The choice of pharmacotherapy for the treatment of bipolar I disorder should balance acute efficacy and long-term effectiveness with minimal side effects. During acute treatment, the primary goal is rapid stabilisation of symptoms, whereas the goal for the long-term management of bipolar I disorder should include relapse prevention, maintenance of a stable mood, and minimise risk of comorbid conditions.1

Despite the shift in treatment goals between the acute and the maintenance phase, if a patient responds well to the agent used in the acute phase, this agent frequently will be continued in the maintenance phase. However, achieving continued stability may collide with the goals of minimising the adverse-effect burden associated with treatment, and the subsequent goal of improving patient functioning and quality of life. Sometimes, changing medication regimens may help achieve a balance between efficacy and side-effect burden. However, switching may also be associated with an increased risk of destabilisation. Evidence has shown that patients with bipolar I disorder often have a predominant episode polarity, which is a predictor of treatment response.2 Therefore, when assessing long-term treatment options, consideration should be given from the outset to the available clinical evidence for preventing the recurrence of mood episodes, as well as the predominant polarity of the patient.3

Because patient polarity plays an important role in the success of pharmacotherapy, this presentation will review the concept of predominant polarity in clinical practice and discuss the potential value of considering a drug's polarity index in the development of individualised long-term treatment regimens.