The extraction of antiepileptic drugs. Model study on partition coefficients.

To compare the extraction behaviour of hexane, toluene, chloroform, 1,2-dichloroethane, diethylether, ethyl acetate and acetone towards phenobarbital, phenytoin, primidone and carbamazepine, partition coefficients of these drugs between the above solvents and water (saturated with ammonium sulphate when working with acetone) were measured at different pH-conditions. Acetone rendered the highest partition coefficients for all drugs. Ethyl acetate was second in the range, except for carbamazepine, which showed a specific affinity for the chlorinated hydrocarbons.