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Imipramine in panic disorder. 2. Effects on α2-adrenoceptor function.
Journal of Psychopharmacology (Oxford, England)
|January 28, 2012
Summary
Imipramine treatment for panic disorder reduced alpha-2 adrenoceptor sensitivity, indicated by smaller clonidine-induced MHPG, blood pressure, and heart rate changes. These alterations partially explain antidepressant effects in panic disorder.
Area of Science:
- Neuroscience
- Psychopharmacology
- Clinical Psychiatry
Background:
- Panic disorder is associated with altered alpha-2 adrenoceptor sensitivity.
- Clonidine challenge testing assesses adrenoceptor function.
- Imipramine is a common antidepressant treatment for panic disorder.
Purpose of the Study:
- To investigate the effects of imipramine treatment on clonidine-induced responses in panic disorder patients.
- To assess changes in biochemical, physiological, hormonal, and psychological parameters before and after imipramine therapy.
Main Methods:
- Six patients with panic disorder underwent clonidine challenge testing.
- Tests were performed before and after a course of imipramine treatment.
- Measurements included plasma MHPG, blood pressure, heart rate, growth hormone, and sedation levels.
Main Results:
- Imipramine treatment significantly reduced the clonidine-induced fall in plasma MHPG.
- Smaller decreases in diastolic blood pressure and heart rate were observed post-treatment.
- Growth hormone and sedation responses to clonidine remained unaltered by imipramine.
Conclusions:
- Imipramine treatment appears to reduce the sensitivity of central alpha-2 adrenoceptors in panic disorder patients.
- These adrenoceptor changes may partially contribute to the therapeutic efficacy of imipramine.
- The observed alterations do not fully account for the antidepressant mechanisms in panic disorder.
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