Effect of Citalopram on Blood Desipramine Levels.

Abstract

Sir: We report a case of treatment-resistant major depression and panic disorder with agoraphobia treated with desipramine and augmented with citalopram without altered blood levels of desipramine. Case report: Ms. A is a 54-year-old married white woman with DSM-IV major depression and panic disorder with agoraphobia. She has a history of panic attacks since age 20 and had presented 1 year earlier for psychiatric consultation owing to increasing symptoms of depression, which included low mood, poor concentration, suicidal thoughts, and despair. She had difficulty going to large shops and gatherings and also had difficulty leaving home. There was no significant past psychiatric history of hospitalization or suicide attempts. She had been unresponsive to a combination of fluoxetine, 60 mg daily, buspirone, 15 mg t.i.d., and trazodone, 150 mg at bedtime, prescribed by her family physician. Her medical history was significant for hypertension and knee problems. She had been in individual psychotherapy for 2 years. The family history was significant for the mother who had anxiety attacks that had never been treated. There was no past history of drug or alcohol abuse. Results of her laboratory tests had been unremarkable. The patient was gradually tapered off fluoxetine and started on desipramine treatment, which was titrated over the course of 3 months to a dosage of 300 mg daily in divided doses (serum level = 234 ng/mL). Clonazepam, 1 mg t.i.d., was added to control anticipatory anxiety. With desipramine, the patient's sleep improved and the crying spells were reduced in frequency and intensity. Suicidal thoughts were still present, but decreased in intensity. Regarding symptoms of panic, she indicated, “I still have my moments.” Although she wanted to, she was still unable to return to work. Owing to persistence of depressive and panic symptoms, desipramine was augmented with citalopram, 10 mg daily, which was titrated after 1 week to 20 mg daily without side effects. At this time, the clonazepam dosage was decreased to 1 mg b.i.d. The desipramine dosage was maintained at 300 mg daily in divided dosage. The serum desipramine level was 267 ng/mL 1 month after the augmentation. There were no adverse reactions and no marked elevation of the blood level of desipramine with the addition of citalopram. Different combinations of selective serotonin reuptake inhibitors (SSRIs) and tricyclic amines (TCAs) for treatment-resistant depression vary in efficacy and safety. During coadministration of SSRIs and TCAs, blood levels must be carefully monitored due to elevation of TCA levels.1 Citalopram has demonstrated superiority to placebo in major depression2 and in panic disorder.3 There have been no reports of clinical adverse reactions when citalopram is coadministered with a TCA.4 In addition, citalopram has demonstrated safety when coadministered with digoxin5 and warfarin.6 Further studies are warranted to determine the potential for adverse effects of citalopram in combination with TCAs and other SSRIs.