Effect of major components of Maijunan tablets on the transport of hydrochlorothiazide in Caco-2 cell monolayer model

To study the effects of major components of Maijunan tablets, puerarin (Pue) and rhynchophylline (Rhy) on the transport of hydrochlorothiazide (Hct) Caco-2 cell monolayer model, the transport parameters of Hct, such as apparent permeability coefficient (P_{app (B→A)} and P_{app (A→B)}) and the ratio of P_{app (B→A)} versus P_{app (A→B)}, were studied and compared when Hct was used solely and co-used with Pue and/or Rhy.  The effects of drug concentrations, conveying times, P-glyprotein (P-gp) inhibitor verapamil and conveying Liq pH values on the transport of Hct in the above conditions were also investigated.  The results indicated that the absorption of Hct in Caco-2 cell monolayer model could be a carrier-mediated active transport, along with the excretion action  mediated by P-gp.  Pue can decrease the excretion action of Hct mediated by P-gp, and Rhy had no significant effect on the transport of Hct.  The co-use of Hct, Pue and Rhy enhanced the absorption of Hct.  Meanwhile, conveying Liq pH value had significant influence on the transport of Hct.  The absorption of Hct at pH 6.0 was higher than that at pH 7.4.