- Email: [email protected]
Randomized control study of the effects of raloxifene on serum lipids and homocysteine in older women
Randomized control study of the effects of raloxifene on serum lipids and homocysteine in older women Vincenzo De Leo, MD,a Antonio la Marca, MD,a Giuseppe Morgante, MD,a Danila Lanzetta, MD,a Carlo Setacci, MD,b and Felice Petraglia, MDa Siena, Italy OBJECTIVE(S): Raloxifene, a selective estrogen receptor modulator, has beneficial estrogen agonist effects on bone and cardiovascular risk factors and estrogen antagonist effects on the breast and uterus. Limited clinical data have shown a sustained decrease in total cholesterol, low-density lipoprotein cholesterol, and homocysteine levels; an elevated homocysteine level is an independent risk factor for atherosclerosis. All of these studies were conducted in relatively young populations of women (mean age, 52-54 years). Raloxifene does not affect hot flushes, a major immediate symptom of menopause. This drug may therefore be useful in older women to prevent osteoporosis and cardiovascular disease. The aim of this clinical study was to evaluate the effects of raloxifene on plasma lipids and homocysteine in older women. STUDY DESIGN: The subjects were 45 healthy postmenopausal women, aged 60 to 70 years. The women were randomly assigned to therapy with raloxifene or placebo, 60 mg/d for 1 year. Twenty-six women received raloxifene and 19 received placebo. Checkups were performed every 3 months. At baseline and after 3, 6, 9, and 12 months of treatment we measured homocysteine, total serum cholesterol, triglycerides, and both high-density lipoprotein and low-density lipoprotein cholesterol. RESULTS: An effect on lipids was evident by 3 months with no significant additional modification at 12 months. Mean low-density lipoprotein cholesterol levels were lowered by 15% and total cholesterol was lowered by 8.5%. No reduction in high-density lipoprotein cholesterol or triglycerides was observed. After 3 months of therapy, homocysteine was significantly lower than at baseline (9.9 ± 1.6 vs 11 ± 2.1 µmol/L; P < .05). The greatest reduction with respect to baseline was reached after 6 months of therapy (–19.5% ± 3%; P < .05). CONCLUSION(S): The results of our study show that raloxifene at a dose of 60 mg/d reduces serum concentrations of low-density lipoprotein cholesterol and total cholesterol in healthy older women. Our study shows that in older women raloxifene leads to a 19.5% ± 3% reduction in fasting homocysteine levels. Raloxifene may have a favorable effect on the incidence of cardiovascular disease in older women. (Am J Obstet Gynecol 2001;184:350-3.)
Key words: Raloxifene, older women, lipids, homocysteine
Estrogen replacement therapy, with or without progesterone, is associated with a reduction in the risk for osteoporosis,1 cardiovascular disease,2 and overall mortality.3 However, there are undesirable effects associated with estrogen therapy that reduce patient compliance; they include resumption of menses, mastodynia, and a perceived increased risk for uterine and breast cancer.4, 5 SERMS, a novel class of selective estrogen receptor modulators, have potential as viable alternatives to estrogen in hormone replacement therapy. Raloxifene, a nonsteroid benzothiophene SERM, has beneficial estrogen From the Department of Obstetrics and Gynecology and the Department of Vascular Surgery, University of Siena. Received for publication April 24, 2000; revised June 6, 2000; accepted August 22, 2000. Reprint requests: Vincenzo De Leo, MD, Department of Obstetrics and Gynecology, University of Siena, Policlinico Le Scotte, Viale Bracci, 53100 Siena (SI), Italy. E-mail: [email protected]. Copyright © 2001 by Mosby, Inc. 0002-9378/2001 $35.00 + 0 6/1/111065 doi:10.1067/mob.2001.111065
350
agonist effects on bone5, 6 and cardiovascular risk factors7 and estrogen antagonist effects on the breast and uterus. Limited clinical data5-7 have shown a rapid and sustained decrease in total and low-density lipoprotein (LDL) cholesterol levels similar to that seen with hormone replacement therapy. Raloxifene has been shown to reduce plasma concentrations of homocysteine, an independent risk factor for atherosclerosis and thromboembolic disease.8, 9 Studies concerning homocysteine were conducted with relatively young populations of women (for reference 8, mean age, 54 years; for reference 9, range of 45-72 years with an average of 10 years past menopause). Raloxifene, however, does not affect hot flushes, a major immediate symptom of menopause. This drug may therefore be useful in older women to prevent osteoporosis and cardiovascular disease. The aim of the current clinical study was to evaluate the effects of raloxifene on plasma lipids and homocysteine in older women.
