PHARMACOKINETICS OF THE INDIVIDUAL ENANTIOMERS OF VIGABATRIN (GAMMA-VINYL GABA) IN EPILEPTIC CHILDREN

1. The pharmacokinetics of the enantiomers of vigabatrin were investigated after oral administration of a single 50 mg kg‐1 dose of the racemate to two groups of six epileptic children (I: 5 months‐2 years, II: 4‐14 years). 2. The mean (+/− s.d.) values of maximum plasma concentration and area under the plasma concentration‐time curve of the R(‐) enantiomer were significantly higher than those of S(+) vigabatrin in both groups: R(‐) Cmax: 21 +/− 6.6 (I)‐41.3 +/− 13.9 (II) vs S(+) Cmax: 13.9 +/− 4.5 (I)‐23.8 +/− 12.2 (II) mg l‐1; R(‐) AUC: 106 +/− 28.5 (I)‐147 +/− 34 (II) vs S(+) AUC: 90.9 +/− 27.9 (I)‐117 +/− 26 (II) mg l‐1 h. In group I, the half‐life of the R(‐) isomer was significantly shorter than that of the S(+) isomer; in group II, the half‐lives were comparable. 3. For the R(‐) enantiomer the area under the curve, and the elimination half‐life increased linearly with age. 4. During chronic administration (50 mg kg‐1 vigabatrin racemate twice a day for 4 days), the morning trough plasma drug concentrations did not increase. 1990 The British Pharmacological Society