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Raloxifene relaxes rat pulmonary arteries and veins: roles of gender, endothelium, and antagonism of Ca2+ influx.

Chan YC, Leung FP, Yao X, Lau CW, Vanhoutte PM, Huang Y.

Department of Physiology, Faculty of Medicine, Chinese University of Hong Kong, Shatin, NT, Hong Kong. yu-huang cuhk.edu.hk.

Effects of raloxifene have been documented in the systemic circulation. However, its impact on the pulmonary circulation is unclear. The present study investigated the role of gender, endothelial modulation, and Ca(2+) channel in relaxations evoked by raloxifene in rat pulmonary arteries and veins. Vascular responses were studied on isolated pulmonary blood vessels mounted in a myograph and constricted by U46619 (9,11-dideoxy-11alpha,9alpha-epoxymethanoprostaglandin F(2alpha)). Constrictions to CaCl(2) were studied in Ca(2+)-free, 60 mM K(+) solution. Changes in the intracellular calcium ion concentration ([Ca(2+)](i)) in vascular smooth muscle were measured using a calcium fluorescence imaging method. Raloxifene was more effective in relaxing U46619-constricted pulmonary arteries from male than female rats. Raloxifene-induced relaxation was unaffected by ICI 182,780 [7alpha-[9-[(4,4,5,5,5,-pentafluoropentyl)-sulfinyl]nonyl]-estra-1,3,5(10)-triene-3,17beta-diol], inhibition of the nitric oxide (NO) pathway, or removal of the endothelium. In arteries without endothelium, raloxifene attenuated CaCl(2)-induced constriction and CaCl(2)-stimulated increase in [Ca(2+)](i) with similar potencies. Raloxifene caused endothelium-independent relaxations in pulmonary veins, albeit to a lesser degree than in pulmonary arteries. The venous responses showed a gender difference because raloxifene was more potent in male veins. In summary, raloxifene relaxed rat pulmonary arteries, and this effect did not involve the endothelium/NO or ICI 182,780-sensitive estrogen receptors. Raloxifene, like nifedipine, reduced constriction and [Ca(2+)](i) increase in response to CaCl(2) in high K(+) solution. Raloxifene also relaxed high K(+)-constricted pulmonary veins. Our data indicate that raloxifene acutely relaxes rat pulmonary blood vessels primarily via inhibition of Ca(2+) influx through voltage-sensitive Ca(2+) channels. Finally, raloxifene induced more relaxation in blood vessels isolated from male than female rats.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15550571&dopt=Abstract raloxifene Evista



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Health-economic comparison of three recommended drugs for the treatment of osteoporosis.

Brecht JG, Kruse HP, Mohrke W, Oestreich A, Huppertz E.

InForMed - Outcomes Research and Health Economics, Ingolstadt, Germany. jg.brecht informed.de

Osteoporosis is a large and growing disease with significant health consequences. Based on an evaluation of clinical evidence, the German osteology umbrella organization DVO (Dachverband Osteologie deutschsprachiger wissenschaftlicher Fachgesellschaften) published guidelines in March 2003 for the diagnosis and treatment of osteoporosis. For prevention of fractures in women with postmenopausal and senile osteoporosis, these guidelines recommend three treatment options as first-line therapy: risedronate, alendronate and raloxifene. No evidence is currently available for the reduction of hip fractures by raloxifene. Only risedronate and alendronate, therefore, are recommended for prevention of hip fractures. Information on the cost-effectiveness of preventing and treating osteoporosis may support decision makers in more efficient allocation of resources. Accordingly, the objective of this study is the comparative assessment of the cost-effectiveness of risedronate, alendronate and raloxifene for patient populations in Germany at high risk of osteoporotic fracture due to low bone mineral density (BMD) (i.e., T-score < -2.5) and resulting from a history of at least one previous vertebral fracture, as compared to osteoporotic patients with no treatment. Target variables for the economic comparison are costs per hip fracture avoided and costs per quality-adjusted life year (QALY) gained. Hip fractures are the most costly and best-documented complication of osteoporosis. A cost-effectiveness analysis was therefore conducted, using as criteria for evaluating intervention the incremental cost per hip fracture avoided and the cost per QALY gained. We used a fracture-incidence-based Markov model of osteoporosis, with analysis of patients' transition across outcome states over time (e.g., fracture, healthy, dead). Base-case analysis was conducted on a cohort of 1,000 women aged 70 with low spine BMD and prevalent vertebral fracture, over 3 years of treatment with risedronate, alendronate or raloxifene, and with application of a 10-year analytic time horizon. Model inputs included hip and vertebral fracture incidence rates; relative risk of fracture given low BMD and prevalent vertebral fracture, fracture cost, treatment prices/day (risedronate: 35 mg, 1.76 euro; alendronate: 70 mg, 1.82 euro; raloxifene: 60 mg, 1.82 euro); health utility; and efficacy in terms of relative-risk reduction of fracture of the hip (60% risedronate; 51% alendronate; not significant raloxifene) and vertebrae (49% risedronate; 47% alendronate; 30% raloxifene). A 5% discount rate was applied to cost and outcomes. In the base case, treatment with risedronate reduces costs from the social insurance perspective with respect to both endpoints: i.e., costs per averted hip fracture and QALY. Over the 3-year treatment period and 10-year observation, furthermore, risedronate proved superior to alendronate and raloxifene (i.e., risedronate was less expensive and more effective). From the perspective of statutory health insurance, the cost per averted hip fracture is 37,348 euro for risedronate and 48,349 euro for alendronate (costs for raloxifene were not calculated due to a nonsignificant effect on prevention of hip fractures); and cost per QALY gained is 32,092 euro for risedronate, in comparison to patients in Germany with no therapy (alendronate 41,302 euro; raloxifene 1,247,119 euro). This cost-effectiveness analysis gives evidence that bisphosphonates are cost effective. Under consideration of current prices and the published clinical evidence, risedronate dominates the comparison of DVO-recommended drugs.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15575171&dopt=Abstract raloxifene Evista



