Pharmacokinetics and biodistribution of radiolabelled idoxifene: prospects for the use of PET in the evaluation of a novel antioestrogen for cancer therapy.

With a view to evaluating the role of PET imaging in the development of new anticancer drugs, we are investigating the novel antioestrogen pyrrolidino-4-iodotamoxifen (idoxifene). [125I]idoxifene and [131I]idoxifene have been produced in no-carrier-added form using a tributyl stannylated precursor, and the bio-distribution and dynamic behaviour of the compound investigated using syngeneic transplantable mammary tumours in the rat. Our findings support the use of PET imaging with 124I to study the clinical pharmacology of idoxifene. Factors other than hormone receptor levels appear to influence tumour uptake and therefore, possibly the biological effects of this compound.