A study in healthy subjects found no evidence of an interaction between
clozapine and
erythromycin, but three case reports describe
clozapine toxicity (seizures in one patient, drowsiness, incoordination and incontinence in another, and
neutropenia in the third) when the patients also took
erythromycin. Quetiapine levels are increased by
erythromycin.
The
clinical importance of these interactions is uncertain, but bear them in mind in case of an unexpected response to treatment. The manufacturers suggest that lower quetiapine doses should be considered if
macrolides are given. Note that not all
macrolides would be expected to interact, see
macrolides.