Standardization and Clinical Use of a Single-vial Formulation of Technetium-99m-Trodat Using Autoclave Method

Parkinson's disease (PD) is characterized by the degeneration of dopaminergic neurons in the substantia nigra. SPECT imaging using technetium-99m [^99mTc] labeled trodat is the choice of imaging to differentiate PD from its other forms like drug-induced PD.

The main objective of our study was to prepare in-house sterile formulation of [^99mTc]Tc-trodat and use in clinics.

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°C, -20°C and -80°C and labeling with ^99mTc 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.

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 ^99mTc. Animal distribution showed highest uptake in liver and dual excretion via hepatobiliary and renal system. [^99mTc]Tc-trodat imaging was able to differentiate both caudate and putamen.

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.