A nationwide study of intracellular drug
metabolite concentrations in children
prescribed 6-mercaptopurine for the
treatment of lymphoblastic leukaemia was
carried out to assess interpatient variability
at a standardised dose. Nine children
(2% of the total) had completely undetectable
metabolites, indicative of noncompliance.
Five were adolescents, but
otherwise they had no obvious distinguishing
characteristics. Not taking any
6-mercaptopurine at all is uncommon,
but the problem cannot be predicted. The
total number of children who do not comply
cannot be determined from this study,
but the nine children described represent
only a fraction of these