Technetium-99m based small molecule radiopharmaceuticals and radiotracers targeting inflammation and infection

^99mTc-labeled antibiotics, antifungal drugs, antimicrobial peptides and COX-2 inhibitors are comprehensively reviewed.

Synthesis of (99m)TcN-clinafloxacin Dithiocarbamate Complex and Comparative Radiobiological Evaluation in Staphylococcus aureus Infected Mice

Clinafloxacin dithiocarbamate (CNND) preparation and radiolabeling through [^99mTc ≡ N]²⁺ core with the gamma (γ) emitter (^99mTc) was assessed. The potentiality of the ^99mTc^V ≡ N-CNND complex was investigated as perspective a Staphylococcus aureus (S.a.) in vivo infection radiotracer in terms of radiochemical stability in normal saline (n.s.), human serum (h.s.), binding efficacy with live and heat killed S.a. and biodistribution in female nude mice model (FNMD). More than 90% stability was observed in n.s. for 4 h with the highest yield of 98.70 ± 0.26% at 30 min after reconstitution. In h.s., the ^99mTc^V ≡ N-CNND complex was found stable up to 16 h with 15.35% side products. Maximum in vitro binding (68.75 ± 0.80%, 90 min) with S.a. was observed after 90 min of incubation. In FNMD, (infected with live strain) approximately six-fold higher uptakes was noted in the infected to inflamed and normal muscles. The higher stability in n.s., h.s., higher S.a. (live) up take with specific and targeted in vivo distribution confirmed potentiality of the ^99mTc^V ≡ N-CNND complex as perspective S.a.in vivo infection radiotracer.

Radiosynthesis of (99m)Tc(CO)3-Clinafloxacin Dithiocarbamate and Its Biological Evaluation as a Potential Staphylococcus aureus Infection Radiotracer

BACKGROUND

Clinafloxacin dithiocarbamate (CNND) was radiolabeled with technetium-99m ((99m)Tc) using [(99m)Tc(CO)3(H2O)3](+) and assessed for its radiochemical stability in saline and serum, its in vitro binding with methicillin-resistant Staphylococcus aureus (MRSA) and biodistribution in female nude mice (FNM) artificially infected with live and heat-killed MRSA.

METHODS

In normal saline (NS) the (99m)Tc(CO)3-clinafloxacin dithiocarbamate ((99m)Tc(CO)3-CNND) showed radiochemical stability with a maximum value of 99.10 ± 0.20% and remained stable up to 4 h (92.65 ± 0.18%).

RESULTS

In human serum at 37°C within 16 h of incubation, 14.85% side products as a result of de-tagging developed. Incubation with MRSA gave saturated binding with a maximum value of 72.75 ± 1.20%. Almost six-fold higher uptake was seen in the infected muscle of the FNM as compared to the inflamed and normal muscle. The (99m)Tc(CO)3-CNND complex showed a normal route of excretion from the body of the FNM model.

CONCLUSION

The higher stability in NS, HS, saturated in vitro binding with a live strain of MRSA and six-fold higher uptake in the target organ showed the (99m)Tc(CO)3-CNND complex to be a potential MRSA infection radiotracer.