[Pharmaceutical interviews in onco-haematology and so-called 'natural' products: An example illustrated by cannabidiol (CBD)].

In recent years, there have been significant changes in the way cancer patients are treated. The use of oral anti-tumour therapies has accelerated outpatient treatment. In response, healthcare professionals have organised themselves to design multidisciplinary information and support pathways for the initiation of treatment. Pharmacists, as drug experts, are involved to detect and analyse drug interactions. By taking control of their illness, patients are encouraged to seek their own solutions, sometimes using complementary and alternative medicines. The use of cannabidiol in a patient suffering from chronic myeloid leukaemia in 4th line treatment illustrates this problem. High-dose cannabidiol is a strong inhibitor of cytochrome 3A4 and P-gP protein, and a weak inhibitor of cytochromes 2C19, 2B6, 2D6, 2C9, 2C8 and 1A2, as well as UGT1A9 and 2B7. Case reports complement these elements by reporting clinically significant inhibition when lower doses are used. According to current recommendations, the first four lines of treatment for chronic myeloid leukaemia are major substrates of cytochrome 3A4. There is a risk of drug-drug interaction/herb-drug interaction, even at low doses. The use of cannabidiol is strongly discouraged. Pharmacists, through their participation in multidisciplinary interviews for the initiation of oral anti-cancer therapies, contribute their expertise in the detection and analysis of potentially clinically significant interactions.