Pharmacokinetics of a single dose of fulvestrant prolonged-release intramuscular injection in postmenopausal women awaiting surgery for primary breast cancer.
Clin Ther
; 25(5): 1440-52, 2003 May.
Article
em En
| MEDLINE
| ID: mdl-12867220
ABSTRACT
OBJECTIVE:
The aim of this study was to describe the pharmacokinetics of 3 different single doses of fulvestrant-a new estrogen receptor (ER) antagonist that downregulates the ER with no known agonist effects-administered as a prolonged-release IM formulation.METHODS:
Pharmacokinetic data were obtained in a randomized, partially blinded, placebo-controlled, parallel-group, Phase I/II multicenter trial involving postmenopausal women with primary breast cancer (clinical stages T1-T3, with tumors that were ER positive or of unknown ER status) awaiting curative-intent surgery. Patients received either IM fulvestrant (50, 125, or 250 mg), oral tamoxifen (20 mg, once daily), or oral placebo (once daily). Treatment started 2 to 3 weeks before surgery and blood was taken at various times up to 12 weeks after fulvestrant administration to assess pharmacokinetic variables.RESULTS:
A total of 200 patients entered the trial, of whom 58 took part in the pharmacokinetic analysis (50 mg, n = 20; 125 mg, n = 16; 250 mg, n = 22). Following single IM injections of fulvestrant, the median time to maximum concentration was 6.98, 6.98, and 6.96 days in the 50-, 125,- and 250-mg dose groups, respectively, with an overall range of 2 to 19 days). The plasma concentration-time profiles were primarily controlled by the rate of absorption from the injection site; post-peak plasma concentrations declined over time and were measurable up to 84 days after administration of fulvestrant 125 and 250 mg. Plasma concentrations at 28 days were 2- to 5-fold lower than the maximum value. Plasma concentration data for the 250-mg dose were best described by a 2-compartment pharmacokinetic model, with an apparent terminal phase half-life of approximately 49 days, beginning approximately 3 weeks after administration. Mean area under the plasma concentration-time curve for days 0 through 28 (AUC 0-28) was proportional for fulvestrant 50, 125, and 250 mg. For a doubling of the dose, an analysis of covariance model of the pharmacokinetic data projected an estimated increase in AUC 0-28 of a factor of 1.84 (95% CI, 1.67 to 2.04).CONCLUSIONS:
The IM formulation of fulvestrant used in this study had predictable, dose-linear pharmacokinetics. The prolonged-release properties of this formulation suggested that it may be well suited for the once-monthly dosing schedule intended for clinical use.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Tamoxifeno
/
Neoplasias da Mama
/
Antineoplásicos Hormonais
/
Estradiol
Tipo de estudo:
Clinical_trials
/
Prognostic_studies
Limite:
Aged
/
Aged80
/
Female
/
Humans
Idioma:
En
Revista:
Clin Ther
Ano de publicação:
2003
Tipo de documento:
Article
País de afiliação:
Reino Unido