Raloxifene: a review of its use in postmenopausal osteoporosis

In vitro bioactivation of bazedoxifene and 2-(4-hydroxyphenyl)-3-methyl-1H-indol-5-ol in human liver microsomes

Bazedoxifene is a selective estrogen receptor modulator (SERM) that has been developed for use in post-menopausal osteoporosis. However, it contains a potentially toxic 5-hydroxy-3-methylindole moiety. Previous studies on the 5-hydroxyindole and the 3-alkylindole-containing drugs indometacine, zafirlukast and MK-0524 structural analogs have shown that they are bioactivated by cytochrome P450s through a dehydrogenation process to form quinoneimine or 3-methyleneindolenine electrophilic species. In the present study, bazedoxifene was synthesized and then evaluated, together with raloxifene and 2-(4-hydroxyphenyl)-3-methyl-1H-indol-5-ol (13), a 3-methyl-5-hydroxyindole-based structural fragment of bazedoxifene, for its ability to form reactive electrophilic species when incubated with human liver microsomes (HLMs) or recombinant CYP isozymes. We showed that bazedoxifene was bioactivated only in trace amounts with recombinant CYP isozymes. In contrast, the N-dealkylated fragment of bazedoxifene (2-(4-hydroxyphenyl)-3-methyl-1H-indol-5-ol) was bioactivated in considerable amounts to an electrophilic intermediate, which was trapped with glutathione and identified by LC-MS/MS. This suggests that bazedoxifene would require initial N-dealkylation, which could subsequently lead to the formation of the reactive intermediate. However, such an N-dealkylated metabolite of bazedoxifene was not detected after the incubation of bazedoxifene in HLM or recombinant CYP isozymes.

Long-term treatment of osteoporosis in postmenopausal women: a review from the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) and the International Osteoporosis Foundation (IOF)

INTRODUCTION

Postmenopausal osteoporosis is a chronic disease requiring treatment that balances long-term fracture efficacy against risk.

METHODS

We reviewed the efficacy and safety of calcium and vitamin D, the selective estrogen receptor modulators (SERMs), the bisphosphonates, denosumab, and strontium ranelate in studies of 3 years or longer.

RESULTS

Six trials lasted for 5 years, and seven went beyond that. The evidence beyond 5 years is generally weak, mainly due to methodological issues (open-label design, small samples, or absence of placebo control). Although calcium and vitamin D appear to be beneficial, the data are insufficient to evaluate benefits and risk beyond 3 years. The fracture efficacy of SERMs beyond 5 years is not known, though increases in bone mineral density (BMD) appear to be maintained. The SERMs have good long-term safety, including protective effects against breast cancer. The bisphosphonates have established fracture efficacy to 3 years, and 4 or 5 years with alendronate and risedronate. The evidence beyond 5 years indicates sustained increases in BMD. The safety of the bisphosphonates does not appear to be modified with time, with the possible exceptions of atypical subtrochanteric fracture and other events of unknown frequency. Denosumab has been tested up to 5 years, with continued increased in BMD and no reported safety issues. There is evidence for fracture efficacy of strontium ranelate, and sustained increases in BMD over 10 years. Strontium ranelate has good long-term safety.

CONCLUSION

Robust long-term studies are relatively rare for the osteoporosis treatments, and generally show maintenance of BMD and, for some agents, an additional reduction in fracture incidence.

Bazedoxifene: a review of its use in the treatment of postmenopausal osteoporosis

Bazedoxifene (Conbriza®, Viviant®) is the first third-generation selective estrogen receptor modulator (SERM) and it is approved for the treatment of postmenopausal osteoporosis in the EU and Japan. Bazedoxifene contains an indole-based core binding domain that binds with high affinity to estrogen receptors and exhibits favourable effects on bone and lipid profiles, with no clinically relevant endometrial or breast stimulation. Oral bazedoxifene once daily reduced the incidence of new vertebral fractures in patients with postmenopausal osteoporosis in a large, well designed trial of 3 years' duration; both bazedoxifene and raloxifene were significantly more effective than placebo. Neither bazedoxifene nor raloxifene reduced the incidence of nonvertebral fractures in the overall study population; however, bazedoxifene, but not raloxifene, reduced the rate of nonvertebral fractures in high-risk patients. Moreover, data from patients who continued to receive the drug during a 2-year extension phase of this trial indicate that bazedoxifene continues to provide protection against new vertebral fractures for up to 5 years. Bazedoxifene also increases bone mineral density and reduces the levels of bone turnover markers. Bazedoxifene was generally well tolerated and did not detrimentally affect the reproductive tract or breast tissue in clinical trials, thereby demonstrating a favourable risk-benefit profile. A pharmacoeconomic analysis conducted from an EU perspective predicted bazedoxifene to be cost effective in some EU countries. Therefore, bazedoxifene presents another useful option for the treatment of postmenopausal osteoporosis, especially in those at high risk for osteoporotic fracture.

Pharmacology and clinical use of sex steroid hormone receptor modulators

Sex steroid receptors are ligand-triggered transcription factors. Oestrogen, progesterone and androgen receptors form, together with the glucocorticoid and mineralocorticoid receptors, a subgroup of the superfamily of nuclear receptors. They share a common mode of action, namely translating a hormone-i.e. a small-molecule signal-from outside to changes in gene expression and cell fate, and thereby represent "natural" pharmacological targets.For pharmacological therapy, these receptors have originally been addressed by hormones and synthetic hormone analogues in order to overcome pathologies related to deficiencies in the natural ligands. Another major use for female sex hormone receptor modulators is oral contraception, i.e. birth control.On the other side, blocking the activity of sex steroid receptors has become an established way to treat hormone-dependent malignancies, such as breast and prostate cancer.In this review, we will discuss how the experience gained from the classical pharmacology of these receptors and their molecular similarities led to new options for the treatment of gender-specific diseases and highlight recent progress in medicinal chemistry of sex hormone-modulating drugs.

Adverse reactions and drug-drug interactions in the management of women with postmenopausal osteoporosis

The pharmacological management of disease should involve consideration of the balance between the beneficial effects of treatment on outcome and the probability of adverse effects. The aim of this review is to explore the risk of adverse drug reactions and drug-drug interactions with treatments for postmenopausal osteoporosis. We reviewed evidence for adverse reactions from regulatory documents, randomized controlled trials, pharmacovigilance surveys, and case series. Bisphosphonates are associated with gastrointestinal effects, musculoskeletal pain, and acute-phase reactions, as well as, very rarely, atrial fibrillation, atypical fracture, delayed fracture healing, osteonecrosis of the jaw, hypersensitivity reactions, and renal impairment. Cutaneous effects and osteonecrosis of the jaw are of concern for denosumab (both very rare), though there are no pharmacovigilance data for this agent yet. The selective estrogen receptor modulators are associated with hot flushes, leg cramps, and, very rarely, venous thromboembolism and stroke. Strontium ranelate has been linked to hypersensitivity reactions and venous thromboembolism (both very rare) and teriparatide with headache, nausea, dizziness, and limb pain. The solidity of the evidence base depends on the frequency of the reaction, and causality is not always easy to establish for the very rare adverse reactions. Drug-drug interactions are rare. Osteoporosis treatments are generally safe and well tolerated, though they are associated with a few very rare serious adverse reactions. While these are a cause for concern, the risk should be weighed against the benefits of treatment itself, i.e., the prevention of osteoporotic fracture.