De Leo et al 351
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Material and methods The subjects were 45 healthy postmenopausal women, aged 60 to 70 years. Postmenopausal status was confirmed by follicle-stimulating hormone levels of at least 40 IU/L and estradiol levels <40 pg/mL (147 pmol/L). Exclusion criteria were recent thromboembolism, history of breast carcinoma, renal dysfunction, use of lipid-lowering drugs, and use of sex steroids more recently than 1 year before the start of the study. Informed consent was obtained from all subjects. The women were randomly assigned (by a random number table with an assignment criterion of 4 subjects to treatment and 3 subjects to placebo) to therapy with raloxifene 60 mg/d or placebo for 1 year. Twenty-six women received raloxifene and 19 received placebo. All women took oral calcium carbonate (500 mg/d elemental calcium) throughout the study. Checkups were performed every 3 months. At baseline and after 3, 6, 9, and 12 months of treatment we measured homocysteine, total serum cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides. LDL cholesterol was calculated by the Friedewald formula (LDL cholesterol = Total cholesterol – HDL cholesterol – Triglycerides × 0.2). At baseline and after 6 and 12 months the double-layer thickness of the uterine endometrium was determined by transvaginal ultrasonography (Sonoline SL-2; Siemens, Milan, Italy) performed by the same physician (Antonio la Marca). Compliance was assessed by interview at the end of treatment. No patients dropped out of the study. For the assays 3 mL of whole blood was drawn into a Vacutainer blood-collecting tube containing ethylenediaminetetraacetic acid (EDTA), cooled on ice, and immediately centrifuged at 1000g for 5 minutes at 4°C. Total homocysteine was determined by high-performance liquid chromatography with fluorescence detection according to the method of Araki and Sako,10 using a Kontron 320 (Kontron Instruments, Milan, Italy) system. The fluorescence intensities were measured with a Kontron SFM 25 (Kontron Instruments) fluorescence spectrophotometer. Statistical analysis. The results were expressed as mean ± SD. Non–Gaussian-distributed variables were transformed logarithmically before analysis. For clarity, non– log-transformed data are presented in Table I and Figs 1 and 2. The results were analyzed by analysis of variance with the Mann-Whitney test and the Student t test. Statistical significance was taken at P < .05. Results The demographic details of the study population are shown in Table I. Subjects were 60 to 70 years old and were an average of 17.5 years past menopause. There were no significant differences in age, body mass index, lipid levels, and homocysteine levels between the treated and placebo groups. As shown in Fig 1, an effect on lipids was evident by 3 months with no significant additional
Table I. Demographic details of study population
Age (y) Body mass index (kg/m2) Follicle-stimulating hormone (IU/L) Estradiol (pg/mL) Total cholesterol (mg/dL) LDL cholesterol (mg/dL) HDL cholesterol (mg/dL) Triglycerides (mg/dL) Homocysteine (µmol/L)
Raloxifene (n = 26)
Placebo (n = 19)
66 ± 3 24 ± 4.4 58 ± 8 15 ± 4 225 ± 53 138 ± 29 65 ± 17 110 ± 23 11 ± 2.1
65 ± 4 23 ± 5.2 61 ± 9 15 ± 5 218 ± 46 135 ± 27 62 ± 16 105 ± 21 11.5 ± 2.3
modification at 12 months. Mean LDL cholesterol levels were lowered by 15%, and total cholesterol levels were lowered by 8.5%. No reduction in HDL cholesterol or triglycerides was observed. After 3 months of therapy the homocysteine level was significantly lower than at baseline (9.9 ± 1.6 vs 11 ± 2.1 µmol/L; P < .05). The greatest reduction with respect to baseline was reached after 6 months of therapy (–19.5% ± 3%; P < .05; Fig 2). The median baseline endometrial thickness ranged from 1.6 to 2.3 mm in each group. There was no difference in endometrial thickness between groups at any time during the study. Comment Raloxifene is a benzothiophene derivative with which relatively much experience has been gained. It has beneficial estrogen agonist effects on bone and cardiovascular risk factors, but estrogen antagonist effects on the endometrium. It does not improve hot flushes but could be used in older women; however, few such studies have as yet been conducted. The results of our study show that raloxifene at a dose of 60 mg/d