Uptake of phenytoin by tissues of Mongolian gerbils

1. Radioactive phenytoin was extracted from brain, cerebellum liver and kidney of i.p. injected Mongolian gerbils that were killed at hourly intervals. 2. The drug was extracted by two procedures. Procedure I involved acidification and chloroform extraction, the other, procedure II, an alkaline extraction, acidification and solubilization in chloroform (II). 3. Procedures I and II yielded 98 and 93% recoveries, respectively, from experiments performed either in vivo or in vitro. 4. Concentrations of labeled phenytoin found in brain, cerebellum, liver and kidney from the first to the fifth hour were 7.7, 7.8, 5.2, 4.0 and 2.2% (I) and 10.6, 8.5, 7.2, 4.0 and 2.8% (II) of the amount injected, correspondingly. 5. Concentrations of phenytoin in cerebellum were greater by a statistically significant margin than were those in other tissue at the third hour following the time of injection of radioactive phenytoin but liver and kidney concentrations were greater than cerebellum uptake at the fourth and fifth hour. 6. Brain showed the lowest incorporation of phenytoin throughout five hours.