| Summary: | 碩士 === 高雄醫學大學 === 藥學研究所 === 88 === The in vitro permeation of three diclofenac salts - diclofenac sodium (DFS), diclofenac potassium (DFP) and diclofenac diethylammonium (DFD), - across skin by both passive and iontophoretic transport were investigated. Various skin types were used as the barriers to elucidate the mechanism controlling transdermal delivery of diclofenac salts. Also, a series of physicochemical and electrical variables that might affect iontophoretic permeation of diclofenac salts was studied.
The importance of the intercellular (paracellular) route for both DFS and DFP in passive permeation was elucidated. The transappendageal (shunt) route constitutes the important permeation pathway for DFS but not for DFP. The route and mechanism for transdermal iontophoresis of DFD across the skin was somewhat different to that of the other salts. Hair follicles may be more important pathways for DFD than for DFS and DFP under iontophoresis, while the intercellular lipid pathway showed the opposite result. Combination of iontophoresis and a penetration enhancer, cardamom oil, did not show a synergistic effect on diclofenac salts permeation. The results suggest that the transdermal mechanism and route of diclofenac salts via passive and iontophoretic transports can be affected by their counterions.
Application of 0.3 mA/cm2 current density significantly increased the transdermal flux of diclofenac salts as compared to the passive transport. The iontophoretic enhancement increased in the order of DFS>DFP>DFD. The permeability coefficient of diclofenac salts all decreased with increasing donor concentration during iontophoresis. The addition of buffer ions and salt ions such as NaCl, KCl and C4H12ClN reduced the permeation of diclofenac salts due to the competitive effect. However, this effect was lesser for DFD than for DFS and DFP. Comparing the various application modes of iontophoresis, the discontinuous on/off mode showed lower but more constant flux than continuous mode.
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