reduces serum concentrations of LDL cholesterol and total cholesterol in healthy women, without modifying levels of HDL cholesterol and triglycerides. These results confirm previous reports. It is thought that raloxifene reduces LDL cholesterol levels by enhancing LDL clearance by induction of hepatic LDL receptors.11, 12 However, raloxifene does not appear to have full agonist activity against the target(s) that estrogen modulates the increase in HDL cholesterol. Homocysteine is an independent risk factor for premature vascular disorders, including coronary,13 cerebrovascular,14 and peripheral vascular15 disease. The results of a prospective study by US physicians16 suggest that moderate serum levels of homocysteine are associated with an increased risk of premature vascular disorders. When they were compared with control subjects who were matched for age and smoking habits, subjects who previously had a myocardial infarction had significantly higher basal plasma concentrations of homocysteine.
352 De Leo et al
February 2001 Am J Obstet Gynecol
A
B
C
D
Fig 1. Percent changes from baseline in LDL cholesterol (A), total cholesterol (B), HDL cholesterol (C), and triglycerides (D) after placebo (circles) or raloxifene (squares) treatment. Asterisk, P < .05.
Fig 2. Percent changes from baseline in homocysteine levels after placebo (circles) or raloxifene (squares) treatment. Asterisk, P < .05.
There are indications that plasma homocysteine is related to estrogen status. Premenopausal women have lower plasma homocysteine levels than men and postmenopausal women17 and plasma homocysteine decreases in menopausal women on a regimen of estrogen replacement therapy.18 Plasma homocysteine levels are partly genetically determined,19 but acquired states such as cobalamine and folate deficiencies and renal failure may increase them.
Folate (as methyltetrahydrofolate) is required for methylation of homocysteine to methionine catalyzed by methionine synthase with vitamin B12 as cofactor. Blood levels of homocysteine are inversely related to blood levels of folate, vitamin B12, and vitamin B6.20 Several randomized controlled trials have shown that dietary supplements of folic acid lowered homocysteine levels.21, 22 A significant reduction in basal homocysteine in healthy postmenopausal women has been reported after hormone replacement therapy.7, 18, 23 Tamoxifene, a firstgeneration SERM, has been reported to reduce plasma homocysteine levels, and there is evidence that long-term treatment of patients with breast cancer with tamoxifene is associated with reduced cardiovascular mortality.24 It has recently been demonstrated that raloxifene decreases fasting plasma levels of homocysteine in a doserelated manner. Plasma homocysteine levels were significantly decreased with raloxifene 150 mg/d but not with raloxifene 60 mg/d.8 Another study concluded that hormone replacement therapy and raloxifene (60 and 120 mg/d) lower serum homocysteine levels to a comparable extent in postmenopausal women.9 Our study shows that in older women 60 mg/d leads to a 19.5% ± 3% reduction in fasting homocysteine levels. In a recent study25 we showed that folic acid supplements reduced plasma levels of homocysteine in postmenopausal women and that women with the highest ini-
De Leo et al 353
Volume 184, Number 3 Am J Obstet Gynecol
tial levels of homocysteine showed the greatest reduction after therapy. It is probable that higher basal levels of homocysteine in the women of our study with respect to the study by Mijatovic et al8 could explain the statistically significant reduction in homocysteine levels after raloxifene therapy in our results. The favorable preclinical effects of raloxifene on the cardiovascular system include inhibition of atherogenesis in cholesterol-fed rabbits, lowering of total cholesterol in ovariectomized rats and inhibition of LDL oxidation in vitro, inhibition of intimal thickening in carotid arteries of injured rats, increased endothelial cell basal nitric oxide availability, increased human umbilical vein endothelial cell thrombomodulin, and inhibition of vascular smooth muscle cell migration (for review see reference 26). Taken together with the preclinical findings, the results of our study suggest that raloxifene may have a favorable effect on the incidence of cardiovascular disease in older women.
