Venlafaxine is freely soluble In water and administered orally as hydrochloride salt In two to three divided doses. In the present investigation different release retarding matrices have been evaluated for sustained release of venlafaxine hydrochloride (VH) from the formulated tablets.
Sustained release matrix tablets were formulated using different hydrophilic, hydrophobic and waxy materials as matrix formers. Tableting was done by pre-compression, direct compression and hot melt granulation depending on the type of matrix material used and evaluated for different tests. The formulated tablets were compared with commercial venlafaxine products. In vitro drug dissolution profiles were fitted In different mathematical models to elucidate the release mechanism.
Dissolution data showed that commercial formulations Venlor XR(®) and Venfax PR(®) released the entire drug withIn 8 h where as the formulated tablets with hydroxypropylmethylcellulose (HPMC) and cetyl alcohol as matrix formers provided sustained release of drug for 14-15 h. The release was found to follow Hixson Crowel and Higuchi kinetics for HPMC and cetyl alcohol tablets, respectively.
The developed matrix tablet formulations with HPMC and cetyl alcohol provided sustained release profiles for prolonged periods than commercial formulations.