Raloxifene (RLX), a biopharmaceutical classification system (BCS) class II drug, is a selective estrogen receptor modulator (SERM) having an estrogenic effect on the bone and an antiestrogenic effect on the endometrium and breast. Low solubility, high permeability, high metabolism, and low bioavailability are the characteristics of raloxifene. Although 60% is absorbed orally, raloxifene shows extremely poor bioavailability (2%) owing to its low solubility and extensive (>90%) intestinal/hepatic first-pass metabolism. Hence, it becomes important to increase the solubility of raloxifene to enhance its bioavailability. In this study, raloxifene nanostructured lipid carriers (RNLCs) were prepared using the melt dispersion ultrasonication method. The prepared RNLCs were characterized, and the in vitro studies were carried out in the human epithelial breast cancer cell line (MCF-7). The RNLCs had a size of 114.8 ± 0.98 nm and a zeta potential of +9.21 ± 0.58 mV. Transmission electron microscopy (TEM) images showed particle size ranging from 65 to 120 nm. With an entrapment efficiency of 75.04% ± 2.75%, the RNLCs showed sustained release over 7 days compared with the raloxifene drug solution. The prepared RNLCs were successfully taken up by the MCF-7 cells in a time-dependent manner, and the RNLCs showed increased cell cytotoxicity compared with the raloxifene drug. Using the parallel artificial membrane permeability assay (PAMPA), the permeability rate for raloxifene solution was calculated to be 8 × 10-6 cm/s, and for the RNLCs, it was calculated to be 17.8 × 10-6 cm/s. Hence, from the permeability rate calculated, we could conclude that raloxifene, when formulated as nanostructured lipid carriers, showed increased permeability. Overall, the prepared RNLCs were found to be superior to the raloxifene drug as such.
Keywords: bioavailability; cytotoxicity; design raloxifene; drug; membrane; nanotechnology; permeability; solubility; sustained release.