10.
11.
12.
13. 14.
15.
16.
17. REFERENCES
1. Kiel DP, Felson DT, Anderson JJ, Wilson PWF, Moskowitz MA. Hip fracture and the use of estrogen in postmenopausal women. N Engl J Med 1987;317:1169-74. 2. Grodstein F, Stampfer MJ, Manson JE, Colditz GA, Willett WC, Rosner B, et al. Postmenopausal estrogen and progestin use and the risk of cardiovascular disease. N Engl J Med 1996;335:453-61. 3. Grodstein F, Stampfer MJ, Colditz GA, Willet WC, Manson JE, Joffe M, et al. Postmenopausal hormone replacement therapy and mortality. N Engl J Med 1997;336:1769-75. 4. Hulley S, Grady D, Bush T, Furberg C, Herrington D, Riggs B, et al. Randomized trial of estrogen plus progestin for secondary prevention of coronary heart disease in postmenopausal women. Heart and Estrogen/Progestin Replacement Study (HERS) Research Group. JAMA 1998;280:605-13. 5. Delmas PD, Bjarnason NH, Mitlak BH, Ravoux A, Shah AS, Huster WJ, et al. The effect of raloxifene on bone mineral density, serum cholesterol, and uterine endometrium in postmenopausal women. N Engl J Med 1997;337:1641-7. 6. Walsh BW, Kuller LH, Wild RA, Paul S, Farmer M, Lawrence JB, et al. Effects of raloxifene on serum lipids and coagulation factors in healthy postmenopausal women. JAMA 1998;279: 1445-51. 7. Draper MW, Flowers DE, Huster WJ, Neild JA, Harper KD, Arnaud C. A controlled trial of raloxifene (LY139481) HCL: impact on bone turnover and serum lipid profile in healthy, postmenopausal women. J Bone Miner Res 1996;11:835-42. 8. Mijatovic V, Netelenbos C, van der Mooren MJ, de Valk-de ROO GW, Jakobs C, Kenemans P. Randomized, double-blind, placebocontrolled study of the effects of raloxifene and conjugated equine estrogen on plasma homocysteine levels in healthy postmenopausal women. Fertil Steril 1998;70:1085-9. 9. Walsh BW, Paul S, Wild RA, Dean RA, Tracy RP, Cox DA, et al. The effects of hormone replacement therapy and raloxifene on
18.
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26.
