Title:Formulation and In-vivo Characterization of 177Lu-tin-colloid as a
Radiosynovectomy Agent
Volume: 17
Issue: 1
Author(s): Guldem Mercanoglu*, Goksel Alcın, Yusuf Ozturkmen and Tevfik Cermik
Affiliation:
- Department of Pharmacology, Hamidiye Pharmacy Faculty, University of Health Sciences, Istanbul, Turkey
Keywords:
Radiosynovectomy, 177Lu-tin colloid, synovectomy, 177Lu-lutetium, arthritis, antirheumatic drugs.
Abstract:
Introduction: Arthritis is an inflammatory disorder that affects one or more joints of
the body for various reasons, including autoimmune disorders, trauma, or infection. In many
cases, traditional long-term treatment with various drug combinations (NSAIDs, diseasemodifying
antirheumatic drugs, systemic corticosteroids, etc.) can provide relief, but many
joints require additional local treatment. Radiosynovectomy (RSV) is an alternative method to
current treatment options. Both the global supply shortage of 90Y in recent years and the increasing
use of 177Lu-labeled radiopharmaceuticals in the field of nuclear medicine have made it
possible to develop 177Lu-labeled microparticles and test them in small groups as RSV agents.
This study aimed to develop the 177Lu labeled tin colloid formulation and demonstrate its invivo
characterization.
Materials and Methods: Particle size, shape, and labelling efficiency of the four formulations
developed were determined. The formula with the highest labelling efficiency was selected for
further studies. The quality of the formulation was evaluated based on radionuclidic, radiochemical,
and microbial purity. In-vitro stability was evaluated by determining the labelling efficiency.
In-vitro stability was tested in PBS and synovial fluid. The biological characterization was
assessed using SPECT/CT after injecting the formulation into the normal knee joints of the rabbits.
Results: Aggregated colloidal particles were spherical with a particle size of <5 μm. Labelling
efficiency and radiochemical purity were >95 and 97.65% (Rf=0.2), respectively. The
formulation was stable
in vitro for up to 72 hours, both in PBS and synovial fluid. The formulation
was homogeneously distributed in the joint at 0 and 1 hour after injection, and radioactivity-
related involvement and inguinal lymph node involvement due to possible leakage were
not detected in the late period. No pyrogenic/allergic side effects were observed during this period.
Conclusion:
177Lu-tin-colloid was successfully prepared under optimized reaction conditions
with high binding efficiency and radiochemical purity. The radiolabeled colloid was found
to be stable
in-vitro both in PBS and synovial fluid at room temperature. Serial PCET/CT
images revealed that the activity was completely retained within the synovial cavity, with
no activity leakage out of the joint until 48 hours after the injection. With the support of
the results from further clinical studies, it may be possible for the formulation to enter clinical
use.
