Study On Intestinal Absorption Characteristics Of Camptothecin Derivative CZ48

CZ48,a camptothecin(CPT)derivative,is designed and synthesized to protect CPT active structure,the lactone ring and reduce its toxicity.It has shown good anti-tumor activity and has attracted wide attention.Micronized CZ48(MCZ48),a CZ48 formulation is undertaken Phase I clinical trial in US.The intestinal absorption characteristics of CZ48 and MCZ48 were studied via in site intestinal perfusion model and Caco-2 cell model.(1)A HPLC method for the determination of CZ48 in Caco-2 cell transport medium and in situ rat intestinal perfusion liquid was established.CZ44 was used as internal standard,and Thermo Hypersil Gold C18 column was used to separate the analytes by binary mobile phase gradient elution.The mobile phase A was water containing 0.1%acetic acid,mobile phase B was acetonitrile,the flow rate was 1.2 mL/min,the excitation wavelength(Ex)was 380 nm,the emission wavelength(Em)was 418 nm,the injection volume was 40?L,and the running time was 20 min.The method is simple,rapid,accurate,and was successfully applied to the study of intestinal absorption characteristics of CZ48 and MCZ48.(2)Caco-2 cell model was established to investigate the bidirectional transport of CZ48 at different concentrations(250,500,1000 nM).The effects of pH,temperature,P-gp inhibitor verapamil,MRP inhibitor indomethacin,phosphatase inhibitor sodium vanadate,and bypass transport enhancer EDTA on the transport of CZ48 were investigated.The bidirectional transport of MCZ48(250,500,1000 nM)at different concentrations was also tested.The results showed that the Papp value of CZ48 AP?BL direction was greater than 1 × 10-6 cm/s but less than 10×10-6 cm/s at three concentrations.It has proven that CZ48 was good in absorption compound.The neutral condition was more conducive to the absorption of CZ48.Temperature had no significant effect on the intestinal absorption of CZ48.The P-gp inhibitor verapamil and MRP inhibitor indomethacin could promote the intestinal absorption of CZ48,and bypass enhancer EDTA can promote the bidirectional transport of CZ48.There is no significant difference in Papp value and efflux rate at three concentrations of MCZ48,which indicates that the intestinal absorption of MCZ48 is not concentration-dependent.At three concentrations,the Papp value of MCZ48 was greater than 1 × 10-6 cm/s and less than 10 ×10-6 cm/s,which has proven that MCZ48 is good in absorption.(3)An in situ rat intestinal perfusion model was established to investigate the absorption of different concentrations of CZ48(250,500,1000 nM)in different intestinal segments,and the effects of P-gp inhibitor verapamil,MRP inhibitor indomethacin,phosphatase inhibitor sodium vanadate and bypass transport enhancer EDTA on CZ48 intestinal absorption.The absorption of different concentrations of MCZ48(250,500,1000 nM)in different intestinal segments was investigated.The results showed that there was no significant difference and no concentration dependency in the absorption of CZ48 in intestinal segments.Verapamil,indomethacin and EDTA could promote the intestinal absorption,and sodium vanadate had no significant effect on the intestinal absorption of CZ48.There was no significant difference and no concentration dependency in the absorption of MCZ48 in intestinal disruption.(4)The intestinal absorption of CZ48 was no difference between MCZ48 and original CZ48.