Idoxifene: report of a phase I study in patients with metastatic breast cancer.
Idoxifene, a novel antiestrogen with reduced estrogenic activity when compared to tamoxifen, has been given to 20 women with metastatic breast cancer, 19 of whom had received tamoxifen previously, in doses between 10-60 mg. Idoxifene had an initial half-life of 15 h and a terminal half-life of 23.3 days. At a maintenance dose of 20 mg, a mean steady-state level of 173.5 ng/ml was achieved. Significant falls in luteinizing hormone and follicle-stimulating hormone were seen, but the falls were not dose related. Idoxifene was well tolerated, with 11 patients complaining of mild symptoms similar to those seen with tamoxifen. Fourteen patients continued idoxifene therapy for 1-56 weeks; 4 patients showed stabilization of disease for 6-56 weeks and 2 patients showed a partial response.
Coombes
R C
RC
Department of Medical Oncology, Charing Cross & Westminster Medical School, London, United Kingdom.
Haynes
B P
BP
Dowsett
M
M
Quigley
M
M
English
J
J
Judson
I R
IR
Griggs
L J
LJ
Potter
G A
GA
McCague
R
R
Jarman
M
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D004702:Endocrine Glands / Q000187:drug effects; D004965:Estrogen Antagonists / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis; D017698:Postmenopause; D013629:Tamoxifen / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000627:therapeutic use
D004965:Estrogen Antagonists; D013629:Tamoxifen; C071362:idoxifene