Phenytoin increases 65zinc absorption in the rat.

A single oral dose of 65Zn was given to groups of rats, 6 or 7 in each, which were started on phenytoin. The drug was given in daily doses of 10, 50, and 100 mg for 10 days. The retention of 65Zn was followed by a whole body counter, and the net absorption of 65Zn was calculated. All phenytoin doses studied were found to increase zinc absorption significantly.