Objective: This paper was to study absorption of neoandrographolide in human Caco-2 cell monolayer model. Method: Caco-2 cell monolayer model was applied to investigate the bidirectional transport of neoandrographolide. The effect of time

drug concentration

temperature and inhibitor on the absorption of neoandrographolide was observed. Drug concentration was measured by LC-MS-MS and the apparent permeability coefficients (Papp) was calculated. Result: No time or concentration saturation were observed for the transport of neoandrographolide across Caco-2 monolayers

PBA/PAB≈1.0. For the comparison of the temperature influence

the Papp [(2.02±0.31)×10-6 cm·s-1] at 37℃ was higher than the Papp at 4℃ [(5.97±0.11)×10-7 cm·s-1] and 25℃ [(9.17±0.50)×10-7cm·s-1](P<0.05). With the presence of iodoacetamide

the Papp was (4.79±0.42)×10-6

deffered significantly from the Papp [(1.28±0.69)×10-6] without iodoacetamide. Conclusion: The absorption of neoandrographolide in Caco-2 cell monolayers are passive diffusion and active transportation.