Adherence and persistence in patients with postmenopausal osteoporosis treated with raloxifene

OBJECTIVE

A major impediment in osteoporosis care is poor therapeutic adherence. Real-life surveys show that adherence and persistence with oral bisphosphonates decrease to 30-60% within 1 year. The aim of this study was to analyze the adherence and persistence with raloxifene in patients visiting our outpatient clinic.

MATERIAL AND METHODS

A total of 342 patients were evaluated from the conventional osteoporosis practice receiving treatment with raloxifene. Patient self-reporting was combined with the medication possession ratio (MPR) assessed via prescription refill counts. In addition, persistence and other self-reported and patient file-based data were assessed.

RESULTS

The final analysis comprised 300 patients with a mean age of 66.3 years (standard deviation ± 7.2 years). At 6 months 84%, at 12 months 81%, at 24 months 78% and at 36 months 77% of patients were persistent with therapy according to patients' self-reports. If MPR and self-reported data were combined, 56%, 48% and 35% of patients remained on therapy at 12, 24 and 36 months, respectively. The mean duration of therapy was 19 months with a mean MPR of 52.8%. Finally, 31.7% of all patients were classified as adherent. Significant correlation to adherence was found for tolerability and motivational factors.

CONCLUSION

This study revealed that approximately half of the patients treated with raloxifene in regular clinical practice stay on therapy for the first 2 years. Furthermore, the patients do not adhere sufficiently to the recommended dosage, and reduced clinical efficacy in clinical practice is presumable. The reasons for non-adherence comprise tolerability and motivational factors but further investigation is needed.

CYP3A4-Mediated oxygenation versus dehydrogenation of raloxifene

Raloxifene was approved in 2007 by the FDA for the chemoprevention of breast cancer in postmenopausal women at high risk for invasive breast cancer. Approval was based in part on the improved safety profile for raloxifene relative to the standard treatment of tamoxifen. However, recent studies have demonstrated the ability of raloxifene to form reactive intermediates and act as a mechanism-based inhibitor of cytochrome P450 3A4 (CYP3A4) by forming adducts with the apoprotein. However, previous studies could not differentiate between dehydrogenation to a diquinone methide and the more common oxygenation pathway to an arene oxide as the most likely intermediate to inactivate CYP3A4. In the current work, (18)O-incorporation studies were utilized to carefully elucidate CYP3A4-mediated oxygenation versus dehydrogenation of raloxifene. These studies established that 3'-hydroxyraloxifene is produced exclusively via CYP3A4-mediated oxygenation and provide convincing evidence for the mechanism of CYP3A4-mediated dehydrogenation of raloxifene to a reactive diquinone methide, while excluding the alternative arene oxide pathway. Furthermore, it was demonstrated that 7-hydroxyraloxifene, which was previously believed to be a typical O(2)-derived metabolite of CYP3A4, is in fact produced by a highly unusual hydrolysis pathway from a putative ester, formed by the conjugation of raloxifene diquinone methide with a carboxylic acid moiety of CYP3A4, or other proteins in the reconstituted system. These findings not only confirm CYP3A4-mediated dehydrogenation of raloxifene to a reactive diquinone methide but also suggest a novel route of raloxifene toxicity.

Comparative evaluation of raloxifene versus estrogen: Progestin on symptomatology, endometrium, and lipid profile in postmenopausal women

The objective of the study was to evaluate the effects of raloxifene and estrogen progesterone (E + P) combination on symptoms, endometrium, and lipid profile in postmenopausal women. Ninety healthy postmenopausal women were enrolled and allocated to three groups namely E + P, raloxifene, and controls. These groups were given 0.625 mg conjugated estrogen and 2.5 mg medroxyprogesterone, 60 mg raloxifene and no therapy, respectively. Symptomatology and lipid profile were evaluated at 3, 6, and 12 months. Endometrial thickness was evaluated at 6 and 12 months, and endometrial biopsy was repeated at 12 months. The demographic profile of the women in the three different groups was comparable. In addition, the symptomatology, lipid profile, mean endometrial thickness, and endometrial biopsy categorization were comparable. E + P and raloxifene were equally effective in improving the postmenopausal symptoms and lipid profile. E + P had stimulatory effect on the endometrium, whereas raloxifene was found to be neutral.

A rat model of epilepsy in women: a tool to study physiological interactions between endocrine systems and seizures

Epilepsy in women is influenced by endocrine status and antiepileptic drugs, but without an animal model, the effects of endocrine variables and antiepileptic drugs cannot be easily dissociated from the influence of epilepsy itself. Animal models have had limited utility because experimentally induced seizures typically result in reproductive failure. This study was conducted to develop an improved animal model. The muscarinic convulsant pilocarpine was used to elicit status epilepticus (SE) in adult female Sprague Dawley rats. The selective estrogen receptor modulator raloxifene was administered 30 min before pilocarpine. An anticonvulsant barbiturate, pentobarbital, was injected 5-10 min after the onset of SE and at least once thereafter to minimize acute convulsions. Mortality, morbidity, estrous cyclicity, and the ultimate success of the procedure (i.e. induction of recurrent, spontaneous seizures) were monitored. The combination of raloxifene and pentobarbital led to significantly improved estrous cyclicity compared with previous methods. Animals treated with raloxifene and pentobarbital became epileptic, as defined by the recurrence of spontaneous convulsions in the weeks after SE. The results of this study provide an improved animal model to examine the interactions between seizures and ovarian hormone secretion. The results also suggest that treatment of SE with raloxifene may benefit women with SE.

Managing the risk of invasive breast cancer in women at risk for breast cancer and osteoporosis: the role of raloxifene

Raloxifene hydrochloride is a selective estrogen receptor modulator (SERM) that has antiestrogenic effects on breast and endometrial tissue and estrogenic effects on bone, lipid metabolism, and blood clotting. Raloxifene significantly improves serum lipids and serum markers of cardiovascular disease risk, but it has no significant effect on the risk of primary coronary events. A meta-analysis of randomized, double-blind, placebo-controlled trials of raloxifene for osteoporosis showed the odds of fracture risk were 0.60 (95% confidence interval [CI] = 0.49–0.74) for raloxifene 60 mg/day compared with placebo. During 8 years of follow-up in an osteoporosis trial, the raloxifene group had a 76% reduction in the incidence of invasive ER-positive breast cancer compared with the placebo group. In the STAR trial, the incidence of invasive breast cancer was 4.30 per 1000 women-years with raloxifene and 4.41 per 1000 with tamoxifen; RR = 1.02; 95% CI, 0.82–1.28. The effect of raloxifene on invasive breast cancer was, therefore, equivalent to that of tamoxifen with more favorable rates of adverse effects including uterine malignancy and clotting events. Millions of postmenopausal women could derive net benefit from raloxifene through reduced rates of fracture and invasive breast cancer.

The NSABP Study of Tamoxifen and Raloxifene (STAR) trial

In the Study of Tamoxifen and Raloxifene (STAR) trial, postmenopausal women at increased risk of breast cancer received either oral tamoxifen (20 mg/day) or raloxifene (60 mg/day) over 5 years. There were an equal number of cases of invasive breast cancer in women assigned to tamoxifen and raloxifene. There were fewer cases of noninvasive breast cancer in the tamoxifen group than in the raloxifene group (risk ratio [RR]: 1.40; 95% confidence interval [CI]: 0.98-2.02). There were more cases of uterine cancer with tamoxifen than with raloxifene (RR: 0.62; 95% CI: 0.35-1.08). Thromboembolic events occurred less often in the raloxifene group (RR: 0.70; 95% CI: 0.54-0.91) and there were fewer cataracts and cataract surgeries in the women taking raloxifene (RR: 0.79; 95% CI: 0.68-0.92). The STAR trial has shown that raloxifene is as effective as tamoxifen in reducing the risk of invasive breast cancer and has a lower risk of adverse events but a nonstatistically significant higher risk of noninvasive breast cancer. The risk of other cancers, fractures, ischemic heart disease and stroke is similar for both drugs.

