Objective To investigate the characteristics of pharmacoki-netics of pingyangmycin ion -exchanged microspheres in rabbits.Methods A total of 12 Japanese rabbits, half male and half female, were randomly divided into group A and group B.The rabbits in group A and group B were injected with PYM and PYM-MS via external carotid artery separately.The blood samples were obtained at 2, 5, 10, 20, 40, 60 ,90 and 120 minutes after injection and detected by HPLC method.The parameters of pharmacokinetics were analyzed.Results Compared with group A, it showed a slow decrease in terms of concentration-time curves of pingyangmycin in rabbits after administration of PYM-MS in group B;the Cmax [(11.62 ±2.66) vs (58.96 ±4.51) mg· L-1 ] and AUC [(21.06 ±31.33) vs (791.98 ±55.30) mg· L-1 · min] in group B were significantly lower ( P <0.01 ) , but the data of MRT0-60 min was longer in group B [ ( 22.29 ±1.52 ) vs ( 14.20 ±1.24 ) min ] , P <0.01.Conclusion PYM-MS showed definite property of delayed drug release, with a lower plasma concentration.