Stability evaluation of fractionated MIBI (TCK-50) and MDP (TCK-30) cold kits

Evaluation of in-vitro stability of fractionated MIBI cold kit used for myocardial perfusion imaging and methylene diphosphonate (MDP) cold kit used for bone scintigraphy. Cold kits have been used to prepare radiopharmaceuticals to carry out various nuclear medicine diagnostic studies. A single kit that is used for formulation of multiple patient doses often remains unutilized to the full extent. Moreover, more than two vials are required to be formulated in case of less available activity. Fractionation of kits is therefore necessary for logical usage of these kits. MDP cold kit (TCK-30) and MIBI cold kit (TCK-50) from BRIT, ^99mTcO₄ Na from column generator (BRIT), Universal pH paper, gamma-TLC miniGITA scanner, chemicals (AR/HPLC grade). MDP kit reconstituted with 2.0 ml N₂ purged saline and dispensed into 4 vials (0.5 ml/vial), and MIBI were reconstituted with 1.5 ml sterile saline and fractionated into 3 vials (0.5 ml/vial). Five sets of different conditions were used for reconstitution of MIBI kit: 1 st - 1.5 ml normal saline, 2 nd - 1.5 ml N₂ purged saline, 3 rd - 1.5 ml N₂ purged saline + 120 µg ascorbic acid, 4th - 1.5 ml N₂ purged saline + 300 µg gentisic acid, and 5 th - 1.5 ml N₂ purged saline with 100 µg (and 150 µg) SnCl₂·₂H₂ O per vial. All fractionated vials were stored at −20°C. Vials are labeled with 2 ml of ~30/60 mCi of ^99mTcO₄− after thawing on 0, 1, 3, 5, 8, and 15 th day. Labeled products were checked for pH, color, and percentage of radiochemical purity (RCP) at 0 and 4 h of labeling. Appearance of fractionated labeled kit at various time intervals was found to be clear and its pH was between 5.5 and 6.5 at different conditions. The percentage RCP was >95% for MDP up to 8 days of storage in N₂ purged saline. The percentage RCP of fractionated MIBI kit was found >95% in normal condition on the day of formulation, up to 2 days of storage in N₂ purged saline and ascorbic acid, up to 5 days for gentisic acid, and up to 15 days of storage in added SnCl₂·₂H₂ O. (author)