Effect of testosterone, raloxifene and estrogen replacement on the microstructure and biomechanics of metaphyseal osteoporotic bones in orchiectomized male rats

Introduction

Currently, osteoporosis research is rarely undertaken in males but an increase in male life expectancy in the company of hypogonadism suggests the necessity for potential therapeutic options.

Materials and methods

In this study, the changes in bone structure under standardized testosterone- (T), raloxifene- (R) and estrogen (E)-supplemented diets were analyzed in osteoporotic castrated male rats.

Results

Unexpected biomechanical results could be only explained by the histomorphometry, but not by BMD measurements obtained from the qCT. All tested substances showed a significant improvement in the trabecular network (trabecular bone area for C: 2.55 mm², T: 4.25 mm², R: 4.22 mm² and E: 4.28 mm²), and suggests that the bone structure was preserved. For the metaphyseal cortical bone, a significant loss was detected in T (CBP: 18.7%) compared to R (CBP: 30.0%), E (CBP: 26.8%) and even to the osteoporotic control (CBP: 28.6%). This explains the observed early mechanical final failure after T supplementation. However, due to the preserved trabecular bone in T, the occurrence of the first microfractures (yL: 49 ± 21.4 N) was significantly later than in the osteoporotic control (yL: 39.5 ± 15.5 N). Raloxifene performed well in hindering the bone loss associated with osteoporosis. However, its effect (yL: 83.3 ± 16.5 N) did not approach the protective effect of E (yL: 99.2 ± 21.1 N).

Conclusion

Testosterone only preserved the deterioration of the trabecular bone but not of the cortical bone. Raloxifene prevented the bone loss associated with osteoporosis at all bony structures. This effect did not approach the protective effect of estrogen on trabecular bone, but it is more suitable for male individuals because it has no feminizing effects on the subject.

Raloxifene: a review of its use in the prevention of invasive breast cancer

Raloxifene (Evista) is a second-generation selective estrogen receptor modulator (SERM) that functions as an estrogen antagonist on breast and uterine tissues, and an estrogen agonist on bone. It is available in many countries worldwide for the treatment and prevention of osteoporosis in postmenopausal women, and has also been approved in the US for reducing the risk of invasive breast cancer in postmenopausal women with osteoporosis or postmenopausal women at increased risk of invasive breast cancer.Raloxifene reduces the risk of invasive breast cancer in postmenopausal women at high risk of invasive breast cancer and in postmenopausal women with osteoporosis. In addition, it is a well established agent for the prevention and treatment of osteoporosis. There was no significant difference between raloxifene and tamoxifen in the reduction in the risk of invasive breast cancer achieved in postmenopausal women at high risk of such cancer. Raloxifene was associated with an increased, albeit rare, risk of venous thromboembolism across several placebo-controlled trials and an increased risk of fatal stroke in one placebo-controlled trial in postmenopausal woman at increased risk for major coronary events. However, raloxifene was associated with a lower risk of venous thromboembolic events and cataracts than tamoxifen in a head-to-head trial. The choice of chemoprevention agent must consider a risk-benefit assessment for each individual patient. In this context, raloxifene is a valuable option for the prevention of invasive breast cancer in postmenopausal women with osteoporosis or at high risk of invasive breast cancer.

Raloxifene has favourable effects on metabolic parameters but has no effect on left ventricular function in postmenopausal women

In this prospective randomized study, we investigated the effect of raloxifene on the echocardiographic parameters of left ventricular diastolic and systolic function and on blood levels of lipids, homocysteine, and lipoprotein (a) in postmenopausal osteoporotic patients and compared the results with those treated with risedronate. A total of 44 women were included in the study. Patients were randomized into two groups. Twenty-two patients received raloxifene 60 mg/day (group 1), and 22 patients received risedronate 5mg/day (group 2; the control group). All patients underwent quantitative two-dimensional pulsed wave Doppler and tissue Doppler echocardiography. Levels of fasting total-C, HDL-C, LDL-C, triglycerides, homocysteine, and lipoprotein (a) were measured. All echocardiographic and biochemical parameters were assessed at the beginning of the study and after the 6-month follow-up. Demographic characteristics and baseline metabolic and echocardiographic parameters were similar in the two groups. After 6 months of the therapy, serum levels of total-C, LDL-C, and homocysteine decreased significantly (P=.04, P=.02, P=.008, respectively) in the treated group when compared with the control group. All echocardiographic measurements except a wave from level of basal interventricular septum were similar in the two groups both before and after 6 month of therapy. In the control group, a wave from level of basal interventricular septum increased significantly (P=.019). In conclusions raloxifene may decrease serum levels of total-C, LDL-C, and homocysteine in postmenopausal osteoporotic patients and raloxifene therapy seems to have no significant effect on left ventricular systolic and diastolic function.

Single and multiple ascending dose studies of a novel tissue-selective oestrogen receptor modulator, CHF 4227, in healthy postmenopausal women

AIMS

We evaluated the tolerability, adverse events profile, pharmacokinetics, and pharmacodynamics of CHF 4227, a new selective oestrogen receptor modulator (SERM), in healthy postmenopausal women.

METHODS

Two phase I studies were conducted according to a double-bind, placebo-controlled design. Subjects were randomized to receive six single (5-400 mg) or five multiple oral doses of CHF 4227 for 28 days (5-100 mg).

RESULTS

No vaginal bleeding and no changes in either endometrial thickness or the placenta protein 14 marker were found after 4 weeks of treatment. The compound did not induce negative effects on the fibrinolytic system. After 28 days of treatment, CHF 4227 decreased both total and LDL cholesterol concentrations (maximum decreases from baseline of 17.4% (95% CI 7.0, 27.7) and 27.6% (95% CI 9.0, 46.3), respectively). Decreases in both serum and urinary type-I C-terminal collagen telopeptide were also observed producing maximum changes of 40.6% (95% CI 29.5, 51.7), and 41.7% (95% CI 20.3, 56.8), respectively. CHF4227 (5 and 10 mg) induced near maximal oestrogen-like effects on bone markers and serum lipids without causing hot flushes. The pharmacokinetics of CHF 4227 were characterized by a slow absorption, a long elimination half-life (31-42 h after single administration) and dose linearity with respect to C(max) and AUC up to 100 mg.

CONCLUSIONS

CHF 4227 is a well-tolerated SERM when administered once daily for 28 days. It is potentially active on bone resorption and serum lipids, without affecting the endometrium and without worsening hot flushes. CHF 4227 is a promising agent for the treatment of several conditions in postmenopausal women.

