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Imipramine: Do Metabolite Plasma Levels Affect Treatment Response?
Roan Y N Kasanmonadi1, Astrid M Kamperman1, Birgit C P Koch2
1Department of Psychiatry, Erasmus Medical Center.
Journal of Clinical Psychopharmacology
|April 24, 2026
Summary
Higher desipramine levels in patients with major depression were linked to poorer imipramine treatment response. Monitoring desipramine levels alongside imipramine is crucial for effective therapeutic drug monitoring (TDM).
Area of Science:
- Pharmacology
- Psychiatry
- Clinical Chemistry
Background:
- Imipramine and its metabolite, desipramine, are routinely monitored during treatment.
- Individual plasma levels of imipramine and desipramine are often overlooked despite differing pharmacokinetic properties.
- Previous studies suggest high desipramine levels may negatively impact treatment efficacy in generalized anxiety disorder.
Purpose of the Study:
- To explore the relationship between imipramine and desipramine plasma levels and treatment response in depressed inpatients.
- To investigate the impact of metabolite levels on imipramine's therapeutic effect.
Main Methods:
- An exploratory retrospective study of 70 inpatients with major depressive disorder treated with imipramine for 5 weeks.
- Weekly measurement of combined imipramine and desipramine plasma levels with dose adjustments.
- Assessment of treatment response using the Hamilton Rating Scale for Depression (HDRS17) and comparison of plasma levels between responders and nonresponders.
Main Results:
- Nonresponders exhibited significantly higher plasma levels of desipramine and combined imipramine/desipramine compared to responders.
- No significant difference in imipramine plasma levels was observed between responders and nonresponders.
- Concomitant use of CYP2D6 or CYP2C19 inhibitors did not significantly alter plasma levels.
Conclusions:
- Elevated desipramine plasma levels in nonresponders suggest a negative impact on imipramine's therapeutic efficacy.
- The findings highlight the importance of considering individual metabolite plasma levels in therapeutic drug monitoring (TDM) for imipramine.
- Monitoring desipramine levels may improve treatment outcomes for major depression.
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