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Gene expression changes induced by estrogen and selective estrogen receptor modulators in primary-cultured human endometrial cells: signals that distinguish the human carcinogen tamoxifen.

Pole JC, Gold LI, Orton T, Huby R, Carmichael PL.

Cancer Genomics Program, Department of Pathology, Hutchison/MRC Research Centre, University of Cambridge, Cambridge CB2 2XZ, UK.

Tamoxifen has long been the endocrine treatment of choice for women with breast cancer and is now employed for prophylactic use in women at high risk from breast cancer. Other selective estrogen receptor modulators (SERMs), such as raloxifene, mimic some of tamoxifen's beneficial effects and, like tamoxifen, exhibit a complex mixture of organ-specific estrogen agonist and antagonistic properties. However, accompanying the positive effects of tamoxifen has been the emergence of evidence for an increased risk of endometrial cancer associated with its use. A more complete understanding of the mechanism(s) of SERM carcinogenicity and endometrial effects is therefore required. We have sought to compare and characterise the transcript profile of tamoxifen, raloxifene and the agonist estradiol in human endometrial cells. Using primary cultures of human endometria, to best emulate the in vivo responses in a manageable in vitro system, we have shown 230 significant changes in gene expression for epithelial cultures and 83 in stromal cultures, either specific to 17beta-estradiol, tamoxifen or raloxifene, or changed across more than one of the treatments. Considering the transcriptome as a whole, the endometrial responses to raloxifene or tamoxifen were more similar than either drug was to 17beta-estradiol. Treatment of endometrial cultures with tamoxifen resulted in the largest number of gene changes relative to control cultures and a high proportion of genes associated with regulation of gene transcription, cell-cycle control and signal transduction. Tamoxifen-specific changes that might point towards mechanisms for its proliferative response in the endometrium included changes in retinoblastoma and c-myc binding proteins, the APCL, dihydrofolate reductase (DHFR) and E2F1 genes and other transcription factors. Tamoxifen was also found to give rise to the highest number of gene expression changes common to those that characterise malignant endometria. It is anticipated that this study will provide leads for further and more focused investigation into SERM carcinogenicity.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15590111&dopt=Abstract raloxifene Evista



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Both estrogen and raloxifene protect against beta-amyloid-induced neurotoxicity in estrogen receptor alpha-transfected PC12 cells by activation of telomerase activity via Akt cascade.

Du B, Ohmichi M, Takahashi K, Kawagoe J, Ohshima C, Igarashi H, Mori-Abe A, Saitoh M, Ohta T, Ohishi A, Doshida M, Tezuka N, Takahashi T, Kurachi H.

Department of Obstetrics and Gynecology, Yamagata University, School of Medicine, 2-2-2 Iidanishi, Yamagata 990-9585, Japan.

Although estrogen is known to protect against beta-amyloid (Abeta)-induced neurotoxicity, the mechanisms responsible for this effect are only beginning to be elucidated. In addition, the effect of raloxifene on Abeta-induced neuro-toxicity remains unknown. Here we investigated whether raloxifene exhibits similar neuro-protective effects to estrogen against Abeta-induced neurotoxicity and the mechanism of the effects of these agents in PC12 cells transfected with the full-length human estrogen receptor (ER) alpha gene (PCER). Raloxifene, like 17beta-estradiol (E2), significantly inhibited Abeta-induced apoptosis in PCER cells, but not in a control line of cells transfected with vector DNA alone (PCCON). Since telomerase activity, the level of which is modulated by regulation of telomerase catalytic subunit (TERT) at both the transcriptional and post-transcriptional levels, is known to be involved in suppressing apoptosis in neurons, we examined the effect of E2 and raloxifene on telomerase activity. Although both E2 and raloxifene induced telomerase activity in PCER cells, but not in PCCON cells, treated with Abeta, they had no effect on the level of TERT expression. These results suggest that neither E2 nor raloxifene affects the telomerase activity at the transcriptional level. We therefore studied the mechanism by which E2 and raloxifene induce the telomerase activity at the post-transcriptional level. Both E2 and raloxifene induced the phosphorylation of Akt, and pre-treatment with a phosphatidylinositol 3-kinase inhibitor, LY294002, attenuated both E2- and raloxifene-induced activation of the telomerase activity. Moreover, both E2 and raloxifene induced both the phosphorylation of TERT at a putative Akt phosphorylation site and the association of nuclear factor kappaB with TERT. Our findings suggest that and raloxifene exert neuroprotective effects by E2 telomerase activation via a post-transcriptional cascade in an experimental model relevant to Alzheimer's disease.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15590986&dopt=Abstract raloxifene Evista



