Normal volunteer studies with modified 99Tcm tin colloid.

99Tcm tin colloid, modified by the addition of various amounts of the surfactant Pluronic F68 was evaluated as a new liver imaging agent in normal adult male volunteers. The relative amounts taken up in the liver and spleen were measured by two quantitative methods with a view to establishing the most useful technique. The changes in biodistribution resulting from mechanical shaking during preparation of the colloids and in vitro ageing of the preparations were assessed. The pharmacokinetics of uptake into liver and spleen of the various formulations tested were independent of Pluronic F68 content. However, at low levels of Pluronic F68 the liver:spleen ratio decreased as the colloid preparation was aged before use. At high levels of Pluronic F68 there was increased background activity. An optimum formulation was identified combining low background activity with a stable pattern of biodistribution independent of preparation age.