Effect of ormeloxifene on ovariectomy-induced bone resorption, osteoclast differentiation and apoptosis and TGF beta-3 expression

Effect of ormeloxifene, a multifunctional selective estrogen receptor modulator, on prevention of ovariectomy-induced bone resorption in retired breeder female rats, osteoclastogenesis using bone marrow cells from adult Balb/c mice cultured in presence of M-CSF and RANKL, osteoclast apoptosis using terminal deoxynucleotidyl transferase fragment end labeling and TGF beta-3 expression were investigated. Raloxifene, a benzothiophene reported to mimic effects of estrogen in bone, and estradiol were used for comparison. Ormeloxifene (10(-6) and 10(-8)M) significantly inhibited osteoclastogenesis (P<0.001 versus vehicle control) as evidenced by lower number of TRAP-positive osteoclasts in bone marrow cultures and caused apoptosis of osteoclasts. The effect was almost equivalent to that observed in presence of estradiol-17 beta, except that significant number of cells undergoing apoptosis was evident even at 10(-9)M concentration of estradiol-17 beta (P<0.001). Raloxifene, though inhibited osteoclastogenesis at much lower concentrations (10(-8) to 10(-12)M; P<0.001), failed to cause apoptosis of osteoclasts at any of the concentrations used. While ormeloxifene, raloxifene and ethynylestradiol significantly prevented ovariectomy-induced bone loss in vivo in retired breeder female rats, prevention of ovariectomy-induced decrease in BMD and trabecular network of proximal tibia, calcium and phosphorus levels in femur and tibia and prevention of ovariectomy-induced down-regulation of TGF beta-3 expression in lumbar vertebrae was of lower order in raloxifene- than ormeloxifene- or ethynylestradiol-supplemented females. Both the SERMs, however, produced considerable estrogenic effects at the uterine level as evidenced by increase in weight, total and endometrial area and luminal epithelial cell height; the effect being generally greater in raloxifene- than ormeloxifene-treated rats. Findings demonstrate that inhibition of estrogen-deficiency osteoporosis by ormeloxifene, as in case of estradiol, was mediated via inhibition of osteoclastogenesis, apoptosis of osteoclasts and up-regulation of TGF beta-3 expression. Raloxifene, though effective in inhibiting osteoclastogenesis in vitro at much lower concentrations, was not only less potent in preventing ovariectomy-induced bone loss in retired breeder female rats in vivo but also appeared to have a different mechanism of action than ormeloxifene and estradiol.

Lasofoxifene enhances vaginal mucus formation without causing hypertrophy and increases estrogen receptor β and androgen receptor in rats

OBJECTIVE

Lasofoxifene, a new selective estrogen-receptor modulator (SERM), shows efficacy in vaginal and vulvar atrophy in postmenopausal women. Here, we sought to explore the possible mechanisms of action for this effect in comparison with other SERMs using an immature ovariectomized rat model.

DESIGN

SERMs (lasofoxifene, raloxifene, and tamoxifen) and 17alpha-ethinyl estradiol were administered orally to immature ovariectomized rats daily for 1 or 4 days. Vaginal and uterine tissues were weighed and processed for histomorphometric measurements, vaginal mucopolysaccharide staining, and immunohistochemistry of 5-bromo-2'-deoxyuridine and steroid receptors. Receptor quantification was determined by a novel ultrasensitive enzyme-linked immunosorbent assay method.

RESULTS

Lasofoxifene and raloxifene showed a minimal increase in vaginal and uterine weight, epithelial cell proliferation, and epithelial thickness in comparison with estradiol and tamoxifen. Lasofoxifene significantly enhanced vaginal mucus formation in a dose-dependent manner. Vaginal progesterone receptor protein was increased fivefold by estradiol and all three SERMs tested. 17alpha-Ethinyl estradiol caused a significant decrease in estrogen receptor alpha, but no change with other treatments. Only lasofoxifene significantly increased vaginal estrogen receptor beta and androgen receptor protein levels.

CONCLUSIONS

These results demonstrated that lasofoxifene stimulated vaginal mucus formation without causing cell proliferation in the rat reproductive tract. These effects may be due to the increased vaginal estrogen receptor beta and androgen receptor levels. This cellular and molecular profile of lasofoxifene in the vagina may account for its efficacy in the treatment of vaginal and vulvar atrophy in postmenopausal women.

Effects of raloxifene therapy on plasma renin and aldosterone levels and blood pressure in postmenopausal women

OBJECTIVE

Blood pressure, which generally increases after menopause, is one of the best tools to characterize cardiovascular disease. The renin-aldosterone system plays a role in determining cardiovascular risk and the role of estrogen in the regulation of angiotensinogen gene expression and serum levels is well known. Raloxifene can induce endothelium-dependent vasodilation without affecting endothelium-independent vasorelaxation. The aim of the study was to investigate the effects of raloxifene on the renin-aldosterone system and blood pressure in postmenopausal women.

DESIGNS

Forty women, 54-59 years of age, in physiological menopause for 6 months to 4 years, were enrolled in the study and treated with raloxifene 60 mg/day for 6 months. All had blood pressure less than 130/85 mm Hg at the start of the study. The women were divided into two groups: the first (group A; 20 women) with normal blood pressure and the second (group B; 20 women) with previous high blood pressure treated with antihypertensive drugs, not angiotensin-converting enzyme inhibitors or angiotensin receptor blockers.

RESULTS

No significant changes in plasma renin activity (PRA) or plasma concentrations of aldosterone were observed between the two groups after 6 months of raloxifene use. There was a slight reduction in PRA (11+/-4% for group A and 13+/-5% for group B) and in plasma levels of aldosterone (3.6+/-0.5% and 4.6+/-0.5%, respectively) with respect to basal values, but neither change was statistically significant.

CONCLUSIONS

The results of the present study show that raloxifene at 60 mg/day dose is well tolerated and has no clinical impact on blood pressure, PRA or aldosterone in postmenopausal women.

Treating urogenital atrophy

Urogenital atrophy, although a frequently occurring symptom of aging for all women, is a condition often not thought of as a symptom of distress for older women or a sign of pelvic pathology requiring treatment by clinicians. Rather, many clinicians feel it is an expected consequence of aging, and older women themselves assimilate their lifestyle to the uncomfortable symptoms of dryness, irritation, itching and malodorous discharge. At times, when symptoms become intolerable with coitus, women will abandon sexual intercourse with their partners due to dyspareunia and not seek intervention to reverse the condition owing to embarrassment in raising this sensitive topic. When urogenital atrophy is diagnosed and the patient requests treatment, the gold standard intervention is estrogen, which can either be delivered systemically or vaginally. Since the Women's Health Initiative data, low-dose, vaginally delivered estrogen is recommended.

Drug bioactivation, covalent binding to target proteins and toxicity relevance

A number of therapeutic drugs with different structures and mechanisms of action have been reported to undergo metabolic activation by Phase I or Phase II drug-metabolizing enzymes. The bioactivation gives rise to reactive metabolites/intermediates, which readily confer covalent binding to various target proteins by nucleophilic substitution and/or Schiff's base mechanism. These drugs include analgesics (e.g., acetaminophen), antibacterial agents (e.g., sulfonamides and macrolide antibiotics), anticancer drugs (e.g., irinotecan), antiepileptic drugs (e.g., carbamazepine), anti-HIV agents (e.g., ritonavir), antipsychotics (e.g., clozapine), cardiovascular drugs (e.g., procainamide and hydralazine), immunosupressants (e.g., cyclosporine A), inhalational anesthetics (e.g., halothane), nonsteroidal anti-inflammatory drugs (NSAIDSs) (e.g., diclofenac), and steroids and their receptor modulators (e.g., estrogens and tamoxifen). Some herbal and dietary constituents are also bioactivated to reactive metabolites capable of binding covalently and inactivating cytochrome P450s (CYPs). A number of important target proteins of drugs have been identified by mass spectrometric techniques and proteomic approaches. The covalent binding and formation of drug-protein adducts are generally considered to be related to drug toxicity, and selective protein covalent binding by drug metabolites may lead to selective organ toxicity. However, the mechanisms involved in the protein adduct-induced toxicity are largely undefined, although it has been suggested that drug-protein adducts may cause toxicity either through impairing physiological functions of the modified proteins or through immune-mediated mechanisms. In addition, mechanism-based inhibition of CYPs may result in toxic drug-drug interactions. The clinical consequences of drug bioactivation and covalent binding to proteins are unpredictable, depending on many factors that are associated with the administered drugs and patients. Further studies using proteomic and genomic approaches with high throughput capacity are needed to identify the protein targets of reactive drug metabolites, and to elucidate the structure-activity relationships of drug's covalent binding to proteins and their clinical outcomes.

