Failure of quality control to detect errors in the preparation of technetium-99m disofenin (DISIDA)

Uptake of Tc-99m disofenin is so strongly hepatobiliary that striking appearance of radioactivity in the reticuloendothelial system (RES) is almost certainly caused by improper preparation of the disofenin kit. Four patients who received injections of Tc-99m disofenin demonstrated a pronounced RES biodistribution in addition to the expected hepatobiliary pattern. Since routine quality control testing had not forewarned us of this gross lack of radiochemical purity, Tc-99m disofenin kits were subjected to a variety of insults to elucidate the mechanisms of quality control failure. Assessment of radiochemical purity was conducted using instant thin-layer chromatography (ITLC) and two solvent systems. We concluded that both Tc-99m pertechnetate and Tc-99m sulfur colloid had been injected into the cold disofenin kit. Visual inspections were not reliable for verifying the final radiopharmaceutical product because of dilution of the sulfur colloid by pertechnetate. ITLC testing failed because the assay method being used at that time did not accurately assess the hydrolyzed fraction (colloidal component). Recommendations are made to preclude recurrence of the errors that occurred.