Leary E, et al. - An exploration was carried out of the changes in lamotrigine (LTG) serum concentrations immediately following sodium valproate (VPA) discontinuation in healthy adult subjects. Reversible pharmacokinetic interaction was determined between LTG and VPA. It was also found that de-inhibition followed a predictable time course. Furthermore, 10-14 days after VPA discontinuation, complete offset, or reversal of this interaction had taken place. Findings affirmed that LTG oral clearance could be inhibited by very low concentrations of VPA. Hence, the conversion algorithm was supported, suggested by the manufacturer, which guided the clinician. Clinically beneficial information was yielded in developing a dosing algorithm for converting patients to LTG monotherapy.