Synovetin Safety Short Abstract

Introduction: Synovetin OA (Exubrion Therapeutics), a novel preparation of the radionuclide tin-117 m embedded in a homogeneous colloid, has been developed for intra-articular (IA) elbow administration to treat synovial inflammation and mitigate osteoarthritis (OA) in dogs. The short penetration range (0.3 mm) of energy emitted (conversion electrons) by tin-117 m results in apoptosis of synoviocytes and macrophages in inflamed synovium. The device’s safety was evaluated following IA injection of dogs with elbow OA.

Materials and Methods: Following IA injection of Synovetin OA into arthritic elbows of client-owned dogs (n = 69), blood samples for CBC and clinical chemistry, urine samples, and joint fluid samples were obtained at baseline (BL), 1, 3, 6, 9, and 12 months. Nuclear scintigraphy to assess joint retention of the test article was performed 24 hours following treatment.

Results: Some significant variation in urinalysis, CBC, and clinical chemistry values occurred from BL to various posttreatment intervals. However, all values were within normal ranges. Joint-fluid analysis at BL revealed some mononuclear cell inflammation indicative of degenerative joint disease in most dogs, but no posttreatment cytologic abnormalities were observed. Scintigraphy results indicated that tin-117 m was retained within the synovium of all study dogs following intra-articular injection.

Discussion/Conclusion: The consistent, long-term absence of local or systemic side effects in tin-117 m treated dogs was a strong affirmation of the safety of IA injection with Synovetin OA. Joint scintigraphy confirmed that Synovetin OA remains locally sequestered without the possibility of systemic distribution or activity.

Acknowledgment: Drs. Jimmy Lattimer, Lorrie Gaschen, Karanvir Aulakh, Michelle Fabiani, Brian Beale, and Caleb Hudson.