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Cost effectiveness of raloxifene in the treatment of osteoporosis in Sweden: an economic evaluation based on the MORE study.

Borgstrom F, Johnell O, Kanis JA, Oden A, Sykes D, Jonsson B.

Department of Learning, Informatics, Management and Ethics, Karolinska Institutet, Stockholm, Sweden. fredrik.b healtheconomics.se

BACKGROUND: The Multiple Outcomes of Raloxifene Evaluation (MORE) study showed that treatment with raloxifene reduces the risk of vertebral fracture and breast cancer in postmenopausal women with osteoporosis. OBJECTIVE: Based on the MORE study the aim of the present study was to assess the cost effectiveness of raloxifene (compared with no treatment) for the treatment of osteoporosis in postmenopausal women in Sweden. DESIGN: A revised version of a previously developed computer simulation model was used. The impact of the risk-reducing effect of raloxifene on vertebral fractures and breast cancer on cost effectiveness was analysed using a clinical and a morphometric definition of vertebral fracture. Benefits of raloxifene treatment were measured in quality-adjusted life-years (QALYs) and life-years gained. The study estimated the cost effectiveness mainly from a healthcare perspective but the cost effectiveness taking a societal perspective was also analysed. RESULTS: Intervention costs (in Swedish kronor [SEK] and euros [euro], year 2001 values) in postmenopausal women with a relative risk of vertebral fracture of 2 were SEK372000 (euro40000), SEK303000 (euro33000) and SEK263000 (euro28000) per QALY for women aged 60, 70 and 80 years, at start of treatment, respectively, when the clinical vertebral definition was used. The cost effectiveness using a clinical morphometric vertebral fracture definition was similar to the cost effectiveness using a clinical vertebral fracture definition. CONCLUSIONS: In relation to accepted threshold values for cost per QALY in Sweden, this model indicates, with its underlying assumptions and data, that raloxifene (compared with no treatment) is cost effective for the treatment of postmenopausal women at an increased risk of vertebral fracture, from the Swedish healthcare and societal perspectives.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15612833&dopt=Abstract raloxifene Evista



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Effect of raloxifene on activated protein C (APC) resistance in postmenopausal women and on APC resistance and homocysteine levels in elderly men: two randomized placebo-controlled studies.

Duschek EJ, Neele SJ, Thomassen MC, Rosing J, Netelenbos C.

Department of Endocrinology, VU University Medical Center, Amsterdam, The Netherlands. e.duschek vumc.nl

Raloxifene, a selective estrogen receptor modulator, like hormonal replacement therapy increases the risk of venous thromboembolism in postmenopausal women. A possible explanation for the increased thrombotic risk could be an increase in acquired resistance to activated protein C (APC). In two randomized, placebo-controlled, double-blind studies we determined the effect of raloxifene on the normalized APC sensitivity ratios (nAPCsr). The nAPCsr were determined with the thrombin generation-based APC resistance test. In the first study 83 postmenopausal women (age, 51.1 +/- 2.7 years) randomly received daily 0.625 mg conjugated equine estrogen and 2.5 mg medroxyprogesterone acetate (n=17), 60 mg raloxifene (n=23), 150 mg raloxifene (n=20) or placebo (n=23) for 24 months. At baseline and after 6, 12 and 24 months the nAPCsr were measured. In the second study 30 elderly men (age, 64.4 +/- 2.4 years) randomly received 120 mg raloxifene (n=15) or placebo (n=15) for 3 months. At baseline and after 3 months the nAPCsr and fasting homocysteine levels were measured. In postmenopausal women conjugated equine estrogen/medroxyprogesterone acetate significantly increased the nAPCsr from 1.26 +/- 0.82 to 2.87 +/- 0.86 at 24 months (P <0.0005 compared with placebo). Raloxifene had no significant effect on nAPCsr compared with placebo in both women and men. The results did not change after excluding carriers of factor V Leiden. Also fasting homocysteine levels were not affected by raloxifene in the aging men. It is concluded that raloxifene, in contrast to combined hormonal replacement therapy, does not increase APC resistance.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15613919&dopt=Abstract raloxifene Evista