An investigation on parameters affecting the optimization of testosterone enanthate loaded solid nanoparticles for enhanced transdermal delivery

The current research aimed to formulate and optimize testosterone enanthate-loaded solid lipid nanoparticles (TE-SLNs) for the enhanced TE transdermal delivery. To this end, TE-SLNs were prepared using ultrasound-assisted emulsification technique and their properties and permeation across the excised rat skin were investigated. Evaluation of lipid type as well as the ratio and contents of surfactant mixtures resulted in a polydispersity index, particle size, drug loading, drug encapsulation efficiency, and zeta potential of 0.317?±?0.006, 87.66?±?1.52?nm, 21.61?±?0.45 %, 44.71?±?1.14 % and -23.06?±?0.50?mV, respectively. ATR-FTIR spectra of TE-SLNs exhibited the prominent functional groups of TE in the formulations, indicating a well-dispersion of TE in the lipid matrix without any chemical interaction with other components of the formulation. Differential scanning calorimetry (DSC) demonstrated that TE in SLNs is in an amorphous state. Transmission electron microscopy (TEM) confirmed that the prepared TE-SLNs have a stable size and maintained their sphericity. The results of TE permeation across the excised rat skin from SLNs displayed cumulative amounts of 110.61?±?17.7?µg/cm2, which is 3.2 fold improvement in TE permeation in comparison with the testosterone enanthate solution in oleic acid (p?