Formulation and Evaluation of bi-layered tablets of Divalproex sodium

Abstract

Divalproex sodium is considered as the most important antiepileptic
drug and widely used for treatment of epilepsy and bi-polar disorders
and prophylaxis of migraine. The present work has been done to
formulate bi-layered tablet of Divalproex sodium containing
immediate release layer and sustained release layer. The FTIR study
revealed that there was no interaction between drug and polymer and
combination can be safely prepared. Both layers were prepared by wet
granulation technique as poor flow property exhibited by pure drug. The
immediate release layer was formulated by using sodium starch
glycolate, croscarmellose sodium as super disintegrantsand evaluated
for physical parameters, disintegration time and in vitro drug
release.
The optimized immediate release layer (IF6) with highest in vitro release of 98.11 was selected for bilayered tablet formulation. HPMC K4M and HPMC K100M polymer used to retard the drug release
from sustained release layer in different proportion and combination and evaluated for physical
parameter along with in vitro drug release studies. The optimized sustained release layer (SF8) which
extends the Divalproex sodium release more than 18 hrs was selected. In vitro drug release studies were
performed using USP type II apparatus (paddle method) in 900 ml of phosphate buffer pH 6.8 at 100
rpm. Finally Bi-layered tablets were prepared by double compression of selected sustained release
layer and immediate release layer of Divalproex sodium. The tablets were evaluated for hardness,
thickness, weight variation, friability, drug content uniformity and in vitro drug release. All the physical
parameters were in acceptable limit of pharmacopeial specification. The stability studies, shown the bilayer tablet was stable at 400
C / 75% RH for a period of 3 months.