C-reactive protein and homocysteine in healthy postmenopausal women: a randomized, controlled trial. J Clin Endocrinol Metab 2000;85:214-8. Araki A, Sako Y. Determination of free and total homocysteine in human plasma by high-liquid chromatography with fluorescence detection. J Chromatogr 1987;422:43-52. Windler E, Kovanen PT, Chao YS, Brown MS, Havel RJ, Goldstein JL. The estradiol-stimulated lipoprotein receptor of rat liver. J Biol Chem 1980;255:10464-71. Ma PTS, Yamamoto T, Goldstein JL, Brown MS. Increased mRNA for low density lipoprotein in livers of rabbits treated with 17 alpha-ethinyl estradiol. Proc Natl Acad Sci U S A 1986;83: 792-6. Israelsson B, Brattstrom LE, Hultberg BL. Homocysteine and myocardial infarction. Atherosclerosis 1988;71:227-33. Brattstrom LE, Hardebo JE, Hultberg BL. Moderate homocysteinemia—a possible risk factor for arteriosclerotic cerebrovascular disease. Stroke 1984;15:1012-6. Malinow MR, Kang SS, Taylor LM, Wong PWK, Coull B, Inahara T, et al. Prevalence of hyperhomocyst(e)inemia in patients with peripheral arterial occlusive disease. Circulation 1989;79:1180-8. Stampfer MJ, Malinov MR, Willet WC, Newcomer LM, Upson B, Ullmann D, et al. A prospective study of plasma homocyst(e)ine and risk of myocardial infarction in US physicians. JAMA 1992;268:877-81. Andersson A, Brattstrom L, Israelson B, Isaksson A, Hamfelt A, Hultberg B. Plasma homocysteine before and after methionine loading with regard to age, gender, and menopausal status. Eur J Clin Invest 1992;22:79-87. Van Der Mooren MJ, Wouters MGAJ, Blom HJ, Schellekens LA, Eskes TKAB, Rolland R. Hormone replacement therapy may reduce high serum homocysteine in postmenopausal women. Eur J Clin Invest 1994;24:733-6. Reed T, Malinow MR, Christian JC, Upson B. Estimates of heritability of plasma homocyst(e)ine levels in aging adult male twins. Clin Genet 1991;39:425-8. Selhub J, Jacques PF, Wilson PW, Rush D, Rosenberg IH. Vitamin status and intake as primary determinants of homocysteinemia in an elderly population. JAMA 1993;270:2693-8. Homocysteine Lowering Trialists’ Collaboration. Lowering blood homocysteine with folic acid based supplements: metaanalysis of randomised trials. BMJ 1998;316:894-8. Brouwer IA, Van Dusseldorp M, Thomas CMG, Duran M, Hautvast JGAJ, Eskes TKAB, et al. Low-dose folic acid supplementation decreases plasma homocysteine concentrations: a randomized trial. Am J Clin Nutr 1999;69:99-104. Mijatovic V, Kenemans P, Netelenbos JC, Jakobs C, PoppSnijders C, Peters-Muller ERA, et al. Postmenopausal oral 17betaestradiol continuously combined with dydrogesterone reduces fasting serum homocysteine levels. Fertil Steril 1998;69:876-82. Anker G, Lonning PE, Ueland PM, Refsum H, Lien EA. Plasma levels of the atherogenic amino acid homocysteine in postmenopausal women with breast cancer treated with tamoxifen. Int J Cancer 1995;60:365-8. De Leo V, la Marca A, Morgante G, Ciani F, Zammarchi E, Setacci C. Low-dose folic acid supplementation reduces plasma levels of the cardiovascular risk factor homocysteine in postmenopausal women. Am J Obstet Gynecol 2000;183:945-7. Barrett-Connor E, Wenger NK, Grady D, Mosca L, Collins P, Kornitzer M, et al. Coronary heart disease in women, randomized clinical trials, HERS and RUTH. Maturitas 1998;31:1-7.
