In patients with bipolar disorder, olanzapine is commonly used to prevent episodes of acute mania. The drug pramipexole can, in theory, undermine the protective effect of olanzapine. Olanzapine is a dopamine D2 receptor antagonist and pramipexole is a mixed dopamine D2/D3 receptor agonist. These drugs may therefore theoretically counteract their pharmacological effects. To date, there are no known cases in the literature where this interaction has been described.
We report on a case where a patient with bipolar disorder developed mania after taking pramipexole in combination with olanzapine, and describe the pharmacological background of this interaction.
A patient with bipolar I disorder was hospitalized with a manic episode characterized by agitation and insomnia after taking pramipexole for restless leg syndrome (RLS) in combination with olanzapine. Co-medication, i.e., lithium and mirtazapine, and other circumstances are not likely to have contributed to this effect.
There is a probable interaction between pramipexole and olanzapine, where pramipexole undermines the protective effect of olanzapine, provoking an episode of acute mania and hospitalization. This interaction is of clinical importance since pramipexole is the treatment of choice for RLS, a condition often seen in end-stage renal disease, and has also been investigated as an antidepressant therapy in patients with bipolar disorder.