The present invention provides novel drug formulations for oral administration for diverse medical applications including anticancer, antimetastatic, antibacterial, antifungal, antiprotozoic, antiviral, antiprionic and PDT treatments for diagnostic and therapeutic purposes. In a preferred embodiment the oral drug formulation comprises a photosensitizer and suitable excipients and may be administered in multiple doses over an extended period of time with exposure to activating radiation occurring generally between individual doses or in a light-independent manner. In another preferred embodiment PDT methods for treating hyperplasia and neoplasia, for localizing hyperplasic and neoplasic tissues and pathogen bacteria by fluorescence, for treating infections caused by pathogen bacteria in complex body fluids and for fat reduction, skin disorders and vascular diseases are provided.