Preparation of 99mTc radiopharmaceuticals: the effect on radiochemical purity of using sodium chloride injection from plastic ampoules that have been exposed to light.

Objective: To determine whether radiochemical purity is affected when 99mTc radiopharmaceuticals are prepared using sodium chloride injection from plastic ampoules that have been exposed to light.

Methods: Sodium chloride injection from plastic ampoules that were either exposed to light for 7 days or protected from light was used in the preparation of nine common 99mTc radiopharmaceuticals: albumin nanocolloid, exametazime, macrosalb, mebrofenin, medronate, pentetate, sestamibi, succimer and tetrofosmin. Five different batches of ampoules (exposed and unexposed) were used for each radiopharmaceutical. Radiochemical purity was measured by established analytical methods (thin-layer chromatography, liquid chromatography and nuclepore filtration) as specified in the European Pharmacopoeia or by the manufacturer. Analysis was performed within 1 h of preparation and at the products' expiries.

Results: The radiochemical purity of each 99mTc radiopharmaceutical was satisfactory when unexposed sodium chloride injection was used in its preparation. There was a significant difference between exposed and unexposed results (P < 0.05) for 99mTc exametazime (69.0 ± 9.3% vs. 88.6 ± 0.8%), 99mTc albumin nanocolloid (94.3 ± 1.1% vs. 98.8 ± 0.4%) and 99mTc macrosalb (84.0 ± 4.1% vs. 98.0 ± 2.2%) after preparation. Unsatisfactory radiochemical purity was the result of 99mTc pertechnetate impurity. The radiochemical purities of 99mTc albumin nanocolloid and 99mTc macrosalb increased over time and were satisfactory at their expiries.

Conclusion: When 99mTc albumin nanocolloid, 99mTc macrosalb and 99mTc exametazime are prepared using sodium chloride injection from plastic ampoules that have been exposed to light, radiochemical purity is adversely affected. The other 99mTc radiopharmaceuticals tested are unaffected.