Spray-Dried Powder Containing Cannabigerol: A New Extemporaneous Emulgel for Topical Administration

Abstract

Cannabigerol (CBG), a cannabinoid from Cannabis sativa L., recently attracted noteworthy attention for its dermatological applications, mainly due to its anti-inflammatory, antioxidant, and antimicrobial effectiveness similar to those of cannabidiol (CBD). In this work, based on results from studies of in vitro permeation through biomimetic membranes performed with CBG and CBD in the presence and in the absence of a randomly substituted methyl-β-cyclodextrin (MβCD), a new CBG extemporaneous emulgel (oil-in-gel emulsion) formulation was developed by spray-drying. The powder (SDE) can be easily reconstituted with purified water, leading to a product with chemical-physical and technological characteristics that are comparable to those of the starting emulgels (E). Thermogravimetric analysis (TGA), attenuated total reflection-Fourier transformed infrared spectroscopy (ATR-FTIR), x-ray powder diffraction (XRPD), and high-performance liquid chromatography (HPLC) analyses demonstrated that the spray-drying treatment did not alter the chemical properties of CBG. This product can represent a metered-dosage form for the localized treatment of cutaneous afflictions such as acne and psoriasis.

Keywords: cannabidiol; cannabigerol; extemporaneous emulgels; methyl-β-cyclodextrin; re-dispersible powders; spray-drying.

Figure 1

Structure of (A) CBD and (B) CBG.

Figure 2

Thermogravimetric profiles of (A) CBD, pmCBD, knCBD, and MβCD and (B) CBG, pmCBD, knCBG, and MβCD.

Figure 3

(A) ATR-FTIR spectra of CBD (a), MβCD (b), pmCBD (c), and knCBD (d). (B) CBD ATR-FTIR spectrum (a) and different spectra obtained after subtracting the MβCD spectrum from the pmCBD spectrum (b) or knCBD spectrum (c). The most significant modifications of the CBD spectrum are marked with asterisks (*).

Figure 4

ATR-FTIR spectra of (A) CBG (a), MβCD (b), of pmCBG (c), and knCBG (d) and (B) CBG (a) and different spectra obtained after subtracting the MβCD spectrum from the pmCBG spectrum (b) or knCBG spectrum (c). The most significant modifications of the CBG spectrum are marked with asterisks (*).

Figure 5

“Retained” and “permeated” percentages of CBs calculated on the “total diffused” amounts from the cannabinoid-based solutions. Different lowercase letters correspond to significant differences between the “retained” percentages, while different uppercase letters highlight significant differences between the ”permeated” percentages.

Figure 6

Permeation profiles of CBs from the solutions of CBs and CBs-MβCDsol. The reported values are calculated with respect to the loaded amounts of cannabinoids in the donor compartment at the beginning of the experiments.

Figure 7

Starting emulgel (Ed), corresponding spray-dried powder (SDEd), and emulgel after reconstitution (Ed_R) (from left to right).

Figure 8

Up curves and down curves of (A) Ea (black-continuous lines) and Ea_R (red-dotted lines) and (B) Ed (blue-continuous lines) and Ed_R (orange-dotted lines).

Figure 9

Thermogravimetric profiles of (A) single components of emulgels and (B) spray-dried powders.

Figure 10

(A) ATR-FTIR spectra of single components of the emulgels and spray-dried powders (SDEa ÷ SDEd). (B) ATR-IR spectrum of CBG (a) and different spectra obtained after subtracting the SDEa spectrum from the SDEc spectrum (b) or the SDEb spectrum from the SDEd spectrum (c). The signal at 1518 cm⁻¹ uniquely assigned to CBG is marked with an red asterisk (*).

Figure 11

XRPD patterns of single components of emulgels and spray-dried powders.