Abstract

In the present work, a naturally occurring smectite group clay mineral, montmorillonite, (Mt) has been explored as a vehicle for delivery of
an antidepressant drug Venlafaxine hydrochloride, VF. The effect of pH of the drug solution, time and initial drug concentration on drug
loading capacity of Mt has been studied. The adsorption isotherm was fitted by the Langmuir model and follows the pseudo-second-order
kinetics. The synthesized Mt-VF complexes were characterized by XRD, FTIR, TGA, DSC etc. VF was found to be intercalated in the Mt
layers. The release profile of the VF and Mt-VF complex in simulated gastric and intestinal fluids has been discussed. The release
behaviour of VF from Mt-VF complexes appears to be sustained/extended for a period of 12 h and reaches upto 52 % in simulated gastric
fluid and is stable in intestinal fluid where as pure VF completely gets released in 5.5 h and 3.5 h in simulated gastric and intestinal fluid
respectively. Out of all kinetic models used to elucidate the drug release mechanism, the best fitting was observed for first order model. On
the basis of present studies it can be stated that the synthesized Mt-VF complexes have the potential for developing in to a sustained release
formulation for oral drug delivery of an anti-depressant drug VF. This shows a path which can reduce doses substantially from 4 times in 24
h to twice in 24 h.

Key words: Venlafaxine hydrochloride; montmorillonite; oral drug delivery