Keywords: 
• sulfasalazine(SASP) /
• sulfapyridine(SP) /
• 5-aminosalicylic acid(5-ASA) /
• pharmacokinetics and relative bioavailability

Abstract: Objective To evaluate the pharmacokinetics and relative bioavailability of sulfasalazine enteric-coated tablets from two different factories in healthy volunteers. Methods 24 healthy male volunteers were enrolled in the study.A single oral dose(500 mg) of test and reference Sulfasalazine Enteric-coated tablet preparations were given respectively to the volunteers according to randomized two way cross over study design.The washout period was l week.The plasma concentrations of Sulfasalazine(SASP)and sulfapyridine(SP)were determined by HPLC-UV method, the plasma concentrations of 5-aminosalicylic acid(5-ASA) were determined by HPLC-FLU method. Results The pharmacokinetic parameters of SASP, SP and 5-ASA in plasma were as follows:according to AUC_0→t, the relative bioavailability of SASP、SP and 5-ASA was (108.8±24.1)%, (105.0±25.0)% and (94.1±22.0)% in the test preparations; while according to AUC_0→∞, the relative bioavailability of SASP、SP and 5-ASA was (106.9±23.4)%, (104.1±25.0)% and (93.6±22.2)% in the test preparations. Mean plasma concentration-time curve of the test product was highly close to that of the reference product.There was no significant difference in pharmacokinetic parameters between the test and reference preparations of sulfasalazine enteric-coated tablets (P>0.05). Conclusion The results of statistical analysis showed that the two sulfasalazine enteric-coated tablets from different factories in healthy volunteers were bioequivalent.