Percutaneous absorption of capsaicin and its derivatives

Nonivamide (NVA), sodium nonivamide acetate (SNA) and sodium nonivamide propionate (SNP) are analogues of Capsaicin (CAP). The structure and pungent property of NVA are similar to CAP. The solubilities of SNA in different pH value buffer solution were higher than that of NVA and CAP. For the NVA and SNA, the n-octanol/buffer partition coefficients decreased with increasing pH value. The fluxes of CAP and its analogues were determined using excised rat skin and the effect of pH was also investigated. The flux of NVA and SNA mixture was higher than individually NVA or SNA, and the ratio of 70:30 was a better choice. Sodium lauryl sulfate (SLS), an anionic surfactant, had significant effect on SNA skin permeation.