Prostate cancer is the most common form of cancer in men in the Western world. One-third of the patients with localised prostate cancer will develop recurrent disease, localised disease spread or distant metastases. The presence of distant metastases is an indication for primary palliative hormone therapy. Intervention in the testosterone metabolism using hormone therapy is frequently accompanied by side effects and has a negative influence on the quality of life. Almost all prostate cancer patients show disease progression while on primary hormone therapy, despite having testosterone concentrations at castration level; they are then said to have castration-resistant prostate cancer (CRPC). The CYP17 inhibitor abiraterone and the non-steroidal anti-androgen enzalutamide are second-generation hormone therapies for metastatic CRPC both before and after treatment with standard docetaxel-based chemotherapy. Abiraterone and enzalutamide can lead to many interactions with other drugs or food. This can lead to higher or lower levels of both the hormone therapy and comedications.