Abstract
<title>Abstract</title> <p>Background Topical formulations containing cannabis in South Africa must comply with the legal standards of Schedule 0 products with a low CBD content and negligible amounts of THC. A selection of commercially available South African CBD and extemporaneously prepared topicals were evaluated and compared for formulation differences that may affect CBD stability. Methods The stability of CBD in the different topical formulations was assessed under in-use conditions of light exposure and elevated temperature. The physical properties of a selection of commercial and extemporaneously prepared CBD topical forms were characterized. The extemporaneous formulations were oil-in-water (o/w) emulsions with product attributes similar to those of commercially available aqueous cream. CBD content was determined using a validated HPLC method. Results Structural components of the emulsions resulted in high viscosity, particularly for the Pickering emulsion. The spreadability of the topical products was affected by both temperature and formulation type. CBD degraded on exposure to light and increased temperature. The commercially available CBD gel had significantly better stability than other products. Tissue oil exhibited a significant decrease in CBD content, which may lead to poor consumer acceptability. The Pickering emulsion may exhibit better stability of CBD; however, the spreadability at 37°C was lower than that of the other extemporaneously prepared o/w emulsion formulations. Conclusions Storage temperatures and light exposure significantly increase CBD degradation in formulations with fewer antioxidants and lower viscosity among the South African commercial products tested. Excipients such as Aerosil® R974 may be used to produce a Pickering emulsion for a high viscosity o/w emulsion for a CBD topical formulation that has improved CBD stability at 37°C.</p>