[Studies on gelatin microspheres-in-oil emulsion of pingyangmycin]

As a drug for lymphosarcoma, pingyangmycin (A5) is not widely used because of its toxicities, short half-life and low affinity to lymph. For the purpose of delivering A5 to the lymph system to strengthen and sustain its effects and to lower its toxicities, its gelatin microspheres-in-oil emulsion (S/O) was studied in vitro and in vivo. By ultrasonication, gelatin microspheres with diameters of 1.67 +/- 0.69 microns were homogeneously dispersed in oil to form the S/O, which was a pseudoplastic flow and stable under 0 degrees C for at least 1 month. With the content of 14.03 +/- 0.15 mg.ml-1, A5 released from the emulsion in a zero order rate with t0.5 of 12.0 h. In vivo experiments showed that the S/O emulsion exhibited potent lymphotropicity, prolonged plasma concentration and a probably lower pulmonary toxicity.