Acute conduction velocity changes in guinea-pigs after administration of diphenylhydantoin

Motor nerve conduction velocity was measured after dosing guinea-pigs with 200-400 μmol/kg diphenylhydantoin (DPH) daily for three to four days. Conduction velocity fell by a mean value of 13% in animals that achieved plasma DPH levels over 200 μmol/l. There was no change in velocity with DPH levels below this value.