Abstract:
The aim of the present investigation was to develop a microemulsion based hydrogel
(MBH) formulation for topical delivery with an objective to increase the solubility and
skin permeability of Nitrofurazone which is an antibacterial agent. The study was also
undertaken to overcome the drawbacks associated with oral drug delivery systems such
as poor solubility of drugs, drug degradation in gastric environment, hepatic first pass
metabolism and gastrointestinal irritation. On the basis of solubility study, Isopropyl
myristate, tween 80 an PEG 400 were selected as oil, surfactant and co-surfactant
respectively for preparation of microemulsion. Pseudoternary phase diagrams were
constructed at various tween 80 and PEG 400 ratios. The 3:1 ratio represented greater
area of microemulsification. Hence, it was selected for preparation of microemulsion.
The prepared microemulsion was optimized on the basis of droplet size, zeta potential,
drug release . The optimized microemulsion was further evaluated for % transmittance,
dilutability, pH, viscosity, conductivity, drug content and stability study. The HPMC
(Hydroxy Propyl Methyl Cellulose) K100M (2%) was slowly mixed with optimized
microemulsion under stirring for the preparation of MBH. The developed MBH
contained Nitrofurazone (0.2%, 2 mg/gm), Iso propyl myristate (6.25%w/w), tween 80 and PEG 400 (55%w/w, 3:1), Water (38.75%w/w) and HPMC K100M (2%). The
optimized MBH was evaluated for viscosity, spreadability, drug content, skin irritancy
and skin permeability. The mechanism of drug release from MBH was observed to follow
zero order kinetics on the basis of R2 value (Regression Coefficient) of various
mathematical kinetic models.
The antibacterial activity of MBH was compared with marketed Nitrofurazone cream and
it was found that the zone of inhibition for MBH was found to be comparable with
marketed cream. Thus, the MBH was successfully formulated for topical delivery to treat
bacterial skin infections.
