Physical and chemical properties and percutaneous permeation of capsaicin / 中国药学杂志

ABSTRACT

OBJECTIVE: To study the physical and chemical properties and transdermal delivery characteristics oi capsaicin. METHODS: Equilibrium solubility method, ultraviolet spectrophotometry, bottle-shaking method, differential scanning ealorimetry (DSC) and in vitro diffusion cell method were used to determine the apparent solubility, dissociation constant, apparent oil/water partition coefficient, melting point and percutaneous penetration of capsaicin, respectively. And the permeation characteristics were evaluated by lag time method. RESULTS: Capsaicin was slightly dissolved in water, and the apparent solubility was (22.85 ± 0.06) mg · L-1. It was a weak base with a dissociation constant of (10.25 ± 0.11). The apparent oil/water partition coefficient of capsaicin changed with the pH value, and increased when pH was greater than 8. Its melting point was 60.20°C. The residence time(ttag) was (2.437 ± 0.273) h, the permeability coefficient (P) (7.012 ± 0.341) × 10-2cm · h-1, and the percutaneous penetration rate (Js) (4.647 ± 0.226) μg · cm-2 · h-1. CONCLUSION: Capsaicin possesses appropriate physical and chemical properties for percutaneous penetration and exhibits excellent percutaneous penetration.