Abstract:
This study was aimed to develop solid lipid nanoparticles (SLNs) as well as nanostructured lipid
carriers (NLCs) and evaluate their potential as carrier systems for topical delivery of benzocaine to improve the
drug entrapment efficiency and sustained release. SLNs and NLCs were prepared by high shear homogenization
followed by ultrasonication method, using different types of solid lipids such as glyceryl monostearate, stearic
acid and Compritol 888 ATO. Isopropyl myristate, as a liquid lipid in formulation of NLCs was used in different
ratios to study the influence of liquid lipid content on the particle size, entrapment efficiency and zeta potential
of the formulated benzocaine loaded lipid nanoparticles. The results indicated that entrapment efficiency and
particle size depend on the concentration and the lipid mixture employed. The selected NLCs (NLC6) was
further incorporated in 5% carboxymethyl cellulose (CMC) hydrogel and then characterized for appearance,
pH and in-vitro drug release. The prepared SLNs and NLCs possessed an average particle size of 214 – 440
nm, zeta potential of (-19.6) to (-25.9) mV and 55.65 – 94.62 % entrapment efficiency. The prepared NCL6
loaded hydrogel showed a smooth texture hydrogel free from any agglomeration of lipid nanoparticles with pH
value of 6.10.The release studies of the investigated NLC6 showed an initial fast release that lasted for 0–1 hr,
followed by a sustained release for 8 hrs.These promising findings encourage the potential use of benzocaine
loaded lipid nanoparticles for future topical application improving its therapeutic efficacy for topical treatment
of pain.