporeal Photopheresis

Recently extracorporeal photopheresis (ECP), a new therapy involving extracorporeal activation of orally administered 8-methoxypsoralen (8-MOP), has been established for the treatment of different skin diseases. The pharmacokinetic profile of 8-MOP has been pursued in a clinical study which aimed to assess the efficacy of ECP in patients with progressive systemic sclerosis and cutaneous T-cell lymphoma. However, the enormous intraindividual variations in plasma as well as buffy coat concentrations affect the efficacy of oral 8-MOP therapy. Therefore, the introduction of a liquid 8-MOP formulation enabling the direct administration of the drug into the treatment bag of the ECP device is challenging.