Abstract

Effect of Hydroxylpropylated beta Cyclodextrin and pH on Solubility of Telmisartan

Author(s): B. D. Shewale, P. O. Patil, P. K. Deshmukh and R. A. Fursule

The present study was undertaken to examine the effect of pH and concentration of hydroxypropylated-0-cyclodextrin (HP-0-CD) on the solubility of telmisartan as it shows the pH dependent solubility. The equilibrium solubility of telmisartan in a series of solutions of varying pH (from 1.2 to 11) was determined and compared with the equilibrium solubility of telmisartan in the presence of 20% HP-0-CD at same pH values. It was observed that solubility of protonated form is more than the neutral molecule. HP-0-CD resulted in increased solubility at all the pH. But inclusion in the cavity of HP-0-CD might depend upon charge state of the molecule. So it can be concluded that solubility of telmisartan can be increased either by the addition of HP-0-CD or by adding pH lowering agents. If both these methods are to be used together, pH should be selected carefully.