Comparative drug elimination in man-diphenylhydantoin and amobarbital.
The concentration of 5,5-diphenylhydantoin (DPH) in serum was determined at selected time intervals in seven healthy male volunteers starting 10 h after an oral dose of 400 mg sodium DPH was given. The data were analyzed according to a one-compartment model assuming first-order kinetics. The mean serum half-life was  19.28 h +/- 5.87 (SD). A positive correlation coefficient (r=0.84, p less than 0.05) was found between the serum DPH half-life and the serum amobarbital half-life in the seven subjects. The urinary levels of free plus conjugated 5-(p-hydroxyphenyl)-5-phenyl-hydantoin were determined for 12 h periods over a minimum of two days following the 400 mg oral dose of sodium DPH. Subjects with a short DPH half-life tended to excrete in urine a greater amount of p-HPPH as compared to subjects with a long DPH half-life. In the case of one subject, the urinary excretion of p-HPPH plateaued five days after DPH administration and the apparent elimination half-life determined from the p-HPPH urinary excretion data was 19.16 h as compared to the value of 19.53 h calculated from the DPH serum levels.
D000328:Adult; D000654:Amobarbital / Q000097:blood*; D001711:Biotransformation; D006207:Half-Life; D006801:Humans; D006827:Hydantoins / Q000652:urine; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010672:Phenytoin / Q000097:blood*
D006827:Hydantoins; D010672:Phenytoin; D000654:Amobarbital