Simple and multiple emulsions have a wide range of
pharmaceutical applications. Therefore, the stabilization of such
emulsions is a challenge to ensure a stable formulation along the
period of storage, usage and at the same time to conserve the
efficacy of the incorporated medicament. Simple o/w and multiple
w/o/w emulsions were prepared using castor and paraffin oils as
oil phases and stabilized solely by silica nanoparticles of wellcontrolled
surface properties. Two non-steroidal ant-inflammatory
drugs, namely flurbiprofen and diclofenac sodium were
incorporated in the stabilized simple and multiple emulsions,
respectively. The stability of emulsions and the in vitro release of
the drugs from the prepared emulsions were studied. In addition,
the anti-inflammatory activity of the drugs from these liquid
formulations was assessed using carageenan-induced hindpaw
edema in rats. The results indicated that the prepared liquid
emulsions, which stabilized with silica nanoparticles, were highly
stable. The in vitro release of flurbiprofen and diclofenac sodium
from these simple and multiple emulsions showed higher rates
compared with those preapred from paraffin oil due to their lower
viscosities. The results revealed also that the percentage of oil has
a pronounced effect on the in vitro release rates of the drugs from
the emulsions. Furthermore, topical flurbiprofen and diclofenac
sodium emulsions exhibited a potent local anti-inflammatory
activity compared with the orally adminstered drugs in the
suspension form and this activity reached its peak (57-84%) 3 hrs
after carrageenan injection and persisted for 5 hrs, the period of
study.