Fontenot, M. B., Anderson, G. M. 2007. Fluoxetine dose finding study for treatment of self-injurious behavior in Macaca mulatta. American Journal of Primatology 69(S1), 48. (30th Meeting of the American Society of Primatologists Scientific Program, Abstract #38)

Based on clinical efficacy in the short-term treatment of self-injurious behavior in macaques, we performed a dose-finding study to establish optimal doses of fluoxetine (selective serotonin reuptake inhibitor). The subjects were 11 male (aged 7 – 15 years) rhesus macaques with a history of self-injurious stereotypic behavior. Subjects received either fluoxetine (n=6; 0.5, 1.0, 2.0, 4.0 and 8.0 mg/kg orally, once per day) or a placebo (n=5). Dose levels were increased at four-week intervals for four months. Twenty-minute focal behavioral samples were collected from each animal twice per week balanced for time of day. Cerebrospinal fluid (CSF) samples were obtained at monthly intervals and assayed for monoamine metabolites. Animals consumed the fluoxetine-medicated wafer without difficultly at doses of 0.5 – 4.0 mg/kg. When fluoxetine was increased to 8.0 mg/kg, compliance decreased to 67%. Results of repeated measures ANOVA [α criterion: p<0.05] indicated that fluoxetine treatment was significantly more effective in decreasing rates of self-biting compared to placebo. The greatest reduction in self-biting (to 30% of baseline rates) occurred at a dose of 2.0 mg/kg. The serotonin metabolite, 5-hydroxyindoleacetic acid, was significantly decreased in CSF among fluoxetine treated animals. The results indicate that fluoxetine at 2.0 mg/kg once per day should be used to evaluate the long-term effects of serotonin reuptake inhibition on self-biting in rhesus macaques.