Sucrose ester stabilized solid lipid nanoparticles and nanostructured lipid carriers: I. Effect of formulation variables on the physicochemical properties, drug release and stability of clotrimazole-loaded nanoparticles

The objective of this study was to develop and evaluate solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) utilizing sucrose ester as a stabilizer/emulsifier for the controlled release of drug/active. Both SLNs and NLCs were prepared using different sugar esters to screen out the most suitable stabilizer. Clotrimazole was used as a model active/drug. The effect of different formulation variables on the particle size, polydispersity index and drug encapsulation efficiency of SLNs and NLCs was evaluated and compared. SLNs and NLCs were physicochemically characterized and compared using Cryo-SEM, DSC and XRD. Furthermore, a drug release study of SLNs and NLCs was conducted. Finally, physicochemical stability (size, PI, ZP, EE) of the SLNs and NLCs was checked at 25 +/- 2 degrees C and at 2-8 degrees C. Among the sucrose esters, D-1216 was found to be most suitable for both SLNs and NLCs. Formulation variables exhibited a significant impact on size, PI and EE of the nanoparticles. SLNs with similar to 120 nm size, similar to 0.23 PI, similar to I26I mV ZP, similar to 87% EE and NLCs with similar to 160 nm size, 0.15 PI, similar to I26I mV ZP, similar to 88% EE were produced. Cryo-SEM revealed spherical particles with a smooth surface but did not exhibit any difference in surface morphology between SLNs and NLCs. DSC and XRD results demonstrated the disappearance of clotrimazole peak(s) in drug-loaded SLNs and NLCs. Faster drug release was observed from SLNs than NLCs. NLCs were found to be more stable than SLNs in terms of size, PI, EE and drug release. The results indicated that both SLNs and NLCs stabilized with sucrose ester D-1216 can be used as controlled release carriers although NLCs have an edge over SLNs.