Summary:A study was conducted to assess the impact of single dosing and different dosing intervals of vigabatrin [gamma vinyl GABA (GVG)] in 11 patients with drug‐resistant complex partial seizures. Cerebrospinal fluid (CSF) concentrations of total GABA, free GABA, homocarnosine, homovanillic acid (HVA), GVG, and 5‐ hydroxyindolacetic acid were measured up to seven days after a single dose. GVG levels were maximal within 24 h, suggesting that GVG acts to inhibit GABA‐transami‐nase, and may also increase biogenic