Quetiapine for Insomnia Associated with Refractory Depression Exacerbated by Phenelzine

Abstract

To report the successful treatment of phenelzine-associated insomnia with low-dose quetiapine in a patient with refractory depression. A 42-year-old white man with severe major depression unresponsive to selective serotonin-reuptake inhibitors, bupropion, and tricyclic antidepressants improved following treatment with the monoamine oxidase inhibitor (MAOI) phenelzine. Insomnia, present to a moderate degree prior to antidepressant therapy, worsened markedly following phenelzine treatment and failed to respond to diphenhydramine, temazepam, triazolam, clonazepam, zolpidem, or trazodone given at high therapeutic doses. Sleep disturbance resolved with low-dose (50 mg) adjunctive quetiapine, with no adverse effects. Major depression refractory to standard therapy is a common and serious condition. Some cases respond to MAOIs; however, orthostatic hypotension and insomnia frequently occur. Potentially serious MAOI interactions with psychotropic drugs have raised concerns about combining these agents. In this case, a failure of a number of other medications known to treat MAOI-associated insomnia safely prompted a trial of quetiapine. Despite the possibility that enhanced serotonergic activity might have resulted in serotonin syndrome, no adverse interactions between phenelzine and quetiapine were noted. The use of low-dose, once-daily quetiapine, along with its unique binding properties, may account for its increased safety in combination with phenelzine. This case illustrates that low-dose quetiapine may be an alternative treatment for phenelzine-associated insomnia. Further case reports are needed to establish the safety and effectiveness of combining these agents.