Previous studies have shown that p-hydroxybenzoic acid (p-HBA) and sodium p-hydroxybenzoate (s-HBA) are both potential drugs for the treatment of ulcerative colitis.In this study,the pharmacokinetic and tissue distribution characteristics of p-HBA and s-HBA were studied in normal mice and cynomolgus monkeys after a single administration of s-HBA.Mice were given 20 mg/kg p-HBA and 20,50 and 100 mg/kg s-HBA by intragastric administration,and cynomolgus monkeys were given 4,10,and 20 mg/kg s-HBA by intragastric administration.The concentrations of p-HBA and s-HBA in plasma and tissue of mice and s-HBA in plasma of cynomolgus monkeys were determined by LC-MS/MS.All plasma and tissue samples were treated with acetonitrile precipitated protein method.At the dose of 20 mg/kg,T_max of p-HBA and s-HBA was 0.08 and 0.08 h,C_max of plasma was 20 453.98 and 30 683.33 ng/kg,and AUC_0-t was 7 180.27 and 12 008.42 ng·h/mL,t_1/2 was 0.57 and 0.59 h,respectively.The C_max and AUC_0-t showed a good linear relationship with dose of s-HBA in mice and cynomolgus monkeys.The high concentration of p-HBA can be detected in the tissues of heart,liver,spleen,lung,kidney,brain and colon of mice after administration of p-HBA and s-HBA.The results showed that p-HBA and s-HBA were quickly absorbed and eliminated in mice and cynomolgus monkeys after oral administration,and were widely distributed in mice tissues,with the highest concentration in kidney and liver.It was speculated that p-HBA had certain targeting property on kidney and liver,and there was no obvious accumulation in all tissues,prompting its good security.