Evaluation of commercial sulfur colloid kits for the preparation of filtered sulfur colloid

Objectives One of the major uses for Tc99m sulfur colloid (SC) is the preparation of filtered SC for lymphoscintigraphy procedures. There are three commercial SC kits: Anazao Health (old formulation); Anazao Health (new formulation); Pharmalucence, Inc. The total yield of filtered SC (<0.1um) was evaluated for each specific commercial kit.

Methods Three kits were evaluated: Anazao (old); Anazao (new); Pharmalucence. Each SC kit was prepared by adding 0.2ml SC, 0.3ml (high concentration) and 0.4ml (low concentration) Tc99m pertechnetate in a 5ml vial. Following addition of vial A (0.25ml) the reaction vial was heated for 15 minutes, cooled and 0.25ml of vial B added. Radiochemical purity >95% was achieved for all SC preparations. An aliquot of high and low concentration was removed, filtered through a 0.1um filter into a 10ml vial and washed with 1ml of saline. Total yield of filtered SC was determined by measuring activity of residual filter and filtered SC preparation. Yield of filtered SC was expressed as a percentage of total activity added to filter. Radiochemical purity of the final product was assessed.

Results Filtered SC yields from high concentration preparations of Anazao (old), Anazao (new) and Pharmalucence were 17%, 15% and 56%, respectively. Filtered SC yields from low concentration preparations of Anazao (old), Anazao (new) and Pharmalucence were 7%, 7% and 34%, respectively. For both high and low concentration SC preparations, significantly higher yield of filtered SC were achieved using Pharmalucence SC kits. Radiochemical purity of filtered SC was >95%.

Conclusions The yields of filtered SC were evaluated from three commercial SC kits. Highest yields of filtered SC were achieved using Pharmalucence SC with 56% for high concentration and 34% for low concentration formulations