Ameliorating the antiparasitic activity of the multifaceted drug ivermectin through a polymer nanocapsule formulation

Ivermectin (IVM) is a potent antiparasitic widely used in human and veterinary medicine. However, the low oral bioavailability of IVM restricts its therapeutic potential in many parasitic infections, highlighting the need for novel formulation approaches. In this study, poly(ε-caprolactone) (PCL) nanocapsules containing IVM were successfully developed using the nanoprecipitation method. Pumpkin seed oil (PSO) was used as an oily core in the developed nanocapsules. Previously, PSO was chemically analyzed by headspace solid-phase microextraction coupled to gas chromatography/mass spectrometry (HS-SPME/GC-MS). The solubility of IVM in PSO was found to be 4266.5 ± 38.6 μg/mL. In addition, the partition coefficient of IVM in PSO/water presented a logP of 2.44. A number of nanocapsule batches were produced by factorial design resulting in an optimized formulation. Negatively charged nanocapsules measuring around 400 nm demonstrated unimodal size distribution, and presented regular spherical morphology under transmission electron microscopy. High encapsulation efficiency (98-100%) was determined by HPLC. IVM-loaded capsules were found to be stable in nanosuspensions at 4 °C and 25 °C, with no significant variations in particle size observed over a period of 150 days. Nanoencapsulated IVM (0.3 mM) presented reduced toxicity to J774 macrophages and L929 fibroblasts compared to free IVM. Moreover, IVM-loaded nanocapsules also demonstrated enhanced in vitro anthelmintic activity against Strongyloides venezuelensis in comparison to free IVM. Collectively, the present findings demonstrate the promising potential of PCL-PSO nanocapsules to improve the antiparasitic effects exerted by IVM.