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Environmental fate and chemistry of raloxifene hydrochloride.

Teeter JS, Meyerhoff RD.

Lilly Research Laboratories, Division of Eli Lilly and Company, Greenfield, Indiana 46140, USA. jsteeter lilly.com

Raloxifene hydrochloride is a selective estrogen receptor modulator (SERM) used for the prevention and treatment of osteoporosis in women. Excretion of raloxifene occurs through the feces of patients. Raloxifene has the potential to be discharged into waste treatment systems after therapeutic use. Raloxifene hydrochloride was investigated using a battery of studies designed to describe its physical/chemical characteristics and define its fate in the environment. The mean measured solubility of raloxifene hydrochloride (+/- standard deviation) was 345.2 +/- 15.6 microg/ml, 13.3 +/- 0.6 microg/ml, 0.9224 +/- 0.015 microg/ml, and 627.4 +/- 132.0 microg/ml in aqueous buffers at pH 5, 7, and 9 and in unbuffered water, respectively. Raloxifene exhibited a mean molar absorptivity of 34,000 and a wavelength absorbance maximum at 287 nm for pH 5 and 7 aqueous buffer solutions and 297 nm at pH 9. Mean measured Kow values were 516 +/- 17, 1,323 +/- 91, and 1,556 +/- 135 at pH 5, 7, and 9, respectively. After 5 d at 50 degrees C, raloxifene hydrolyzed 8.02, 10.61, and 23.81% in pH 5, 7, and 9 aqueous buffers, respectively. In a 28-d hydrolysis study at 25 degrees C, the calculated first-order hydrolysis rates were 6.92 x 10(-4), 1.70 x 10(-3), and 7.66 x 10(-3)/d, and the corresponding half-lives were 1,001, 410, and 90 d in pH 5, 7, and 9 aqueous buffers, respectively. Raloxifene sorbed significantly to sewage treatment solids with Freundlich isotherm adsorption coefficients K between 2,000 and 3,000. Raloxifene degraded rapidly in the presence of sewage solids. In a system containing 0.470 g/L sludge solids, the raloxifene biodegradation rate and half-life were 0.0966/h and 7.17 h, respectively. In a 28-d aerobic-aquatic biodegradation study containing 30 mg/L sludge solids, the raloxifene biodegradation rate and half-life were 0.0188/d and 37 d, respectively. Given the fate and behavior of raloxifene in these studies, it is anticipated that raloxifene would rapidly dissipate in the environment.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11951945&dopt=Abstract raloxifene Evista



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Estradiol and raloxifene decrease the formation of multinucleate cells in human bone marrow cultures.

Ramalho AC, Couttet P, Baudoin C, Morieux C, Graulet AM, de Vernejoul MC, Cohen-Solal ME.

INSERM U. 349, Lariboisiere Hospital, 2, rue Ambroise-Pare, 75475 Paris Cedex 10 France.

Estrogen (E2) deficiency is responsible for increased bone turnover in the postmenopausal period, and it can be prevented by estrogen replacement therapy. The way estrogen acts on bone cells is not fully understood. Human bone marrow cell cultures may be a reliable model for studying the action of steroids on osteoclastogenesis in vitro. We examine the effects of estradiol and Raloxifene, a selective estrogen receptor modulator, on human primary bone marrow cells cultured for 15 days. 17beta-estradiol and Raloxifene significantly decreased the number of tartrate-resistant acid phosphatase multinucleate cells from osteoclast precursors on day 15. Estrogen receptor alpha (ER-alpha) mRNA was present in bone marrow mononuclear cells cultured for 5 days, but there was no estrogen receptor beta (ER-beta) mRNA, suggesting that this effect was mediated by ER-alpha. 15-day cultures no longer contained ER-alpha mRNA, suggesting that estrogen acts on early events of osteoclast differentiation. Finally, 10-8 M 17beta-estradiol has no effect on the release of IL-6 and IL-6-sr into the medium of marrow mononuclear cells cultured for 5 or 15 days. Osteoclast apoptosis was not affected by estradiol or Raloxifene after 15 days of culture under our conditions. In conclusion, we have shown that both estradiol and Raloxifene inhibit osteoclast differentiation in human bone marrow mononuclear cultures. The biological effect that can mimic in vivo differentiation could be mediated through ER-alpha.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11956019&dopt=Abstract raloxifene Evista



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The effect of raloxifene on the incidence of ovarian cancer in postmenopausal women.

