Relationship of desipramine plasma levels to therapeutic response: a critical reappraisal of the data.

The literature on the relationship between desipramine plasma levels and therapeutic response is reviewed. Although no clear pattern has emerged from the available studies, the data suggest that plasma levels of 125 ng/ml should be attained before moderately to severely ill patients are considered nonresponsive to desipramine. An upper therapeutic plasma level of 170 ng/ml may exist for patients with less severe illness. Future studies should control for severity of illness in assessing dose-response relationships.