False-positive methadone drug screens during quetiapine treatment.

To the Editor: Quetiapine is a widely used antipsychotic and mood stabilizing compound. So far, false-positive methadone urine drug screens during quetiapine therapy have been described for 3 adults1 and 12 adolescents.2 Here, we report a case series of 10 inpatients, 4 men and 6 women from 22 to 48 years old, suffering from mood or psychotic disorders who tested positive for methadone. Since such false-positive methadone screenings may seriously affect the therapeutic relationship, this potential interaction is highly relevant for clinicians.