Safety profile of raloxifene as used in general practice in England: results of a prescription-event monitoring study

Raloxifene, a selective estrogen receptor modulator (SERM) licensed for the prevention of non-traumatic vertebral fractures in postmenopausal women at increased risk of osteoporosis, was launched in the UK in August 1998. The aim of the study was to monitor the safety of raloxifene prescribed in the primary care setting in England using prescription-event monitoring (PEM). Patients were identified by means of prescription data supplied by the Prescription Pricing Authority between September 1998 and November 2000. Demographic and clinical event data were collected from questionnaires posted to primary care physicians (GPs) at least 6 months after the date of the first prescription for each patient. Information on medical events, suspected adverse drug reactions (ADRs), reasons for stopping treatment, pregnancies, and causes of death was requested. Event rates [Incidence Densities (IDs): no. first reports /1000 patient-months of treatment] were calculated. Differences between IDs for events reported in month one (ID(1)) and months 2-6 (ID(2-6)) of treatment were examined. The cohort comprised 13,987 patients [median age 62 years (IQR 55,69); 99.8% female]. The major indication was osteoporosis (40.9%, n=5725). Flushing was the event with the highest ID in month 1 (22.8), reported most frequently by GPs as an ADR to raloxifene (67/461 reports) and as the reason for stopping (700/4592 reports). Events associated with starting treatment included flushing, malaise/lassitude, headache/migraine, nausea/vomiting, sweating, cramp, pain abdomen, dizziness, diarrhea, mastalgia and vaginal hemorrhage. Less common events reported during treatment included deep vein thrombosis (n=13), pulmonary embolism (n=13), thrombophlebitis (n=31) and visual disturbance (n=29). In this study, there were 122 (0.9%) confirmed deaths, of which 32 causes of death were unknown. This study shows that raloxifene is generally well tolerated when used in general practice in England. Potential signals of unrecognised ADRs requiring further evaluation included gastrointestinal adverse symptoms and vaginal hemorrhage. There were also a small number of reports of events associated with venous thromboembolism and visual disorders that require further investigation.

Effects of ospemifene and raloxifene on hormonal status, lipids, genital tract, and tolerability in postmenopausal women

OBJECTIVE

To compare ospemifene and raloxifene regarding their effects on hormones, lipids, genital tract, and tolerability in postmenopausal women.

DESIGN

A randomized, double-blind study in which 118 healthy postmenopausal women received 30 (n = 29), 60 (n = 30), or 90 mg (n = 30) of ospemifene or 60 mg (n = 29) of raloxifene for 3 months.

RESULTS

There were no significant differences in the baseline characteristics between study groups. In comparison with raloxifene, follicle-stimulating hormone levels decreased significantly more in the 90-mg ospemifene group and sex hormone-binding globulin levels increased more in all ospemifene groups. Total cholesterol and low-density lipoprotein cholesterol levels decreased more in raloxifene than in ospemifene groups, although the difference in low-density lipoprotein cholesterol between 90-mg ospemifene and raloxifene was not significant. Endometrial thickness did not change in any study group and endometrial biopsies showed atrophy in the majority of subjects at 3 months. All ospemifene groups demonstrated a clear estrogenic effect on the vaginal epithelium, as seen in Pap smears. This was in sharp contrast to the raloxifene group, which had no effect on the vaginal epithelium. Kupperman index decreased in all study groups during treatment. The adverse events were mild, mainly single cases, and no clustering of events was observed. There were no clinically significant abnormal findings in laboratory safety parameters.

CONCLUSIONS

Ospemifene, at the dose of 90 mg/day, was more estrogenic than raloxifene, as shown by changes in serum follicle-stimulating hormone and sex hormone-binding globulin levels. Neither agent stimulated endometrium, but in contrast to raloxifene, ospemifene had a clear estrogenic effect in the vagina. Further studies with ospemifene are needed in subjects with vaginal atrophy.

Fatal Venous Thromboembolism Associated with Antipsychotic Therapy

OBJECTIVE:

To describe the occurrence of pulmonary embolism (PE) as a rare adverse effect of clozapine that is treatable, but sometimes fatal, and survey the literature on the subject in the hope of increasing awareness of the potential danger that may result from drug interactions.

CASE SUMMARY:

A 47-year-old woman treated with clozapine and paroxetine was admitted to the hospital with dyspnea and swelling of the leg. The patient was diagnosed as having PE and was treated with intravenous heparin. On hospital day 7, sudden acute respiratory failure developed and the patient died. Postmortem examination confirmed the existence of massive PE.

DISCUSSION:

The woman had no identifiable risk factors other than receiving a combination of clozapine and paroxetine, with a demonstrated elevated clozapine blood concentration. Use of the Naranjo probability scale revealed a probable likelihood that the adverse reaction was drug related.

CONCLUSIONS:

The association of antipsychotic drugs and venous thromboembolism has been previously described, but is still a rare finding. This case highlights the importance of monitoring and possibly discontinuing treatment when venous thrombosis is suspected. There should be careful monitoring, especially in patients with risk factors for thrombosis. Finally, antidepressant—antipsychotic drug combinations can increase the risk of rare adverse effects, such as venous thromboembolism, even in the absence of other risk factors.

Osteopenia and osteoporosis in women with breast cancer

Osteopenia and osteoporosis are prevalent in women. Epidemiologic studies show that the risk of breast cancer is greater in postmenopausal women with higher bone mineral density (BMD). Standard treatments for breast cancer such as adjuvant chemotherapy or hormonal therapy can increase bone loss, and hence may increase the risk of osteoporosis. Premenopausal women treated with standard adjuvant chemotherapy frequently develop permanent ovarian failure, or early menopause. Ovarian failure is associated with accelerated bone loss, and bisphosphonates may mitigate this bone loss in women treated with adjuvant chemotherapy. Tamoxifen preserves BMD in postmenopausal women; however, in premenopausal women tamoxifen may increase bone loss. Anastrazole, an aromatase inhibitor, is approved for adjuvant treatment of postmenopausal women with early-stage, estrogen receptor-positive breast cancer. With a follow-up duration of less than 5 years, anastrazole-treated women experience increased fractures relative to those treated with tamoxifen. The management of osteopenia and osteoporosis in women with breast cancer generally does not differ from women without breast cancer. Adequate dietary calcium and vitamin D intake, encouraging weight-bearing exercise, and counseling about the relationship between smoking and alcohol and bone loss are all prudent recommendations for overall health and may lessen bone loss and the risk of subsequent osteoporosis. BMD should be measured in women with chemotherapy-induced ovarian failure, and in those on aromatase inhibitors. Bisphosphonates reduce the bone loss associated with chemotherapy-induced ovarian failure, and clinical trials evaluating third-generation bisphosphonates in women with chemotherapy-induced ovarian failure are underway. As many women with breast cancer will be long-term survivors, increasing recognition of maintaining skeletal health is important.

