- Valproic acid's well-known teratogenicity limits its use in women of childbearing age. Valnoctamide is an analog of valproate that does not undergo biotransformation to the corresponding free acid. In mice, valnoctamide has been shown to be distinctly less teratogenic than valproate. Valnoctamide is an anticonvulsant, and we hypothesized that valnoctamide is antimanic. We performed a double-blind, five-week, add-on, controlled trial of valnoctamide in mania. Patients were treated with risperidone at doses of the physician's discretion. Valnoctamide or placebo was begun at doses of 600 mg/day and increased to 1200 mg after four days. Weekly ratings by a psychiatrist blind to the study drug were conducted using the Brief Psychiatric Rating Scale (BPRS), the Young Mania Rating Scale (YMRS), and the Clinical Global Impression (CGI). Fifteen valnoctamide patients and 17 placebo patients completed at least one post-baseline week and were included in data analysis. In all efficacy measures valnoctamide was more effective than placebo as an add-on to risperidone, using two-way analysis of variance (ANOVA) with time as the within-subject factor. Two-way ANOVA showed a significant effect of time (p < 0.001) and significant interaction between treatment and time (YMRS: p = 0.012; BPRS: p = 0.007; CGI: p = 0.003). Differences between valnoctamide and placebo were significant from week 3 to week 5. Valnoctamide could be an important valproate substitute for women of childbearing age with bipolar disorder who may become pregnant.