Synthesis of 4-Amino-1-Hydroxy-Butane-1,1-Diphosphonate (AHBDP) - Stannous Complexes for the Preparation of Ahbdp-Sn(II)-Tc and its Biodistribution in Rats

Abstract

The new potential tracer of bone imaging, AHBDP-Sn(II)-TcO.3H₂O was synthesized by reducing the TcO₄⁻ to TcO₂⁺ in the presence of AHBDP and Sn(ll)’s reducing agent. We found that tin rapidly forms a stable complex with AHBDP, giving AHBDP-Sn(II).3H₂O. In the excess of AHBDP-Sn(ll).3H₂O, the AHBDP-Sn(II).3H₂O coordinates with TcO₂⁺ to give AHBDP-Sn(II)-TcO.3H₂O which could polymerise or oligomerise to give hydrophobic species. The overall process appears as a first-order reaction (K= 0.67 ± 0.005s⁻¹). In rats, the fixation of AHBDP-Sn(II)-^99mTcO. 3H₂O on bone is homogeneous and the scintigraphic images have the same quality as those of 1-hydroxymethane-1,1-diphosphonate-Technetium (HMDP-^99mTc). The activity in non-target organs was neglible.

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