LIQUID-CHROMATOGRAPHIC ANALYSIS OF ANTIEPILEPTIC DRUGS - AN OVERVIEW

Extraction of antiepileptic drugs (AEDs) can be carried out by different procedures which include: (i) protein precipitation, (ii) liquid-liquid and (iii) liquid-solid extraction. The latter yields a cleaner sample and shows efficiency comparable to the other procedures; recovery ranges from 90 to 105% for most AEDs. Types of column include: (i) conventional, (ii) microbore and (iii) high-speed. Compared with conventional and high-speed columns, microbore columns, which have a diameter of 1-2 mm, allow to achieve the highest sensibility (up to double values) and to reduce solvent consume (up to 70 %). High-speed columns, characterized by a length of 3-10 cm and by a reduced packing particle size (0 3-mu-m), make the analysis time more rapid by at least 50%. Reversed phase chromatography is the most versatile technique as compared to the normal phase and to the adsorption chromatography. Detection can be performed at low wavelengths (about 200 nm), which are optimal for AEDs and, subsequently, allow the use of small biological samples (about 100-mu-l). Reproducibility of LC methods is excellent and the within-day and the day to-day CV show values of < 10%.