Abstract: AIM: To study the effects of N-acetyl-L-cysteine (NAC)on permeation and transport of insulin across the buccal TR146 cell culture model. METHODS: A human buccal epithelium model was established using TR146 cell line grown on Millicell culture plate inserts.The effects of NAC (1.25 %, 2.5 %, 5 %, 10 %)on permeation and transport of insulin across TR146 multilayer were studied.The apparent permeability coefficient (Papp)of insulin and the enhancement ratio (ER)of NAC were calculated, and the effects of NAC (1.25 %, 2.5 %, 5 %, 10 %) on TR146 cell activity were studied with MTT assay. RESULTS: 5 %, 10 % NAC significantly enhanced the permeation and transport of insulin across TR146 multilayer.Their Papp were 4.92 ±0.62 and 5.04 ± 0.52 (×10 ^-6 cm s, n =5) respectively, and ER were 5.22 ±0.88 and 6.05 ±0.18 respectively (n = 5), all of which were statistically higher than that of control group (P <0.05).The cell relative enzyme activity was significantly decreased, and those in the other groups had no significant defference compared with control group.CONCLUSION: 5 % NAC can greatly enhance the permeation and transport of insulin across TR146 multilayer, with little toxicity effects on the activity of TR146 cells.Therefore, NAC would be one safe and effective permeation enhancer for insulin transport.

Key words: TR146, N-acetyl-L-cysteine, insulin, permeation and transport