How do I interpret clozapine or norclozapine blood, serum or plasma levels, what do these mean?

Clinician assessment of symptoms and side effects is the primary means of evaluating and adjusting clozapine treatment. However, there are circumstances when a clinician may find a clozapine blood level to be useful: when there are questions about medication adherence, when clozapine is less effective than expected, when there are more side effects than expected, or when there could be medication interactions. Clozapine levels are usually drawn more than 3 days after a patient is stable on a dose. The level should be drawn about 12 hours after the patient’s last dose. To interpret blood levels, contact your clinician.


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