Key words: Raloxifene, older women, lipids, homocysteine
Estrogen replacement therapy, with or without progesterone, is associated with a reduction in the risk for osteoporosis,1 cardiovascular disease,2 and overall mortality.3 However, there are undesirable effects associated with estrogen therapy that reduce patient compliance; they include resumption of menses, mastodynia, and a perceived increased risk for uterine and breast cancer.4, 5 SERMS, a novel class of selective estrogen receptor modulators, have potential as viable alternatives to estrogen in hormone replacement therapy. Raloxifene, a nonsteroid benzothiophene SERM, has beneficial estrogen From the Department of Obstetrics and Gynecology and the Department of Vascular Surgery, University of Siena. Received for publication April 24, 2000; revised June 6, 2000; accepted August 22, 2000. Reprint requests: Vincenzo De Leo, MD, Department of Obstetrics and Gynecology, University of Siena, Policlinico Le Scotte, Viale Bracci, 53100 Siena (SI), Italy. E-mail: [email protected]. Copyright © 2001 by Mosby, Inc. 0002-9378/2001 $35.00 + 0 6/1/111065 doi:10.1067/mob.2001.111065
350
agonist effects on bone5, 6 and cardiovascular risk factors7 and estrogen antagonist effects on the breast and uterus. Limited clinical data5-7 have shown a rapid and sustained decrease in total and low-density lipoprotein (LDL) cholesterol levels similar to that seen with hormone replacement therapy. Raloxifene has been shown to reduce plasma concentrations of homocysteine, an independent risk factor for atherosclerosis and thromboembolic disease.8, 9 Studies concerning homocysteine were conducted with relatively young populations of women (for reference 8, mean age, 54 years; for reference 9, range of 45-72 years with an average of 10 years past menopause). Raloxifene, however, does not affect hot flushes, a major immediate symptom of menopause. This drug may therefore be useful in older women to prevent osteoporosis and cardiovascular disease. The aim of the current clinical study was to evaluate the effects of raloxifene on plasma lipids and homocysteine in older women.
De Leo et al 351
Volume 184, Number 3 Am J Obstet Gynecol
Material and methods The subjects were 45 healthy postmenopausal women, aged 60 to 70 years. Postmenopausal status was confirmed by follicle-stimulating hormone levels of at least 40 IU/L and estradiol levels <40 pg/mL (147 pmol/L). Exclusion criteria were recent thromboembolism, history of breast carcinoma, renal dysfunction, use of lipid-lowering drugs, and use of sex steroids more recently than 1 year before the start of the study. Informed consent was obtained from all subjects. The women were randomly assigned (by a random number table with an assignment criterion of 4 subjects to treatment and 3 subjects to placebo) to therapy with raloxifene 60 mg/d or placebo for 1 year. Twenty-six women received raloxifene and 19 received placebo. All women took oral calcium carbonate (500 mg/d elemental calcium) throughout the study. Checkups were performed every 3 months. At baseline and after 3, 6, 9, and 12 months of treatment we measured homocysteine, total serum cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides. LDL cholesterol was calculated by the Friedewald formula (LDL cholesterol = Total cholesterol – HDL cholesterol – Triglycerides × 0.2). At baseline and after 6 and 12 months the double-layer thickness of the uterine endometrium was determined by transvaginal ultrasonography (Sonoline SL-2; Siemens, Milan, Italy) performed by the same physician (Antonio la Marca). Compliance was assessed by interview at the end of treatment. No patients dropped out of the study. For the assays 3 mL of whole blood was drawn into a Vacutainer blood-collecting tube containing ethylenediaminetetraacetic acid (EDTA), cooled on ice, and immediately centrifuged at 1000g for 5 minutes at 4°C. Total homocysteine was determined by high-performance liquid chromatography with fluorescence detection according to the method of Araki and Sako,10 using a Kontron 320 (Kontron Instruments, Milan, Italy) system. The fluorescence intensities were measured with a