Effects of long-term administration of N-3 polyunsaturated fatty acids (PUFA) and selective estrogen receptor modulator (SERM) derivatives in ovariectomized (OVX) mice

We studied the beneficial effects of dietary consumption of n-3 polyunsaturated fatty acids (PUFA) and two selective estrogen receptor modulator (SERM) derivatives (SERM-I and SERM-II) and their combined effect on serum lipids, skin dermis and adipose layers, bone marrow adipogenesis, and cytokine secretion in mice. Two different ovariectomized (OVX) models were studied: treatment began immediately post-OVX in one and 3 months post-OVX in the other. Our results showed that n-3 PUFA and both SERMs decreased triglyceride levels in the serum, and that SERMs also decreased serum cholesterol levels while n-3 PUFA had no similar effect. SERMs had no effect on IL-6, IL-1 beta, or IL-10 levels, but they decreased ex vivo tumor necrosis factor (TNF-alpha). N-3 PUFA decreased secretion of non-induced IL-6 and TNF-alpha from cultured BMC and IL-1 beta levels in vivo (i.e., in bone marrow plasma), but its main effect was a significant elevation in the secretion of IL-10, a known anti-inflammatory cytokine. OVX-induced B-lymphopoiesis was not affected by LY-139481 (SERM-I) while LY-353381 (SERM-II) exhibited an estrogen-antagonistic effect in sham and OVX mice and elevated the amount of B-cells in bone marrow. Fish oil consumption prevented the elevation in B-lymphopoiesis caused by OVX, but had no curative effect on established augmented B-lymphopoiesis. This activity could be mediated via the elevation of IL-10 which was shown to suppress B-lymphopoiesis. Both SERMs and n-3 PUFA inhibited the increase in adipose tissue thickness caused by OVX in mice. Our results showed that n-3 PUFA, could prevent some of the deleterious outcomes of estrogen deficiency that were not affected by SERMs. We observed no significant beneficial effects of the combined administration of SERM-I, SERM-II, and PUFA on the studied parameters.The exact mechanism by which polyunsaturated fatty acids exert their activities is still not clear, but peroxisome proliferator-activated receptors (PPARs) might be involved in processes which are modulated by n-3 PUFA.

Effects of ospemifene, a novel SERM, on hormones, genital tract, climacteric symptoms, and quality of life in postmenopausal women: a double-blind, randomized trial

OBJECTIVE

Ospemifene, a novel selective estrogen receptor modulator, shows a potential for prevention and treatment of osteoporosis in postmenopausal women. We studied the effects of ospemifene on hormone levels, genital tract organs, climacteric symptoms, and quality of life.

DESIGN

A double-blinded study in which 160 postmenopausal women were randomly allocated to receive either ospemifene at three different daily doses (30, 60, or 90 mg) or placebo for 3 months.

RESULTS

No significant differences were observed among the study groups in clinical characteristics or parameters reflecting estrogen action at baseline. Ospemifene reduced follicle-stimulating hormone and insulin-like growth factor I levels, whereas estradiol failed to change at all, and luteinizing hormone was reduced only in the 90-mg group of ospemifene. In the vast majority of participants, the endometrium remained atrophic after 3 months of treatment with ospemifene. Although the rate of proliferative endometrium slightly increased in all groups, including placebo, no hyperplasia or bleeding occurred in any participant. Ospemifene had no effect on the appearance of proliferation marker Ki-67 in the endometrium as compared with placebo, and endometrial thickness increased by mean 0.4 to 0.6 mm (P < 0.01, P < 0.05 and P < 0.05 for 30, 60 and 90 mg ospemifene, respectively). Uterine volume slightly increased (8.4%-14.7%) in the ospemifene groups (P > 0.05), perhaps as a result of increased uterine blood flow. The most conspicuous finding was the significant estrogenic effect on vaginal epithelium, as evidenced by an increase in intermediate and superficial cells in repeat Pap smears. Ospemifene was not observed to aggravate climacteric symptoms or cause adverse events, nor did it suppress climacteric symptoms.

CONCLUSIONS

Ospemifene at daily doses of 30 to 90 mg did not stimulate endometrium or aggravate hot flashes but clearly had a rather strong estrogenic effect on the vaginal epithelium during a 3-month treatment period. Such effects would be advantageous if ospemifene were found to be effective in the long-term prevention of osteoporosis.

Constrained phytoestrogens and analogues as ERbeta selective ligands

A new series of ERbeta (ERbeta) selective ligands has been prepared. One of the compounds 6, structurally related to the phytoestrogen apigenin 4, displays a binding preference for ERbeta over ERalpha of over 40-fold. In addition to its binding selectivity, 6 was able to potently induce metallothionein (an ERbeta specific response in human SAOS-2 cells) while demonstrating low potency in an ERalpha dependant ERE-tk luciferase assay in MCF-7 cells. Such receptor and cell selectivity could make 6 a useful molecular probe for better understanding the role of ERbeta in mammalian physiology.

Update on the current use of hormonals as therapy in advanced breast cancer

Hormonal agents have a confirmed role in the management of postmenopausal women with receptor-positive advanced breast cancer. Until recently, tamoxifen has been the accepted agent for treating these patients. However, accumulating evidence suggests that the new antiaromatase agents will replace the antiestrogens as the preferable option in hormone-naive patients. Comparative trials indicate that the aromatase inhibitors, anastrozole and letrozole, and the aromatase inactivator, exemestane, have at least equivalent efficacy to tamoxifen with similar or superior tolerability. These agents are also more effective than the progestin, megestrol acetate, when studied in patients progressing on tamoxifen. The improved aromatase selectivity and high potency of these antiaromatase agents when compared with earlier agents have resulted in improved efficacy and tolerability. Additionally, no cross-resistance has been reported between the antiaromatase agents and tamoxifen or, in some instances, among the antiaromatase agents themselves. The role of antiaromatase agents will certainly expand in the near future to include not only treatment of metastatic breast cancer, but use in the adjuvant and neoadjuvant settings as well, and, ultimately, breast cancer prevention. The results of ongoing investigations are awaited with interest.

Raloxifene does not influence flow-mediated endothelium-dependent and endothelium-independent vasodilatation of osteopenic postmenopausal women

OBJECTIVE

The study was undertaken to evaluate whether raloxifene influences endothelium-dependent and endothelium-independent vasodilatation in women.

STUDY DESIGN

In a double-blind, placebo-controlled randomized study, 30 osteopenic but otherwise healthy postmenopausal women received either placebo (n = 15 with one dropout) or raloxifene (60 mg/d, n = 15). Brachial artery flow-mediated endothelium-dependent and endothelium-independent vasodilatation was evaluated by ultrasound before and after 6 months of treatment, along with lipid and glucose metabolism. Endothelium-dependent dilatation was evaluated after a 4-minute block of artery blood flow through a cuff insufflated at suprasystolic blood pressure. Endothelium-independent vasodilatation was evaluated after sublingual nitroglycerin administration (400 microg).

