Formulation and in vitro skin penetration of a solid lipid nanoparticle gel containing coffea arabica extract

Objective: The extract of Coffea contains caffeine that could be used for its anticellulite activity. This study aimed to formulate a Coffea arabica grounds residue extract into a solid lipid nanoparticles (SLNs) gel dosage form and examine the physical stability and in vitro skin penetration of the formulation. Methods: Coffee grounds residue (CGR) extracts were made into three SLN formulations with different glycerin monostearate (GMS) concentrations of 1%, 2%, and 3%. The SLN F2 formulation was a gel created by high-pressure homogenization (HPH). The in vitro penetration assessed using Franz diffusion cells and the physical stability of the SLN extract gels was compared with those of the nonsense extract gel. Results: Formulation F2 with 2% GMS had a mean particle size (PS) of 60.3 nm, a polydispersity index (PDI) of 0.278, and zeta potential of -32±1.40. The PS for the SLN gel after HPH was 159 nm and the PDI was 0.211. Cycling and mechanical tests showed that the SLN gel was physically stable. The cumulative amount of caffeine penetrated in vitro was 5.55±0.08 for the CGR-SLN gel and 4.18±0.08 for the CGR gel. Conclusions: The amount of caffeine penetrated into rat skin was greater for the CGR-SLN gel than for the CGR gel.