title: Comparison of the bioavailability of unequal doses of divalproex sodium extended-release formulation relative to the delayed-release formulation in healthy volunteers.
abstract: Valproate formulations, divalproex sodium extended-release (ER) and the traditional divalproex sodium delayed-release (DR) formulations, are not bioequivalent. This study evaluated if ER QD regimens with 14 and 20% higher daily doses were equivalent to the corresponding DR BID regimens with respect to exposure (AUC) while achieving lower maximum concentration (C(max)) and higher minimum concentration (C(min)) values. This was a Phase I, multiple-dose, fasting, randomized, open-label, crossover design study in healthy adult volunteers (n=36). The two crossover comparisons of unequal total daily doses were: 1000 mg ER versus 875 mg DR and 1500 mg ER versus 1250 mg DR. For each of 14 and 20% higher ER versus DR dose comparisons, the ER and DR regimens were equivalent with respect to AUC. Furthermore, the ER formulation achieved a lower C(max) central value and a higher C(min) mean than the corresponding values for the DR formulation. The mean peak-to-trough fluctuations of valproic acid plasma concentrations were 42-48% lower for the ER formulation compared with the DR. The higher ER doses were as well tolerated as DR, with a small number of adverse events that were non-serious in nature and mild in intensity. Therefore, increasing the once-daily ER dose 14-20% while converting from a total daily DR dose given twice-daily results in equivalent exposure with lower C(max) and higher C(min) values.
authors.affiliation: Abbott Laboratories, 100 Abbott Park Road, Dept. R4PK, Bldg. AP13A, Abbott Park, IL 60064-6104, USA. sandeep.dutta@abbott.com
authors.forename: Sandeep
authors.initials: S
authors.lastname: Dutta
authors.forename: Yiming
authors.initials: Y
authors.lastname: Zhang
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Selness
authors.forename: Lillian L
authors.initials: LL
authors.lastname: Lee
authors.forename: Laura A
authors.initials: LA
authors.lastname: Williams
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Sommerville
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D019540:Area Under Curve; D001682:Biological Availability; D002626:Chemistry, Pharmaceutical; D016001:Confidence Intervals; D018592:Cross-Over Studies; D003692:Delayed-Action Preparations / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014635:Valproic Acid / Q000008:administration & dosage* / Q000009:adverse effects / Q000097:blood* / Q000493:pharmacokinetics
chemical_list: D003692:Delayed-Action Preparations; D014635:Valproic Acid