RESULTS

Placebo did not modify any vascular or metabolic parameter. Raloxifene significantly decreased low-density lipoprotein levels (4.60 +/- 0.18 mmol/L vs 3.94 +/- 0.30 mmol/L, P <.015) but did not modify endothelium-dependent (21.6% +/- 4.6% vs 20.6% +/- 3.8%) or endothelium-independent vasodilatation (26.3% +/- 5.1% vs 32.0% +/- 5.5%).

CONCLUSION

Prolonged administration of raloxifene does not influence endothelium-dependent and endothelium-independent vasodilatation of osteopenic but otherwise healthy postmenopausal women.

Raloxifene administration in post-menopausal women with osteoporosis: effect of different BsmI vitamin D receptor genotypes

BACKGROUND

The vitamin D receptor (VDR) gene polymorphism has been considered a factor influencing the effectiveness of the anti-osteoporotic treatments. The aim of this study was to correlate the effectiveness of raloxifene treatment in post-menopausal women with osteoporosis to BsmI VDR genotypes.

METHODS

Between January and August 2000, 75 Italian osteoporotic women were enrolled and treated with raloxifene at a dose of 60 mg/day. At entry and after 1 year of treatment, lumbar bone mineral density (BMD), serum osteocalcin (OC) and urinary creatinine-corrected free deoxypyridinoline (DPD) levels were evaluated. DNA was extracted from blood and analysed with restriction endonuclease BsmI for VDR gene.

RESULTS

After treatment, a significant increase in lumbar BMD and a significant reduction in serum OC and urinary DPD levels were observed. The percentage of change (mean +/- SD) in lumbar BMD, and in serum OC and urinary DPD levels was significantly different in homozygous bb (1.58 +/- 0.80, -5.15 +/- 2.36 and -7.71 +/- 2.89 for BMD, OC and DPD respectively) in comparison with BB (4.13 +/- 2.26, -13.59 +/- 4.68 and -15.16 +/- 4.65 for BMD, OC and DPD respectively) BsmI VDR genotypes. Heterozygous Bb VDR patients showed an intermediate percentage (mean +/- SD) of BMD, serum OC and urinary DPD change (2.49 +/- 1.54, -8.69 +/- 2.60 and -10.52 +/- 2.56 for BMD, OC and DPD respectively) not significantly different in comparison with homozygous BB and bb.

CONCLUSIONS

In post-menopausal women with osteoporosis the effectiveness of raloxifene treatment on bone metabolism seems to be controlled by different BsmI VDR genotypes.

Pharmacological actions of a novel, potent, tissue-selective benzopyran estrogen

We have identified a new benzopyran derivative, 3-(4-methoxy) phenyl-4-[[4-[2-(1-piperidinyl)ethoxy]phenyl]methyl]-2H-1-benzopyran-7-ol hydrochloride (CHF 4227), with improved in vivo estrogen agonist/antagonist effects. CHF 4227 binds with high affinity to the human estrogen receptor-alpha and -beta (dissociation constant K(i) = 0.017 and 0.099 nM, respectively). In immature rats, oral administration of CHF 4227 for 3 days inhibited the uterotrophic action of 17alpha-ethynyl estradiol (EE2) (ED(50) = 0.016 mg/kg. day); raloxifene was 25 times less potent as estrogen antagonist (ED(50) = 0.39 mg/kg. day), whereas both compounds were found to be devoid of uterotrophic activity. In line with its estrogen antagonist effect, CHF 4227 significantly prevented the development of dimethylbenz[a]anthracene (DMBA)-induced mammary tumors, the incidence being reduced from 87.5 to 26.3% 6 months after DMBA administration. In ovariectomized (OVX) rats treated orally for 4 weeks, CHF 4227 completely inhibited OVX effects on bone density (ED(50) = 0.003 mg/kg. day) and on serum osteocalcin levels. The protective effects on bone were comparable with those achieved with EE2, whereas raloxifene was less efficacious and 100 times less potent. CHF 4227 reduced serum cholesterol (ED(50) = 0.007 mg/kg. day) and had little to no stimulatory effects on uterine weight, uterine peroxidase activity, and endometrium epithelial thickness. In conclusion, CHF 4227 compares favorably in efficacy and potency with raloxifene in preventing bone loss and in antagonizing EE2 stimulation of the uterus. This profile along with the minimal uterine stimulation suggests a therapeutic advantage to CHF 4227 over EE2 or raloxifene for the treatment of postmenopausal women.

Raloxifene administration in women treated with gonadotropin-releasing hormone agonist for uterine leiomyomas: effects on bone metabolism

This prospective randomized, single-blind, placebo-controlled clinical trial was performed to evaluate the efficacy of raloxifene in preventing the bone loss associated with GnRH agonist (GnRH-a) administration. One hundred premenopausal women with uterine leiomyomas were treated with leuprolide acetate depot at a dosage of 3.75 mg/d for 28 d and then randomized into two groups to receive raloxifene hydrochloride at 60 mg/d (group A) or placebo (1 tablet/d; group B). Bone mineral density (BMD) and serum bone metabolism markers were evaluated at admission and after six treatment cycles. Posttreatment BMD differed significantly from baseline BMD in group B but not in group A. BMD was significantly higher in group A than in group B. In group A, serum osteocalcin and bone alkaline phosphatase levels and urinary deoxypyridinoline and pyrilinks-D excretion were unchanged vs. baseline. Differently, posttreatment concentrations of these bone turnover markers were significantly lower in group B compared with baseline and group A values. In conclusion, raloxifene prevents GnRH-a related bone loss in premenopausal women with uterine leiomyomas.

Cytochrome P450 3A4-mediated bioactivation of raloxifene: irreversible enzyme inhibition and thiol adduct formation

Raloxifene is a selective estrogen receptor modulator which is effective in the treatment of osteoporosis in postmenopausal women. We report herein that cytochrome P450 (P450)3A4 is inhibited by raloxifene in human liver microsomal incubations. The nature of the inhibition was irreversible and was NADPH- and preincubation time-dependent, with K(I) and k(inact) values estimated at 9.9 microM and 0.16 min(-1), respectively. The observed loss of P450 3A4 activity was attenuated partially by glutathione (GSH), implying the involvement of a reactive metabolite(s) in the inactivation process. Subsequently, GSH adducts of raloxifene were identified in incubations with human liver microsomes; substitution with GSH occurred at the 5- or 7-position of the benzothiophene moiety or at the 3'-position of the phenol ring, with the 7-glutathionyl derivative being most abundant based on LC/MS and NMR analyses. These adducts are postulated to derive from addition of GSH to raloxifene arene oxides followed by dehydration and aromatization. Alternatively, raloxifene may be oxidized to an extended quinone intermediate, which then is trapped by GSH conjugation. The bioactivation of raloxifene most likely is catalyzed by P450 3A4, since the formation of GSH adducts was almost abolished when liver microsomes were pretreated with ketoconazole or with an inhibitory anti-P450 3A4 IgG. The GSH adducts also were detected in incubations of raloxifene with rat or human hepatocytes, while the corresponding N-acetylcysteine adducts were identified in the bile and urine from rats treated orally with the drug at 5 mg/kg. Taken together, these data indicate that P450 3A4-mediated bioactivation of raloxifene in vitro is accompanied by loss of enzyme activity. The significance of these findings with respect to the clinical use of raloxifene remains to be determined.

