Phase I trials involve healthy subjects and aim at testing the tolerability of a new medicinal product. Phase II trials are dose-finding studies with patients suffering from the disease in question. Phase III trials shall confirm safety and efficacy of the investigational medicinal product among a large patient population. Only once those three phases have been successfully completed, i.e. the positive risk benefit ratio has been confirmed, the manufacturer may apply for a marketing license for the new medicinal product. Phase IV trials are conducted following the product’s market launch. These are long-term studies within the field of pharmacovigilance aiming at discovering rare side effects and interactions with other drugs.