Kontron SFM 25 (Kontron Instruments) fluorescence spectrophotometer. Statistical analysis. The results were expressed as mean ± SD. Non–Gaussian-distributed variables were transformed logarithmically before analysis. For clarity, non– log-transformed data are presented in Table I and Figs 1 and 2. The results were analyzed by analysis of variance with the Mann-Whitney test and the Student t test. Statistical significance was taken at P < .05. Results The demographic details of the study population are shown in Table I. Subjects were 60 to 70 years old and were an average of 17.5 years past menopause. There were no significant differences in age, body mass index, lipid levels, and homocysteine levels between the treated and placebo groups. As shown in Fig 1, an effect on lipids was evident by 3 months with no significant additional
Table I. Demographic details of study population
Age (y) Body mass index (kg/m2) Follicle-stimulating hormone (IU/L) Estradiol (pg/mL) Total cholesterol (mg/dL) LDL cholesterol (mg/dL) HDL cholesterol (mg/dL) Triglycerides (mg/dL) Homocysteine (µmol/L)
Raloxifene (n = 26)
Placebo (n = 19)
66 ± 3 24 ± 4.4 58 ± 8 15 ± 4 225 ± 53 138 ± 29 65 ± 17 110 ± 23 11 ± 2.1
65 ± 4 23 ± 5.2 61 ± 9 15 ± 5 218 ± 46 135 ± 27 62 ± 16 105 ± 21 11.5 ± 2.3
modification at 12 months. Mean LDL cholesterol levels were lowered by 15%, and total cholesterol levels were lowered by 8.5%. No reduction in HDL cholesterol or triglycerides was observed. After 3 months of therapy the homocysteine level was significantly lower than at baseline (9.9 ± 1.6 vs 11 ± 2.1 µmol/L; P < .05). The greatest reduction with respect to baseline was reached after 6 months of therapy (–19.5% ± 3%; P < .05; Fig 2). The median baseline endometrial thickness ranged from 1.6 to 2.3 mm in each group. There was no difference in endometrial thickness between groups at any time during the study. Comment Raloxifene is a benzothiophene derivative with which relatively much experience has been gained. It has beneficial estrogen agonist effects on bone and cardiovascular risk factors, but estrogen antagonist effects on the endometrium. It does not improve hot flushes but could be used in older women; however, few such studies have as yet been conducted. The results of our study show that raloxifene at a dose of 60 mg/d reduces serum concentrations of LDL cholesterol and total cholesterol in healthy women, without modifying levels of HDL cholesterol and triglycerides. These results confirm previous reports. It is thought that raloxifene reduces LDL cholesterol levels by enhancing LDL clearance by induction of hepatic LDL receptors.11, 12 However, raloxifene does not appear to have full agonist activity against the target(s) that estrogen modulates the increase in HDL cholesterol. Homocysteine is an independent risk factor for premature vascular disorders, including coronary,13 cerebrovascular,14 and peripheral vascular15 disease. The results of a prospective study by US physicians16 suggest that moderate serum levels of homocysteine are associated with an increased risk of premature vascular disorders. When they were compared with control subjects who were matched for age and smoking habits, subjects who previously had a myocardial infarction had significantly higher basal plasma concentrations of homocysteine.
352 De Leo et al
February 2001 Am J Obstet Gynecol
A
B
C
D
Fig 1. Percent changes from baseline in LDL cholesterol (A), total cholesterol (B), HDL cholesterol (C), and triglycerides (D) after placebo (circles) or raloxifene (squares) treatment. Asterisk, P < .05.
Fig 2. Percent changes from baseline in homocysteine levels after placebo (circles) or raloxifene (squares) treatment. Asterisk, P < .05.
There are indications that plasma homocysteine is related to estrogen status. Premenopausal women have lower plasma homocysteine levels than men and postmenopausal women17 and plasma homocysteine decreases in menopausal women on a regimen of estrogen replacement therapy.18 Plasma homocysteine levels are partly genetically determined,19 but acquired states such as cobalamine and folate deficiencies and renal failure may increase them.
