McColl K E, Moore M R, Thompson G G, Goldberg A
Br J Clin Pharmacol. 1980 Apr;9(4):327-31. doi: 10.1111/j.1365-2125.1980.tb01058.x.
1 In rats daily phenytoin (DPH) administration resulted in an increase in hepatic cytochrome P450 content. The rise in cytochrome P450 was associated with a temporary increase in the acitvity of hepatic delta-aminolaevulinic acid (ALA) synthase. 2 In patients newly commenced on DPH anticonvulsant therapy the activity of ALA synthase in peripheral leucocytes showed a marked temporary increase during the first 10 days of therapy. 3 These findings suggest that DPH induces a haem-requiring eenzyme system in peripheral leucocytes as well as in hepatic tissue.