Determination of equilibrium solubility of NCP4 and its partition coefficient

Equilibrium solubility of NCP4 at different pH levels was determined by HPLC and shaking flash method was used to detect its partition coefficients in the n-octanol-water,hydrochloric acid,buffer solution systems.With the condition of 37 °C,the equilibrium solubility of NCP4 in water,hydrochloric acid (pH 1.0) andphosphate buffer solution（pH 2.0,3.0,4.0,5.0,6.0,6.8,7.0,7.4,8.0）were 3.68,24.81,6.25,4.91,6.53,5.98,4.20,4.46,6.39,5.97,17.41 μg/L.In the addition,the lgP（O/W） of NCP4 also in the above condition were 7.31,7.37,not detected (ND),ND,7.40,ND,ND,7.57,6.73,7.43,7.44,respectively.Determination of equilibrium solubility and partition coefficients of NCP4 can provide the basis for its dosage form.The detected values of lgP（O/W） of NC/P4 were more than 5,indicating that NCP4 was not easy to absorb on mucosa.