(+/-)-2-Propyl-4-pentenoic Acid Methyl Ester-d3 is the isotope labelled analog of (+/-)-2-Propyl-4-pentenoic Acid Methyl Ester (P838425); the methyl ester derivative of (+/-)-2-Propyl-4-pentenoic Acid (P838305) which is a metabolite of Valproic Acid (V094750), an anticonvulsant agent that also acts as a mood stabilizer for the treatment of bipolar disorder.