Effect of cimetidine on phenytoin serum levels.
Cimetidine, 300 mg p.o. four times a day, was administered for 5 days to nine epileptics who were stabilized while receiving phenytoin. Five patients had statistically significant increases in phenytoin serum levels, including two who became clinically toxic. One patient had a statistically significant decrease in phenytoin serum concentration. A relationship was not found between cimetidine levels and change in phenytoin serum levels. Cimetidine can cause significant changes in phenytoin serum levels which may be manifested clinically.
D002927:Cimetidine / Q000008:administration & dosage*; D004357:Drug Synergism; D004827:Epilepsy / Q000097:blood* / Q000188:drug therapy; D006146:Guanidines / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D010672:Phenytoin / Q000097:blood* / Q000627:therapeutic use
D006146:Guanidines; D010672:Phenytoin; D002927:Cimetidine