In vivo distribution of carbon-11 phenytoin and its major metabolite, and their use in scintigraphic imaging.

Curie quantities (0.3--1.5 Ci) of H11CN were used in the synthesis of C-11-tagged phenytoin (C-11.DPH) and 5-(p-hydroxyphenyl)-5-phenylhydantoin (C-11.HPPH), using a modified Bücherer-Bergs reaction. The H11CN was produced from a mixture of 95% nitrogen and 5% hydrogen by a 45-min bombardment with 10-MeV protons at 10 muA. Following i.v. infusions of C-11 DPH (13.7 mg/kg at a rate of 29 mg/min) into the left femoral vein of Rhesus monkeys, DPH shows persistent concentration in the brain and liver fields. Extravascular administration shows significant retention at the site of administration. Intravenous bolus injection of [11C]-HPPH into a Rhesus monkey, at a dose of 6.4 mg/kg, resulted in localization of this compound in the liver, gallbladder, urinary bladder, and intestinal fields. Loss of activity from the liver region, with appearance of this activity in the intestinal field, suggests that [11C]-HPPH is secreted into the intestine via the bile. Further investigation is needed to study the potential of [11C]-DPH as a brain-scanning agent and [11C]-HPPH as a possible cholescintigraphic agent.