Preparation and biological evaluation of 99mTc-ropinirole as a novel radiopharmaceutical for brain imaging

Noninvasive brain imaging is a process that allows scientists and physicians to view and monitor the areas of the brain. The aim of this study was to formulate a novel radiopharmaceutical for the detection of brain disorders at early stages in susceptible patients. 99mTc-ropinirole was prepared by the direct complexation of ropinirole with technetium-99m. The results showed that the radiochemical yield 99mTc-ropinirole was 92 +/- 2.87% and the radiochemical yield was evaluated by paper chromatography and HPLC. In vitro studies showed that the formed complex was stable for up to 6 h. In vivo uptake of 99mTc-ropinirole in the brain was 4.87 +/- 0.15% injected dose/g organ at 30 min post-injection, which cleared from the brain with time till it reaches 2.3% at 2 h post-injection indicating that the brain uptake of 99mTc-ropinirole is higher than that of the commercially available 99mTc-HMPAO, which is 2.25% at 30 min. Pre-dosing mice with cold ropinirole reduced the brain uptake to 0.26 +/- 0.01% injected dose/g organ, so this confirms the high specificity and selectivity of this radiotracer for the assessment of the dopamine receptors.