Neven P, Goldstein SR, Ciaccia AV, Zhou L, Silfen SL, Muram D.

Department of Obstetrics and Gynecology, Algemene Kliniek St.-Jan, Broekstraat 114, B-1000 Brussels, Belgium. Patrick.neven uz.kuleuven.ac.be

OBJECTIVE: The aim of this study was to determine the incidence of ovarian cancer in postmenopausal women treated with raloxifene compared with placebo. METHODS: This analysis comprises integrated data from seven randomized, placebo-controlled trials of raloxifene (N = 9837). Ovarian cancer cases were identified from the safety database and reviewed by a gynecologic adjudication review board. RESULTS: Sixteen cases of ovarian cancer were reported: 8 women (79.4/100,000 patient-years) on placebo and 8 (37.4/100,000 patient-years) on pooled raloxifene doses. The relative risk of ovarian cancer associated with raloxifene therapy was 0.50 (95% confidence interval, 0.19-1.35). CONCLUSION: Raloxifene use was not associated with an increased risk for ovarian cancer. (c) 2002 Elsevier Science (USA).

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11972407&dopt=Abstract raloxifene Evista



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Adrenal function under long-term raloxifene administration.

Genazzani AR, Lombardi I, Borgioli G, di Bono I, Casarosa E, Gambacciani M, Palumbo M, Genazzani AD, Luisi M.

Department of Reproductive Medicine and Child Development, Division of Obstetrics and Gynecology, University of Pisa, Pisa, Italy.

The aim of the present study was to evaluate the effect of long-term (12 months) administration of raloxifene hydrochloride (60 mg/day) on the steroid production of the adrenal cortex and on the hypothalamic-pituitary-adrenal axis in postmenopausal women. We performed a basal evaluation, a corticotropin releasing factor (CRF) (100 microg i.v. bolus) test and a dexamethasone (DXM) (0.25 mg) suppression-adrenocorticotropic hormone (ACTH) (10 microg i.v. bolus) stimulation test in 11 postmenopausal women, before and after 3, 6 and 12 months of raloxifene treatment. Raloxifene administration significantly modified circulating levels of adrenal steroids, decreasing cortisol (-24%), dehydroepiandrosterone (DHEA) (-36%), and its sulfate (DHEAS) (-41%), and androstenedione (-29%), and increasing circulating allopregnanolone (+39%) levels. Progesterone and 17OH-progesterone levels remained unmodified, while estradiol and estrone levels showed a significant decrease (-51% for estradiol and -61% for estrone). We also observed an increase in circulating ACTH (+58%) and beta-endorphin (+120%). No modifications in the hormonal responses to CRF were observed during the treatment. DXM significantly suppressed circulating steroids at any time with a lower suppression of cortisol from the third month and a higher suppression of DHEA at 12 months. ACTH administration was associated with a significantly blunted cortisol response from the sixth month and a significantly increased response of allopregnanolone from the third month. The present data exclude a raloxifene effect on pituitary sensitivity to CRF and demonstrate a reduced adrenal sensitivity to ACTH, sustained by the opposite changes in basal cortisol and Delta5 androgens, which were reduced, and in ACTH and beta-endorphin, which were increased, as well by the reduced response of cortisol to the direct ACTH stimulus. The reduction of circulating cortisol levels and cortisol response to the ACTH challenge suggests that raloxifene protects against the neurotoxic effects of endogenous glucocorticoids. Furthermore, the progressive increase in basal allopregnanolone and its increased response to ACTH indicate that chronic raloxifene administration exerts direct effects on the pattern of adrenal enzymes, leading to specific changes in the circulating levels of this anxiolytic progesterone metabolite. The important reduction in the circulating levels of estradiol and estrone under long-term raloxifene administration may represent a further mechanism by which this molecule may exert a protective effect against breast and endometrial malignancies.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12737677&dopt=Abstract raloxifene Evista



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Mechanism of raloxifene-induced relaxation in femoral veins depends on ovarian hormonal status.

