Search

While radiation synovectomy (RSV) constitutes a successful paradigm for the treatment of arthritis, a major cornerstone of its success resides in the selection of appropriate radiolabeled agent. Among the radionuclide used for RSV, the scope of using (177)Lu [T1/2  = 6.65 d, Eβ(max)  = 497 keV, Eγ  = 113 KeV (6.4%), 208 KeV (11%)] seemed to be attractive owing to its suitable decay characteristics, easy availability, and cost-effective production route. The present article describes a formulation of (177)Lu-labeled hydroxyapatite (HA) using ready-to-use kits of HA particles of 1-10 µm size range. The developed kits enable convenient one-step preparation of (177)Lu-HA (400 ± 30 MBq doses) in high radiochemical purity (>99%) and stability at hospital radiopharmacy. The preparation showed promising results in pre-clinical studies carried out in Wistar rats bearing arthritis in knee joints. In preliminary clinical investigation, significant improvement in the disease conditions was reported in 10 patients with rheumatoid arthritis of knee joints treated with 333 ± 46 MBq doses of (177)Lu-HA. The studies reveal that while (177)Lu labeled HA particles holds considerable promise as a cost-effective agent for RSV, the adopted strategy of using HA kits could be a potential step toward wider clinical utilization of radiolanthanide-labeled HA particles., (Copyright © 2014 John Wiley & Sons, Ltd.)

Many radionuclides, namely, 166Ho, 90Y, 165Dy, 32P, 198Au, 186Re, etc. have been used for radio-synovectomy. Silver-111 (T 1/2 7.45 d) can be produced in a nuclear reactor and is a potential therapeutic radionuclide decaying by beta(-) emission (92% E beta max=1.037MeV and 8% by beta(-) decay associated with emission of gamma-rays (E gamma=245.4keV, I gamma=1.33%; E gamma=342.1keV, I gamma=6.7%)). Because of the production feasibility and favourable nuclear properties, 111Ag may find use as a suitable radionuclide for radio-synovectomy. Hydroxyapatite (HA), Ca10(PO4)6(OH)2 is one of the preferred particulates for this application. In this work, [111Ag]Ag-HA particulates were successfully prepared with high-labelling yield ( approximately 97%) at various pH values. The radiochemical purity of the [111Ag]Ag-HA particles was 99.9%. Stability studies for 7 days showed that the [111Ag]Ag-HA particles retained their stability. gamma camera images at 15 min, 24h and 5 d after injection of the particles into rabbits revealed the retention of the activity in the synovial joints of the knee, thereby indicating excellent in vivo stability of [111Ag]Ag-HA particles. Therefore, [111Ag]Ag-HA particles would be a potential therapeutic agent in the management of arthritis.