Serotonin Syndrome after Discontinuation of Olanzapine in a Combined Treatment with Duloxetine –Case Report

Combinations of serotonergic antidepressants and atypical antipsychotics and higher doses of antidepressants are common strategies in the management of treatment-resistant depression. This approach is associated with an increased risk of adverse drug interactions. We report on a patient who was treated with high-dose duloxetine in combination with olanzapine and developed a serotonin syndrome after withdrawal of olanzapine. Previous studies suggest that the activation of 5HT-2A receptors in the brain contribute to the pathophysiology of serotonin syndrome. Olanzapine, like many other atypical antipsychotics, shows a high affinity and occupancy of 5HT-2A receptors, blocking postsynaptic serotonergic action. Therefore, discontinuation of olanzapine in a patient on a high-dose SSRI or SNRI may precipitate a serotonin syndrome. We hypothesize that a serotonin syndrome may be prevented by olanzapine co-administration.

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