Chromatographic Method for the Determination of Lamotrigine in Human Plasma and Saliva

A simple, sensitive and precise high performance liquid chromatographic assay for lamotrigine (LTG) is described. Good chromatographic separation was achieved using a 5 μm ACE-5 C18 reverse-phase column and a mobile phase consisting of methanol:acetonitrile:0.01 M potassium phosphate monobasic (30:15:55, v/v/v) adjusted to pH 6.3 and delivered at a flow rate of 1 mL/min. Quantification was performed by measurement of the UV absorbance at a wavelenght of 304 nm. The method was linear in the range of 0.1-6.2 μg/mL with a coeffient of determination, (r = 0.999 ) . The retention time of LTG was 6.8 and 6.2 min in plasma and saliva, respectively. The limit of quantification was 0.10 μg/mL. Recovery from plasma and saliva ranged from 97 to 98 and 96 to 105 %, respectively. Between-day and within day precision expressed as CV % in plasma and saliva were in the range of 0.26 to 6.8. The method was showed to be appropriate for pharmacokinetic (PK) studies and monitoring LTG in saliva and plasma samples.