Bracamonte MP, Rud KS, Miller VM.

Department of Physiology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.

Experiments were designed to study effects of raloxifene, a selective estrogen receptor modulator, on venous endothelium and smooth muscle. Rings of femoral veins with and without endothelium from adult gonadally intact, and ovariectomized female pigs were suspended for measurement of isometric force in organ chambers. Concentration-response curves to raloxifene (10-9-10-5 M) were obtained in rings at baseline tension or following contraction with prostaglandin (2 x 10-6 M) in the absence or presence of NG-monomethyl-l-arginine (l-NMMA) (nitric oxide synthase inhibitor), 1H-(1.2.4) oxadiazolo (4,3-A) quinoxalin-1-one (ODQ, soluble guanylate cyclase inhibitor), tetraethylammonium acetate (TEA; potassium channel blocker), or indomethacin (cyclooxygenase inhibitor). Raloxifene caused acute, concentration-dependent relaxations that were greater in rings with than in rings without endothelium from both groups. The l-NMMA significantly inhibited relaxations to raloxifene in rings with endothelium from ovariectomized females whereas TEA only inhibited relaxations in rings with endothelium from intact female pigs. ODQ and indomethacin significantly inhibited relaxations in rings with endothelium from both groups. These results suggest that raloxifene acutely relaxes femoral veins through release of endothelium-derived factors and by direct stimulation of vascular smooth muscle cells. Whether nitric oxide or potassium channel activation contributes to relaxations by raloxifene may depend on ovarian hormonal status of the animal.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11973414&dopt=Abstract raloxifene Evista



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Raloxifene improves endothelial dysfunction in hypertension by reduced oxidative stress and enhanced nitric oxide production.

Wassmann S, Laufs U, Stamenkovic D, Linz W, Stasch JP, Ahlbory K, Rosen R, Bohm M, Nickenig G.

Medizinische Klinik und Poliklinik, Innere Medizin III, Universitatskliniken des Saarlandes, Homburg/Saar, Germany.

BACKGROUND: It has not been completely clarified whether selective estrogen receptor modulators (SERMs) such as raloxifene exert vasoprotective effects similar to those of estrogens. METHODS AND RESULTS: To investigate vascular effects of raloxifene, male spontaneously hypertensive rats were treated for 10 weeks with either raloxifene (10 mg x kg(-1) x d(-1)) or vehicle. Raloxifene improved endothelium-dependent vasodilatation but had no effect on either endothelium-independent vasorelaxation or phenylephrine-induced vasoconstriction. Raloxifene treatment increased the release of NO from the vessel wall by enhanced expression and activity of endothelial NO synthase. Blood pressure reduction after bradykinin infusion was more pronounced in animals treated with SERMs. The production of superoxide in intact aortic segments was decreased by raloxifene treatment. Administration of raloxifene had no effect on the expression of the essential NAD(P)H oxidase subunits p22phox and nox1 in the vasculature but reduced the activity and expression of vascular membrane-bound rac1, a GTPase required for the activation of the NAD(P)H oxidase. Finally, blood pressure levels were significantly decreased in spontaneously hypertensive rats treated with raloxifene. All SERM effects were also detected in healthy age-matched Wistar rats. In cultured rat aortic vascular smooth muscle cells, raloxifene inhibited angiotensin II-induced reactive oxygen species production dependent on estrogen receptor activation. CONCLUSIONS: Raloxifene treatment improves hypertension-induced endothelial dysfunction by increased bioavailability of NO. This is achieved by an increased activity of endothelial NO synthase and by an estrogen receptor-dependent reduction in release of reactive oxygen species from vascular cells. These vascular effects cause a profound blood pressure reduction and lead to decreased vascular damage in male spontaneously hypertensive rats.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11980689&dopt=Abstract raloxifene Evista