LB-145 is a macrocyclic ligand, which forms, 200 times more stable complex with Stroncium (Sr) ions, than with calcium ones. The product is not toxic, it has no effect on circulation, respiratory system. 85,90Sr and 144Ce were given oral, i.p., s.c. or by inhalation, LB-145 either prophylactic or 30 (60) minutes after the radiointoxication i.v. or i.p. to the animals. The isotope contents of the organism were measured by whole body autoradiography, liquid scintillation, or by NK 350 ratemeter. One injection given prophylactic inhibited the incorporation of isotopes into the organism, within 24 hours after radiointoxication 75-80% of the isotopes were excreted by urine and faeces on the first day, 90-95% excreted on the first week. Also the isotope contents of femur and scissors were mobilised. The suggested human dose-0.5 g/70 kg bw-can be life-saving antihavaric injection.