Selection of cryoprotective agent for freeze drying of valsartan solid lipid nanoparticles

The aim of the present study was to select the cryoprotective agent for valsartan solid lipidnanoparticles. The cryoprotective agents were mixed with prepared nanoemulsion and lyophilized for 24h. The cryoprotective agent and its concentration were selected on the basis of particle size, polydispersity index and zeta potential. The stability of prepared nanoparticles (with and without cryoprotective agents)was also determined in respect of particle size and polydispersity index. The cryoprotective agents showed their effect in the following order: mannitol > lactose > sorbitol > maltose > glucose > sucrose > PVP > fructose > starch > dextrose. The particle size, PDI and zeta potential of the nanoformulations containing 10 % mannitol was found to be 403 nm, 0.39 and -19.27 mV, respectively. Six months accelerated stabilitystudy data does not show any significant effect (at p > 005) of temperature on the lyophilized nanoformulations.The present study concludes that the mannitol is a very good cryoprotective agent to retain thesmall particle size and least PDI value of valsartan nanoformulations even at temperatures of 30 and 40°C.