Effect of raloxifene on activated protein C (APC) resistance in postmenopausal women and on APC resistance and homocysteine levels in elderly men

The effect of selective estrogen receptor modulator administration on the hypothalamic-pituitary-testicular axis in men with idiopathic oligozoospermia

This study evaluates, compares, and contrasts the effects of three selective estrogen receptor modulators (SERMs), namely, tamoxifen, toremifene, and raloxifene, on the hypothalamic-pituitary-testicular axis in 284 consecutive subfertile men with idiopathic oligozoospermia using three therapeutic protocols: [1] tamoxifen, 20 mg, once daily (n = 94); [2] toremifene, 60 mg, once daily (n = 99); and [3] raloxifene, 60 mg, once daily (n = 91). The antiestrogenic effects of SERMs at the hypothalamic level result in a statistically significant increase of gonadotropin levels, which is more marked for tamoxifen and toremifene compared with raloxifene.

Complex actions of sex steroids in adipose tissue, the cardiovascular system, and brain: Insights from basic science and clinical studies

Recent publications describing the results of the Women's Health Initiative (WHI) and other studies reporting the impact of hormone therapy on aging women have spurred reexamination of the broad use of estrogens and progestins during the postmenopausal years. Here, we review the complex pharmacology of these hormones, the diverse and sometimes opposite effects that result from the use of different estrogenic and progestinic compounds, given via different delivery routes in different concentrations and treatment sequence, and to women of different ages and health status. We examine our new and growing appreciation of the role of estrogens in the immune system and the inflammatory response, and we pose the concept that estrogen's interface with this system may be at the core of some of the effects on multiple physiological systems, such as the adipose/metabolic system, the cardiovascular system, and the central nervous system. We compare and contrast clinical and basic science studies as we focus on the actions of estrogens in these systems because the untoward effects of hormone therapy reported in the WHI were not expected. The broad interpretation and publicity of the results of the WHI have resulted in a general condemnation of all hormone replacement in postmenopausal women. In fact, careful review of the extensive literature suggests that data resulting from the WHI and other recent studies should be interpreted within the narrow context of the study design. We argue that these results should encourage us to perform new studies that take advantage of a dialogue between basic scientists and clinician scientists to ensure appropriate design, incorporation of current knowledge, and proper interpretation of results. Only then will we have a better understanding of what hormonal compounds should be used in which populations of women and at what stages of menopausal/postmenopausal life.

The differential association of conjugated equine estrogen and esterified estrogen with activated protein C resistance in postmenopausal women

OBJECTIVES

Clinical trials have demonstrated that oral conjugated equine estrogen (CEE) therapy with or without medroxyprogesterone (MPA) increases venous thrombotic risk but this safety issue has not been investigated for other oral estrogens. Based on observational study findings that esterified estrogen (EE) was not associated with venous thrombotic risk whereas CEE was, we hypothesized that CEE users would be more resistant to activated protein C (APC), a prothrombotic phenotype, than EE users.

METHODS

We conducted an observational, cross-sectional study of postmenopausal women 30-89 years old who were controls in a case-control study of venous thrombosis. Use of CEE, EE, and MPA at the time of phlebotomy was determined using computerized pharmacy records. APC resistance was measured in plasma by the endogenous thrombin potential normalized APC sensitivity ratio. Adjusted mean APC resistance values were compared across estrogen type and CEE:EE ratios are presented.

RESULTS

There were 119 CEE and 92 EE users at the time of phlebotomy. Compared with EE users, CEE users had APC resistance measures that were 52% higher (1.52; 95% confidence intervals: 1.07-2.17) in adjusted analyses. Restricting to modal dose users (0.625 mg) and stratifying by MPA use did not materially change associations.

CONCLUSIONS

CEE use was associated with higher levels of APC resistance when compared with EE use in postmenopausal women. These findings might provide an explanation for the higher risk of venous thromboembolism previously observed with CEE compared with EE use and, if replicated, may have safety implications for women when choosing an estrogen for symptom relief.

Procoagulant state after raloxifene therapy in postmenopausal women

OBJECTIVE

To investigate the effects of raloxifene on the hemostatic system in postmenopausal women.

DESIGN

A prospective longitudinal study.

SETTING

Outpatient clinic of the Faculty of Medicine of Ribeirão Preto, Brazil.

PATIENT(S)

Sixteen postmenopausal women aged 56.8 +/- 5.9 years (mean +/- SD).

INTERVENTION(S)

Raloxifene hydrochloride (60 mg once daily) was administered orally for a period of 6 months.

MAIN OUTCOME MEASURE(S)

Plasma activities of coagulation factors (II, V, VII, VIII, IX, X, XI, XII, and fibrinogen), prothrombin-derived fragment 1+2, and activated protein C (APC) sensitivity ratio were measured at baseline and after 1, 3, and 6 months of treatment.

RESULT(S)

Factor VIII activity increased by 17.1% and 26.9% at 3 and 6 months of treatment, respectively, compared with baseline. Factor XI and FXII activities significantly increased by 10.9% and 43.1%, respectively, after 6 months compared with baseline. A significant reduction of APC sensitivity ratio also was observed after 6 months of treatment.

CONCLUSION(S)

A procoagulant state characterized by increased factor VIII, XI, and XII plasma levels and by reduced APC sensitivity was observed after raloxifene therapy in post-menopausal women.