Radiopharmaceuticals and Mechanism of action

4.2.1 Erbium-169

Radiopharmaceutical: [¹⁶⁹Er]Erbium-citrate (Erbium (¹⁶⁹Er) citrate),

Nuclide: Erbium-169 emits a β particle with a maximum energy of 0.34 MeV, a mean energy of 0.099 MeV, and an average soft tissue range of 0.3 mm. The physical half-life is 9.4 days.
Activity: 20-40 MBq (0.5-1 mL) for metacarpo-phalangeal, 10-20 MBq (0.3-0.5 mL) for proximal interphalangeal, 10-15 MBq for distal interphalangeal and 30-40 MBq (0.8-1 mL) for metatarso-phalangeal joints.
Mechanism of uptake / drug biology

[¹⁶⁹Er]Erbium-citrate contains Erbium-169 as particles (colloid) are phagocytosed by macrophage-like synoviocytes. Radiotherapy of the synovium results in synoviocyte and inflammatory cell necrosis, thereby inhibiting cell proliferation and inflammation. Over time, the synovium becomes increasingly fibrous. The vicious circle of synovitis and joint damage is inhibited or temporarily halted.

4.2.2 Rhenium-186

Radiopharmaceutical: [¹⁸⁶Re]Rhenium-sulphide (Rhenium [186Re]sulphide).
Nuclide: Rhenium-186 emits a β particle with a maximum energy of 1.07 MeV, a mean energy of 0.349 MeV, an average soft tissue range of 1.1 mm and a 9% abundant gamma emission with a photopeak of 0.137 MeV. The physical half-life is 3.7 days.
Activity: 70-190 (3 mL) MBq for shoulder, 70-100 (1-2 mL) MBq for elbow, 40-80 (1-1.5 mL) MBq for wrist, 10-190 (3 mL) MBq for hip, and 70 MBq (1-1.5 mL) for ankle and 37-74 MBq (1-1.5 mL) for the subtalar [49].

Mechanism of uptake / drug biology

[¹⁸⁶Re]Rhenium-sulphide particles (colloids) are phagocytosed by macrophage-like synoviocytes. Radiotherapy of the synovium results in synoviocyte and inflammatory cell necrosis, thereby inhibiting cell proliferation and inflammation. Over time, the synovium becomes increasingly fibrous. The vicious circle of synovitis and joint damage is inhibited or temporarily halted.

4.2.3 Yttrium-90

Radiopharmaceutical: [⁹⁰Y]Yttrium-citrate. Yttri(90-Y) citras, Yttrium (90Y) citrate)
Nuclide: Yttrium-90 emits a β^– particle with a maximum energy of 2.27 MeV, a mean energy of 0.935 MeV and an average soft tissue range of 3.6 mm. The physical half-life is 2.7 days.
Activity for intra-articular injection of [⁹⁰Y]Yttrium- silicate/citrate is 180-200 MBq for the knee

Mechanism of uptake / drug biology

⁹⁰Y citrate particles (colloid) are phagocytosed by macrophage-like synoviocytes. Radiotherapy of the synovium results in synoviocyte and inflammatory cell necrosis, thereby inhibiting cell proliferation and inflammation. Over time, the synovium becomes increasingly fibrous. The vicious circle of synovitis and joint damage is inhibited or temporarily halted.