Dear Asif Mahmood

if lovastatin completely entrapped in your designed hydrogels, by one of the following methods you can exchange DMSO with a suitable buffer but you should consider the final solubility of DDS and lovastatin.

1-Centrifuge filter tubes

2- Dialysis

3- Millipore filter

if lovastatin has a leaky form in your designed hydrogels the following methods may help you

1-Rotary evaporator

2-Freeze drying

First tell me about water solubility of your finished product...say if it is water insoluble then you can remove the DMSO by washing with water...

Finished product is Hydrogel that is water swellable not soluble. It will only swell at pH 7.4