Pharmacokinetics of isoflavones, daidzein and genistein, after ingestion of soy beverage compared with soy extract capsules in postmenopausal Thai women

BACKGROUND: Isoflavones from soybeans may provide some beneficial impacts on postmenopausal health. The purpose of this study was to compare the pharmacokinetics and bioavailability of plasma isoflavones (daidzein and genistein) after a single dose of orally administered soy beverage and soy extract capsules in postmenopausal Thai women. METHODS: We conducted a randomized two-phase crossover pharmacokinetic study in 12 postmenopausal Thai women. In the first phase, each subject randomly received either 2 soy extract capsules (containing daidzin : genistin = 7.79 : 22.57 mg), or soy beverage prepared from 15 g of soy flour (containing daidzin : genistin = 9.27 : 10.51 mg). In the second phase, the subjects received an alternative preparation in the same manner after a washout period of at least 1 week. Blood samples were collected immediately before and at 0.5, 1, 2, 4, 6, 8, 10, 12, 24 and 32 h after administration of the soy preparation in each phase. Plasma daidzein and genistein concentrations were determined by using high performance liquid chromatography (HPLC). The pharmacokinetic parameters of daidzein and genistein, i.e. maximal plasma concentration (C(max)), time to maximal plasma concentration (T(max)), area under the plasma concentration-time curve (AUC) and half-life (t(1/2)), were estimated using the TopFit version 2.0 software with noncompartmental model analysis. RESULTS: There were no significant differences in the mean values of C(max)/dose, AUC(0–32)/dose, AUC(0-∝)/dose, T(max), and t(1/2 )of genistein between both preparations. For pharmacokinetic parameters of daidzein, the mean values of C(max)/dose, T(max), and t(1/2 )did not significantly differ between both preparations. Nonetheless, the mean AUC(0–32)/dose and AUC(0-∝)/dose after administration of soy extract capsules were slightly (but significantly, p < 0.05) higher than those of soy beverage. CONCLUSION: The bioavailability of daidzein, which was adjusted for the administered dose (AUC/dose), following a single oral administration of soy beverage was slightly (but significantly) less than that of soy extract capsules, whereas, the bioavailability adjusted for administered dose of genistein from both soy preparations were comparable. The other pharmacokinetic parameters of daidzein and genistein, including C(max )adjusted for the dose, T(max )and t(1/2), were not different between both soy preparations

Breast cancer risk associated with different HRT formulations: a register-based case-control study

BACKGROUND: Previous epidemiological studies have inconsistently shown a modestly increased breast cancer risk associated with hormone replacement therapy (HRT). Limited information is available about different formulations – particularly concerning different progestins. METHODS: A case-control study was performed within Germany in collaboration with regional cancer registries and tumor centers. Up to 5 controls were matched breast cancer cases. Conditional logistic regression analysis was applied to estimate crude and adjusted odds ratios (OR) and 95% confidence intervals (95% CI). Stratified analyses were performed to compare the risk of different estrogens, progestins, and combinations. RESULTS: A total of 3593 cases of breast cancer were identified and compared with 9098 controls. The adjusted overall risk estimate for breast cancer (BC) associated with current or past use of HRT was 1.2 (1.1–1.3), and almost identical for lag times from 6 months to 6 years prior to diagnosis. No significant trend of increasing BC risk was found with increasing duration of HRT use, or time since first or last use in aggregate. Many established BC risk factors significantly modified the effect of HRT on BC risk, particularly first-degree family history of BC, higher age, lower education, higher body mass index (BMI), and never having used oral contraceptives (OCs) during lifetime. Whereas the overall risk estimates were stable, the numbers in many of the sub-analyses of HRT formulation groups (estrogens, progestins, and combinations) were too small for strong conclusions. Nevertheless, the BC risk seems not to vary much across HRT formulation subgroups. In particular, no substantial difference in BC risk was observed between HRT containing conjugated equine estrogens (CEE) or medroxyprogesterone acetate (MPA) and other formulations more common in Europe. CONCLUSION: The BC risk of HRT use is rather small. Low risk estimates for BC and a high potential for residual confounding and bias in this observational study do not permit causal conclusions. Apparently, there is not much variation of the BC risk across HRT formulations (estrogens, progestins). However, the small numbers and the overlapping nature of some of the subgroups suggest cautious interpretation

Der Stellenwert rekombinanter Gonadotropine in der Behandlung des unerfüllten Kinderwunsches.

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Pulsatile subcutaneous versus bolus intramuscolar gonadotropin administration after pituitary suppression with a long-acting GnRH analogue: a controlled prospective study.

The potential advantages of pulsatile s.c. administration instead of daily bolus i.m.administration of human urinary gonadotrophin preparations were tested after the administration of a long-acting gonadotrophin-releasing hormone (GnRH) analogue within a programme for in-vitro fertilization (IVF) and embryo transfer. First, the pharmacokinetic properties of human urinary gonadotrophins were analysed with immunological and biological methods, both during bolus i.m. injections and during pulsatile s.c. administration. Second, a prospective randomized controlled study was performed in 75 patients undergoing IVF/embryo transfer in whom the effects of pulsatile s.c. administration were compared with the effects of single daily bolus i.m. injections of the same gonadotrophin preparation. The results showed that neither method of gonadotrophin administration induced measurable changes in the serum concentration of luteinizing hormone (LH). Both oestradiol and andro-stenedione concentrations were slightly lower during pulsatile s.c. gonadotrophin administration, suggesting that this method of gonadotrophin administration results in less LH occupying the ovarian LH receptors. Pulsatile s.c. gonadotrophin administration resembles a continuous infusion of follicle-stimulating hormone (FSH). Significant fluctuations in the serum concentrations of FSH were observed during single daily bolus i.m. administration of human urinary gonadotrophins, but the pregnancy rate of IVF/embryo transfer per cycle after pulsatile s.c. administration was not significantly better than after the daily bolus i.m. injection of gonadotrophins (42.1 versus 37.2%). It is concluded that pulsatile s.c. administration of gonadotrophins instead of single daily injections does not improve the pregnancy rate in IVF/embryo transfe