Selecting Appropriate Pharmacotherapy for Patients with Osteoporosis: Holistic Risk—Benefit Analysis

In the US, the major pharmacotherapeutic approaches for the prevention or treatment of osteoporosis in women are estrogen-based hormone replacement therapy, selective estrogen receptor modulators, salmon calcitonin, bisphosphonates, calcium, and vitamin D. All of these treatments are beneficial in increasing bone mineral density and reducing fractures in patients with osteoporosis. However, each of the therapies possesses a unique mechanism of action and other potential benefits and side effects. Estrogen replacement therapy may lower the risk of cardiovascular disease, but it increases the risk of venous thromboembolism (VTE) and may increase the risk of breast cancer. Unopposed estrogen therapy is associated with increased risk for endometrial cancer, but the addition of progestins virtually eliminates this adverse event. The selective estrogen receptor modulator raloxifene is associated with positive cardiovascular effects and demonstrates a protective effect against some types of breast cancer. Like estrogen, raloxifene increases the risk of VTE. Salmon calcitonin has a strong analgesic effect and is not associated with any serious long-term adverse events, but some individuals may not be able to tolerate the nasal formulation. Bisphosphonates are associated with serious upper GI effects. The concomitant administration of calcium and vitamin D in all patients being treated for osteoporosis is generally recommended.

Selecting optimal treatment relies on an individualized risk–benefit analysis that takes into account the patient's medical history, concomitant diseases, current medications, general physical and mental well being, and personal feelings about the various therapies. Careful consideration of the various treatment options may lead to improved compliance and more effective management of osteoporosis.

Effect of 1 year of discontinuation of raloxifene or estrogen therapy on bone mineral density after 5 years of treatment in healthy postmenopausal women

The beneficial effects of hormone replacement therapy (HRT), selective estrogen receptor modulators (SERMs), or bisphosphonates in the prevention and treatment of osteoporosis in postmenopausal women have been well established. However, little is known about the effects of discontinuation of treatment on bone mineral density. We investigated the effect of 1 year of discontinuation of the SERM raloxifene (Ral; 60 mg and 150 mg), conjugated equine estrogen (CEE; 0.625 mg), and placebo after 5 years of treatment in a double-blind, randomized study. Thirty-eight of 59 healthy and hysterectomized postmenopausal women (mean age 55 years) completed the treatment and 1 year follow-up period. Lumbar spine and femoral neck bone mineral density (BMD) were performed with dual-energy X-ray absorptiometry, before, during, and at the end of treatment, as well as after 1 year of discontinuation of therapy. One year of discontinuation significantly reduced the mean lumbar spine BMD in the raloxifene- and estrogen-treated women (p < 0.05), whereas mean femoral neck BMD was reduced significantly only in women treated with 60 mg Ral (p < 0.05). The mean percentage change (+/-SD) in lumbar spine BMD was: CEE, -6.2% (+/-3.7%); Ral 60 mg, -2.4% (+/-2.4%); Ral 150 mg, -2.6% (+/-3.1%); and placebo, -1.6% (+/-4.3%). Our results show that 5 years of treatment with either Ral or CEE did not protect against bone loss after 1 year of withdrawal of therapy, and that the rate of bone loss was not significantly different from that of placebo-treated women.

Effects of 3-phenyl-4-[[4-[2-(1-piperidinyl)ethoxy]phenyl]methyl]- 2H-1-benzopyran-7-ol (CHF 4056), a novel nonsteroidal estrogen agonist/antagonist, on reproductive and nonreproductive tissue

We have discovered a new, nonsteroidal, estrogen agonist/antagonist, 3-phenyl-4-[[4-[2-(1-piperidinyl)ethoxy]phenyl] methyl]-2H-1-benzopyran-7-ol (CHF 4056). The aim of this study was to determine the effects of CHF 4056 on a series of parameters (body weight, uteri, serum cholesterol, and bones) that were previously shown to be sensitive to estrogens and to selective estrogen receptor modulators (SERMs). CHF 4056 is a benzopyran derivative that binds with high affinity to the human estrogen receptors alpha and beta (dissociation constant K(i) of 0.041 and 0.157 nM, respectively). In immature rats, CHF 4056 induced a full estrogen antagonism (half-maximal efficacious dose = 0.33 mg/kg x day p.o.) coupled with a lack of uterine stimulatory activity, whereas the structurally related SERM levormeloxifene demonstrated a maximal partial agonist effect of approximately 65% that of 17alpha-ethynyl estradiol (EE2). In ovariectomized (OVX) rats, CHF 4056 (0.1-1 mg/kg x day p.o. for 4 weeks) significantly reduced OVX-induced bone loss in the lumbar spine L1-4 and OVX-induced increase in serum osteocalcin. These protective effects on bone tissue were comparable with those of 0.1 mg/kg x day EE2. In the same experimental conditions, serum cholesterol was significantly lower in the CHF 4056-treated animals, compared with vehicle-treated OVX rats. In line with the results observed in immature rats, also in OVX rats CHF 4056 diverged dramatically from EE2 and levormeloxifene in its lack of significant estrogenic effects on uterine tissue. In conclusion, CHF 4056 is a new SERM that produces beneficial effects on bone and cholesterol levels, while maintaining antagonist effects on the uterus.

COPD and osteoporosis

Osteoporosis, with resulting fractures, is a significant problem in patients with advanced COPD. The etiology for the bone loss is diverse but includes smoking, vitamin D deficiency, low body mass index, hypogonadism, sedentary lifestyle, and use of glucocorticoids. Effective strategies to prevent bone loss and/or to treat osteoporosis include calcium and vitamin D, hormone replacement when indicated, calcitonin, and bisphosphonate administration. However, many patients remain undiagnosed until their first fracture because of the lack of recognition of the disease. With an increased awareness by pulmonologists and the increased use of preventive strategies, the impact of osteoporosis on those patients with COPD should decrease.

Extraintestinal Complications of Inflammatory Bowel Disease

Extraintestinal complications of inflammatory bowel disease (IBD) are often secondary to the underlying disease. Therefore, the first priority is to get active IBD into remission with medications, since surgery for IBD is not indicated for the treatment of extraintestinal complications. Symptoms of extraintestinal complications usually can be treated with simple agents; the treatment of patients with refractory symptoms and the use of more complex drug regimens should be done in cooperation with specialists on affected organ systems. Careful consideration of prescribed drugs is necessary because they may negatively influence the course of IBD.

Estrogen receptor beta-selective transcriptional activity and recruitment of coregulators by phytoestrogens

Estrogens used in hormone replacement therapy regimens may increase the risk of developing breast cancer. Paradoxically, high consumption of plant-derived phytoestrogens, particularly soybean isoflavones, is associated with a low incidence of breast cancer. To explore the molecular basis for these potential different clinical outcomes, we investigated whether soybean isoflavones elicit distinct transcriptional actions from estrogens. Our results demonstrate that the estrogen 17beta-estradiol effectively triggers the transcriptional activation and repression pathways with both estrogen receptors (ERs) ERalpha and ERbeta. In contrast, soybean isoflavones (genistein, daidzein, and biochanin A) are ERbeta-selective agonists of transcriptional repression and activation at physiological levels. The molecular mechanism for ERbeta selectivity by isoflavones involves their capacity to create an activation function-2 surface of ERbeta that has a greater affinity for coregulators than ERalpha. Phytoestrogens may act as natural selective estrogen receptor modulators that elicit distinct clinical effects from estrogens used for hormone replacement by selectively recruiting coregulatory proteins to ERbeta that trigger transcriptional pathways.