HUMAN BIODISTRIBUTION OF AN ULTRASOUND CONTRAST AGENT (QUANTISON(TM))BY RADIOLABELING AND GAMMA-SCINTIGRAPHY

The biodistribution and kinetics of an air filled human serum albumin microcapsule formulation (Quantison(TM)) intended for use as an intrav enous ultrasound contrast agent have been examined. 12 healthy subject s were administered with approximately 50 million microcapsules per ki logram body weight, radiolabelled with 50 MBq I-123. Imaging was perfo rmed over a period of 58 h using a large field-of-view gamma camera an d the amount of labelled material present in the blood, urine and faec es measured. Imaging demonstrated that the liver was the organ with th e highest uptake, with a mean uptake of 41.8% (SD 10.4%) of the admini stered dose 1 h following administration. The maximum uptake of the ag ent in the lungs was low, mean 4.0% (SD 3.4%). A small amount of uptak e was visible in the bone marrow; however, this was not quantifiable. There was also evidence of minimal myocardial activity within 5 min of administration. No adverse events were observed and there were no cha nges in any of the individual post-study indices. The present study de monstrates the safety of Quantison(TM). Gamma scintigraphy played a us eful role in confirming the biodistribution of the agent with little l ung uptake, high liver uptake and evidence of myocardial uptake.