Lithium More Effective than Valproate for Bipolar Disorder
According to two studies in 2011, lithium is more effective in treating episodes of bipolar disorder than valproate, while the drugs may be equally effective in reducing suicidality among bipolar patients.
The first study, of more than 4000 Danish patients with bipolar disorder, found that patients taking lithium had fewer hospital visits and were less likely to need new medications than those taking valproate. Patients taking lithium had fewer admissions to a hospital for any type of episode. In addition, patients taking valproate had a higher rate of switching to or adding on treatment with antidepressants, antipsychotics, or anticonvulsants than those taking lithium. The study included up to 12 years of follow-up with the patients and is the largest study with the longest period of follow-up of patients taking valproate or lithium to date. Results were published by Lars Kessing et al. in the British Journal of Psychiatry in July 2011.
In the other study, a randomized controlled trial of 100 patients with bipolar disorder who had attempted suicide at least once in the past, Maria Oquendo of Columbia University found that there were no significant differences in number of suicide attempts, hospitalizations for suicide attempts, or time to a new attempt between patients taking lithium and those taking valproate over a follow-up period of 2.5 years.
Forty-five suicide events, which included attempts, hospitalizations, and changes to medication in response to suicide plans, were experienced by 35 patients (16 who were taking lithium and 19 who were taking valproate). Eighteen suicide attempts were made by 6 patients taking lithium and 8 taking valproate. There were no suicide completions during this study, which was published in Volume 168 of the American Journal of Psychiatry in 2011.
Editor’s Note: Suicide attempts are much more common than completed suicides. It appears that the second study was not large enough or long enough to detect differences in the rate of completed suicides. Older naturalistic studies suggest that treatment results in low suicide rates and that in patients who stop treatment with lithium, the rate of suicide attempts and completion increases dramatically. This is another reason for good responders to treatment regimens that include lithium to continue taking their medications.
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