Topical delivery of diclofenac into and across equine skin from a novel liquid diclofenac epolamine formulation.

This research study aimed to examine the effectiveness of a new diclofenac epolamine (DIC-EP) formulation for delivering the drug diclofenac into and across the skin of horses, compared to existing treatments. The results indicate that the new DIC-EP formulation delivers diclofenac significantly more effectively and this delivery seems to be affected by the age of the horse.

Research Methodology

• The research involved in vitro (outside the living organism) investigation using Franz diffusion cells. This is a standard technique used to measure the rate of drug delivery across a barrier such as skin.
• Skin samples were harvested from the lower legs of Freiberger geldings (a breed of horse) immediately after slaughter. The skin was sliced to approximately 2mm thickness.
• The samples were separated into two groups based on the age of the horses from which the skin was taken: Group 1 consisted of 1-year-olds, and Group 2 comprised of horses aged 6 to 8 years.

Research Findings

• The study found that the cumulative permeation of diclofenac after 24 hours using the current standard treatment (a 1% aqueous solution of diclofenac sodium) was relatively low.
• The study also found that diclofenac permeation from the newly developed DIC-EP formulation was significantly higher than both the standard aqueous solution and another existing treatment known as Surpass (a 1% diclofenac sodium liposomal cream).
• Interestingly, the delivery of diclofenac by DIC-EP appeared to show an age-dependent effect, meaning its effectiveness varied based on the age of the horse.

Implications of the Study

• The mathematical modelling used in the study showed that the DIC-EP formulation markedly increased diclofenac partitioning into the skin.
• Higher skin deposition of diclofenac was also observed with DIC-EP, indicating that more of the drug remained in the skin to exert its effects.
• The preliminary results suggest that the DIC-EP formulation might be more effective in treating inflammatory conditions in horses. However, more extensive research will be needed to confirm these findings.