Surface modified solid lipid microparticles based on homolipids and Softisan® 142: preliminary characterization

Abstract

Objective To preliminarily investigate three different lipid matrices consisting of two natural homolipids from Capra hircus (goat fat) and Bovine Spp. (tallow fat) and one semi-synthetic lipid (Softisan® 142) separately structured with Phospholipon® 90G (P90G) as potential delivery systems for poorly water soluble drugs. Methods The structured lipid matrices were characterized by differential scanning calorimetry (DSC) and employed to prepare solid lipid microparticles (SLMs) by the melt homogenization method using gradient concentrations of polysorbate 80 and at different emulsification times of 2, 5 and 10 min using a Silverson mixer. The SLMs were analyzed for morphology and particle size, thermal properties, stability studies and determination of injectability. Results The results showed that SLM production was optimum at 5 % of lipid matrices, 1.5 % of polysorbate 80 and emulsification time of 5 min. Increase in polysorbate 80 concentrations decreased the particle size of the SLMs. The SLMs were well formed, spherical, smooth and non-porous with particle sizes in the ranges of (13.90 ± 2.10) μm - (0.09 ± 0.01) μm for SLMs produced from the structured - tallow fat; (13.40 ± 1.30) μm - (0.10 ± 0.01) μm for the structured - goat fat and (13.40±2.00) μm - (2.10± 1.00)μm for the structured Softisan® 142 lipid matrices. DSC traces showed that Softisan® 142 was the most crystalline of all three bulk matrices due to its high enthalpy (−7.962 mW/mg) while tallow fat was the least (−5.067 mW/mg) but addition of P90G to the matrices lowered their enthalpies mostly in the structured goat fat matrices. The SLMs when stored at 4-6 ° were most stable and syringeable with 27 G needle. Conclusions This suggests that structured goat fat matrices with the enthalpy of −2.813 mW/mg will mostly favour drug loading of some poorly soluble drugs more than tallow fat (−4.892 mW/mg) and Softisan® 142 (−5.501 mW/mg).