Biological behavior of 67Ga-citrate in New Zealand White rabbits.

The pharmacokinetics, protein binding, excretion and tissue distribution of 67Ga after the administration of 67Ga-citrate to New Zealand White rabbits is described. Data for 67Ga blood levels were best described by an equation with three exponential components exhibiting half lives of 0.25 h, 7.

Effect of cis-platinum treatment on 67Ga-citrate localization and elimination in rabbits.

The treatment of rabbits with a typical dosage schedule of the chemotherapeutic drug cis-platinum resulted in an increased whole body retention of 67Ga-citrate due to decreased urinary and fecal excretion. The biodistribution of the tracer was also affected with most tissues showing greater accumulation. These changes are primarily related to drug-induced renal dysfunction, but other factors may also be involved.

Immediate and delayed effects of cis-platinum treatment on the short term biodistribution of 67Ga-citrate in mice.

The co-administration of a single medium toxic dose (5 mg/kg) of the chemotherapeutic drug cis-platinum (cis-Pt) with 67Ga-citrate was found to have minimal effects on the 3 h tissue distribution of the radiopharmaceutical in mice. When the same drug dose was given at two day intervals preceding the co-administered dose, virtually all tissues accumulated 67Ga to a greater extent. The tissue distribution of radiolabeled cis-Pt supported the development of drug-induced renal dysfunction as the primary cause.

Effect of cis-platinum on the protein binding and pharmacokinetics of 67Ga-citrate.

Cis-platinum, a widely used chemotherapeutic drug, and K2PtCl4, a related complex, were found to inhibit the in vitro protein binding of 67Ga to human transferrin in isolated solution but not to whole serum. Cis-platinum treatment of rabbits resulted in enhanced protein binding and delayed blood clearance of subsequently injected 67Ga-citrate. These effects are related to the toxicity of the drug in vivo.

Reactor production and detection of radiolabeled cis-platinum.

Small quantities of radiolabeled cis-platinum were prepared by two methods. The thermal neutron irradiation of potassium tetrachloroplatinite followed by radiochemical synthesis was compared to the direct irradiation of the cis-platinum itself. Both methods produced usable quantities of tracer, but the direct method proved most practical.