Codelivery of Paclitaxel and Cannabidiol in Lipid Nanoparticles Enhances Cytotoxicity against Melanoma Cells

Abstract

Although chemotherapy regimens are well-established in clinical practice, chemoresistance and adverse side effects pose significant obstacles in cancer treatment. Paclitaxel (PTX), a widely used chemotherapeutic agent, faces formulation challenges due to its poor solubility and permeability. Research suggests that the phytochemical Cannabidiol (CBD) holds potential not only in targeting cancer cells but also in alleviating pain and nausea, thereby improving the quality of life for cancer patients. However, CBD's clinical application is also limited by its poor solubility, low bioavailability, and susceptibility to oxidation. Nanostructured lipid carriers (NLCs) represent a promising drug delivery system for hydrophobic compounds like PTX and CBD and allow their coencapsulation. Nonetheless, achieving a stable formulation requires the identification of suitable preparation methods and excipients. The aim of this study was to develop and optimize an NLC formulation for the coencapsulation of PTX and CBD. Using factorial design, an optimized formulation was obtained with homogeneous particle sizes (200 nm), negative ZPs (-16.1 mV), a particle concentration of 10¹³ particles/mL, spherical morphology (TEM images), and a lipid core with low crystallinity (confirmed by XRD). To evaluate the therapeutic potential of the drug combination, cell viability assays were conducted on murine melanoma cells (B16-F10) at different exposure times (24 and 48 h). The NLC-CBD-PTX formulation significantly reduced cell viability in a time- and concentration-dependent manner, demonstrating at least 75% greater activity at 24 h compared to each drug individually, whether free (PTX, CBD) or encapsulated (NLC-PTX, NLC-CBD). This indicates a synergistic effect between CBD and PTX when coencapsulated, particularly at higher concentrations and shorter exposure times. In conclusion, an innovative pharmaceutical formulation coencapsulating PTX and CBD was validated, showing potential to enhance antitumor efficacy, overcome chemoresistance, reduce side effects, and broaden therapeutic applications. The resulting NLCs exhibited favorable physicochemical properties, supporting their suitability for various routes of administration.

1

Factorial design results for the NLC–CBD-PTX system: response surfaces for size (A), PDI (B), and ZP (C).

2

Physical stability in terms of size, PDI, and ZP of the nanoparticles of the optimized NLC (formulation 9) containing cannabidiol and paclitaxel under storage at room temperature for 60 days. ANOVA post hoc Tukey test: ns, nonsignificative.

3

X-ray diffractograms of pure myristyl myristate (MM), pure Pluronic F-68 (P68), pure paclitaxel (PTX), cannabidiol encapsulated in NLCs (NLC–CBD), paclitaxel encapsulated in NLCs (NLC-PTX), and the association of cannabidiol and paclitaxel in NLCs (NLC–CBD-PTX). NLC formulations were freeze-dried before analysis. All diffractograms are in the same scale.

4

TEM micrographs of NLC formulations without PTX (NLC–CBD, A, B) and with PTX (NLC–CBD-PTX, C, D). Magnifications: 18,500× (A, C) and 23,000× (B, D).

5

Release profile of paclitaxel (A) and cannabidiol (B) in TAXOL, cannabidiol oil (CBD), and paclitaxel/cannabidiol loaded in NLCs (NLC–CBD-PTX) measured in Franz cells at 37 °C (n = 3).

6

Cell viability (MTT assay) of melanoma strain (B16F10 cells) treated for 24 h (A, C) and 48 h (B, D) with cannabidiol oil (CBD) or encapsulated in NLC (NLC-CDB), paclitaxel commercial (TAXOL) or encapsulated in NLC (NLC-PTX), and the association of cannabidiol and paclitaxel in NLC (NLC–CBD-PTX). Results expressed as mean ± SD (n = 12). Statistical analysis by two-way ANOVA plus Tukey-Kramer post hoc. * p < 0.05; ** p < 0.01; *** p < 0.001, **** p < 0.0001.