title: Three-way, three-period, crossover bioequivalence study of single oral dose of three brands of 300 mg phenytoin sodium tablets marketed in India, on healthy Indian human volunteers.
abstract: OBJECTIVE
  To compare the bioavailability of two brands of phenytoin sodium tablets available in the Indian market using Eptoin™ as the reference.
  
  
  METHODS
  A randomized, assessor-blind, three-way crossover design study was carried out over a period of 6 months after approval from the Institutional Review Board (IRB). Twenty-two healthy male participants received a single oral 300 mg oral tablet of either of the formulations with a 2-week washout. Blood samples were collected predose and at regular intervals postdose. Plasma phenytoin levels were estimated by high-performance liquid chromatography. Calculation of Cmax, AUC0-t, and AUC0-∞ was done by the linear trapezoidal rule and 90-110% margin (90% confidence interval (CI)) was used to assess bioequivalence.
  
  
  RESULTS
  Twenty volunteers completed the study. It was seen that the log-transformed values of Cmax, AUC0-t, and AUC0-∞ of the test formulations were not within the specified limits.
  
  
  CONCLUSIONS
  Bioinequivalence of available phenytoin brands indicates that switching brands could lead to variations in blood concentrations and thus impact safety and efficacy. If a brand switch is done for any reason, stringent drug-level monitoring is advised.
authors.affiliation: Department of Clinical Pharmacology, Seth G S Medical College and KEM Hospital, Mumbai, India.
authors.forename: Maulik S
authors.initials: MS
authors.lastname: Doshi
authors.forename: Anuja A
authors.initials: AA
authors.lastname: Naik
authors.forename: Mohit R
authors.initials: MR
authors.lastname: Mehta
authors.forename: Nithya J
authors.initials: NJ
authors.lastname: Gogtay
authors.forename: Urmila M
authors.initials: UM
authors.lastname: Thatte
authors.forename: Mala D
authors.initials: MD
authors.lastname: Menon
keywords: Bioequivalence; bioavailability; healthy volunteer; phenytoin sodium