Despite the fact that some ADRs such as insomnia, anxiety, and suicide attempt failed to have a statistically significant association in the univariate statistical models, when grouping them, including nightmares, as CNS ADRs, associations with the CYP2B6 c.516G>T (rs3745274) T/T genotype and the toxicity, both in the codominant and recessive models, were observed (OR = 30.00, p = 0.011; OR = 14.99, p = 0.021, respectively), but not in the dominant model (OR = 5.08, p = 0.061). Here, CYP2B6 is linked to insomnia.