Standardization and clinical use of a single-vial formulation of technetium-99m-Trodat using autoclave method

Background: Parkinson's disease (PD) is characterized by the degeneration of dopaminergic neurons in the substantia nigra. SPECT imaging using technetium-99m [Tc-99m] labeled trodat is the choice of imaging to differentiate PD from its other forms like drug-induced PD. Aims and Objectives: The main objective of our study was to prepare in-house sterile formulation of [Tc-99m]Tc-trodat and use in clinics. Materials and Methods: The labeling of trodat was standardized using glucoheptonate sodium salt (GHA), stannous chloride dihydrate (in 0.05 N HCl), and ethylenediaminetetraacetic acid (Na-EDTA). The preparation was mixed and autoclaved at 15 psi for 15 min. The standardised formulation was stored at 4 degrees C, -20 degrees C and -80 degrees C and labeling with Tc-99m was tested for up to 6 days. The radiochemical purity, chemical impurities, and endotoxin levels were tested. The frozen formulation was tested in swiss mice (n = 3) for biodistribution studies at 4 h. Around 18 +/- 2 mCi was injected intravenously in each patient (n = 5) and the image was acquired at 4 h post-injection. Results: The radiochemical purity of the preparation was 98.3 +/- 1.4% with a retention time of 16.8 +/- 1.5 min as compared to 4.0 +/- 0.5 min for free Tc-99m. Animal distribution showed highest uptake in liver and dual excretion via hepatobiliary and renal system. [Tc-99m]Tc-trodat imaging was able to differentiate both caudate and putamen. Conclusions: In-house frozen preparation was advantageous, as it has decreased the chance of manual error as compared to daily make up formulations and economical as compared to commercially available kits.