Oral Bioactive Self-Nanoemulsifying Drug Delivery Systems of Remdesivir and Baricitinib: A Paradigmatic Case of Drug Repositioning for Cancer Management

Oral anticancer therapy mostly faces the challenges of low aqueous solubility, poor and irregular absorption from the gastrointestinal tract, food-influenced absorption, high first-pass metabolism, non-targeted delivery, and severe systemic and local adverse effects. Interest has been growing in bioactive self-nanoemulsifying drug delivery systems (bio-SNEDDSs) using lipid-based excipients within nanomedicine. This study aimed to develop novel bio-SNEDDS to deliver antiviral remdesivir and baricitinib for the treatment of breast and lung cancers. Pure natural oils used in bio-SNEDDS were analyzed using GC-MS to examine bioactive constituents. The initial evaluation of bio-SNEDDSs were performed based on self-emulsification assessment, particle size analysis, zeta potential, viscosity measurement, and transmission electron microscopy (TEM). The single and combined anticancer effects of remdesivir and baricitinib in different bio-SNEDDS formulations were investigated in MDA-MB-231 (breast cancer) and A549 (lung cancer) cell lines. The results from the GC-MS analysis of bioactive oils BSO and FSO showed pharmacologically active constituents, such as thymoquinone, isoborneol, paeonol and p-cymenene, and squalene, respectively. The representative F5 bio-SNEDDSs showed relatively uniform, nanosized (247 nm) droplet along with acceptable zeta potential values (+29 mV). The viscosity of the F5 bio-SNEDDS was recorded within 0.69 Cp. The TEM suggested uniform spherical droplets upon aqueous dispersions. Drug-free, remdesivir and baricitinib-loaded bio-SNEDDSs (combined) showed superior anticancer effects with IC50 value that ranged from 1.9–4.2 µg/mL (for breast cancer), 2.4–5.8 µg/mL (for lung cancer), and 3.05–5.44 µg/mL (human fibroblasts cell line). In conclusion, the representative F5 bio-SNEDDS could be a promising candidate for improving the anticancer effect of remdesivir and baricitinib along with their existing antiviral performance in combined dosage form.