Effectiveness and Mood Conversion Rate of Short-Term Fluoxetine Monotherapy in Patients With Rapid Cycling Bipolar II Depression Versus Patients With Nonrapid Cycling Bipolar II Depression:

Objective: We examined the effectiveness and mood conversion rate of fluoxetine monotherapy in patients with rapid cycling bipolar II depression versus patients with nonrapid cycling bipolar II depression. We hypothesized that there would be reduced antidepressant effectiveness and a greater mood conversion rate over time in patients with rapid cycling. Methods: Open-label fluoxetine monotherapy 10 to 80 mg daily was administered for up to 14 weeks in 42 outpatients with rapid cycling versus 124 outpatients with nonrapid cycling. Outcome measures included the change over time in depression ratings, the proportion of treatment responders and remitters, change over time in mania ratings, and frequency of syndromal and subsyndromal hypomanic episodes. Results: There was a greater reduction in depression rating scores in the patients with rapid cycling versus those with nonrapid cycling (P = 0.04), with similar rates of response (P = 0.18) and remission (P = 0.69). Change in mean mania rating scores was similar in the patients with rapid cycling versus those with nonrapid cycling (P = 0.28). Hypomanic symptoms occurred in a similar proportion of the patients with rapid cycling versus those with nonrapid cycling (P = 0.99). Hypomanic episodes occurred in 5.4% (95% confidence interval [CI], 0.7Y18.2) of the patients with rapid cycling versus 3.6% (95% CI, 1.0Y8.9) of those with nonrapid cycling (P = 0.65). Subsyndromal hypomania occurred in 13.5% (95% CI, 4.5Y28.8) of the patients with rapid cycling versus 9.0% (95% CI, 4.4Y15.9) of those with nonrapid cycling (P = 0.43). Conclusion: In contrast to reports of reduced effectiveness and increased mood conversion rates in patients with rapid cycling bipolar disorder taking antidepressants, we found greater effectiveness and similar hypomania rates during fluoxetine monotherapy in the patients with rapid cycling bipolar II depression versus those with nonrapid cycling bipolar II depression.