This study aimed to radiolabel finasteride, a novel 5α-reductase inhibitor, to evaluate its cancer targeting potential in experimental model of prostate carcinogenesis. Finasteride was effectively radiolabeled with Tc and showed>90% labeling efficiency. The radiopharmaceutical was found to be stable up to 6 hours in rat serum at 37°C. The blood kinetics of the Tc-finasteride followed a biphasic release pattern, whereby fast-release phase was observed at 15 seconds and a slow-release phase was observed after 30 minutes of administration. The plasma protein binding of the radio complex observed was 83.89%. For biodistribution studies, the rats were divided into two groups. Group I served as normal controls, while group II was subjected to carcinogen N-methyl-N-nitrosourea (MNU) and hormone testosterone propionate (T) for induction of prostate carcinogenesis, which was confirmed histopathologically. The biodistribution studies on control and carcinogen-treated rats revealed a significant percent-specific uptake in prostate, which was found to be increased significantly as a function of time. The most significant finding of the study was an increase in the percent-specific uptake in prostate of carcinogen-treated animals when compared to the percent-specific uptake in prostate of normal rats after 2 and 4 hours postinjection. The study concludes thatTc-finasteride possesses selectively toward prostate cancer tissue and can be explored further for its role in detection of prostate cancer.

Objective: Considering the 5α-reductase (5AR) inhibitory activity of the oximes and the importance of the ester group in increasing the anti-androgenic property, we reasoned to synthesize a compound having a lactam group in ring D and an ester group at the 3 β position of the androsterone nucleus. The study aims to radiolabel 17-oxo-17a-aza-D-homo-5-androsten-3β-yl phenoxyacetate (17a-aza steroid) with Tc-99m to evaluate its targeted uptake in experimentally induced prostate carcinogenesis in rats. Materials and Methods: The prediction of the optimal interaction and binding affinity of Tc-99m-17-oxo-17a-aza-D-homo-5-androsten-3 β-ylphenoxyacetate (Tc-99m-17a-aza steroid) toward 5AR inhibitor was done using Biopredicta Vlife MDS tool. Tc-99m-17a-aza steroid was developed by direct radiolabeling protocol. The radio-pharmacological characteristics (serum stability, plasma protein-binding ability, and lipophilicity) of the complex were evaluated. Further, the bio-distribution studies of the complex were performed in rats with experimentally induced prostate carcinogenesis. Results: The in-silico analysis exhibits favorable binding of Tc-99m-17a-aza toward 5AR with D score-130.97. The radiochemical purity of Tc-99m-17a-aza was 96.79%. The radio-complex maintained stability in the rat serum for a period of 6 h (hours). Plasma protein binding and Log P o/w value were observed to be 86.23 ± 7.08% and 0.118 ± 0.045, respectively. A significantly enhanced percent-specific uptake was observed in the prostate of rats with induced prostate carcinogenesis. Conclusion: The study concludes that Tc-99m-17a-aza exhibits prostate specificity and can be explored further for its potential as a radionuclide imaging probe.