Folate (as methyltetrahydrofolate) is required for methylation of homocysteine to methionine catalyzed by methionine synthase with vitamin B12 as cofactor. Blood levels of homocysteine are inversely related to blood levels of folate, vitamin B12, and vitamin B6.20 Several randomized controlled trials have shown that dietary supplements of folic acid lowered homocysteine levels.21, 22 A significant reduction in basal homocysteine in healthy postmenopausal women has been reported after hormone replacement therapy.7, 18, 23 Tamoxifene, a firstgeneration SERM, has been reported to reduce plasma homocysteine levels, and there is evidence that long-term treatment of patients with breast cancer with tamoxifene is associated with reduced cardiovascular mortality.24 It has recently been demonstrated that raloxifene decreases fasting plasma levels of homocysteine in a doserelated manner. Plasma homocysteine levels were significantly decreased with raloxifene 150 mg/d but not with raloxifene 60 mg/d.8 Another study concluded that hormone replacement therapy and raloxifene (60 and 120 mg/d) lower serum homocysteine levels to a comparable extent in postmenopausal women.9 Our study shows that in older women 60 mg/d leads to a 19.5% ± 3% reduction in fasting homocysteine levels. In a recent study25 we showed that folic acid supplements reduced plasma levels of homocysteine in postmenopausal women and that women with the highest ini-
De Leo et al 353
Volume 184, Number 3 Am J Obstet Gynecol
tial levels of homocysteine showed the greatest reduction after therapy. It is probable that higher basal levels of homocysteine in the women of our study with respect to the study by Mijatovic et al8 could explain the statistically significant reduction in homocysteine levels after raloxifene therapy in our results. The favorable preclinical effects of raloxifene on the cardiovascular system include inhibition of atherogenesis in cholesterol-fed rabbits, lowering of total cholesterol in ovariectomized rats and inhibition of LDL oxidation in vitro, inhibition of intimal thickening in carotid arteries of injured rats, increased endothelial cell basal nitric oxide availability, increased human umbilical vein endothelial cell thrombomodulin, and inhibition of vascular smooth muscle cell migration (for review see reference 26). Taken together with the preclinical findings, the results of our study suggest that raloxifene may have a favorable effect on the incidence of cardiovascular disease in older women.
10.
11.
12.
13. 14.
15.
16.
17. REFERENCES
1. Kiel DP, Felson DT, Anderson JJ, Wilson PWF, Moskowitz MA. Hip fracture and the use of estrogen in postmenopausal women. N Engl J Med 1987;317:1169-74. 2. Grodstein F, Stampfer MJ, Manson JE, Colditz GA, Willett WC, Rosner B, et al. Postmenopausal estrogen and progestin use and the risk of cardiovascular disease. N Engl J Med 1996;335:453-61. 3. Grodstein F, Stampfer MJ, Colditz GA, Willet WC, Manson JE, Joffe M, et al. Postmenopausal hormone replacement therapy and mortality. N Engl J Med 1997;336:1769-75. 4. Hulley S, Grady D, Bush T, Furberg C, Herrington D, Riggs B, et al. Randomized trial of estrogen plus progestin for secondary prevention of coronary heart disease in postmenopausal women. Heart and Estrogen/Progestin Replacement Study (HERS) Research Group. JAMA 1998;280:605-13. 5. Delmas PD, Bjarnason NH, Mitlak BH, Ravoux A, Shah AS, Huster WJ, et al. The effect of raloxifene on bone mineral density, serum cholesterol, and uterine endometrium in postmenopausal women. N Engl J Med 1997;337:1641-7. 6. Walsh BW, Kuller LH, Wild RA, Paul S, Farmer M, Lawrence JB, et al. Effects of raloxifene on serum lipids and coagulation factors in healthy postmenopausal women. JAMA 1998;279: 1445-51. 7. Draper MW, Flowers DE, Huster WJ, Neild JA, Harper KD, Arnaud C. A controlled trial of raloxifene (LY139481) HCL: impact on bone turnover and serum lipid profile in healthy, postmenopausal women. J Bone Miner Res 1996;11:835-42. 8. Mijatovic V, Netelenbos C, van der Mooren MJ, de Valk-de ROO GW, Jakobs C, Kenemans P. Randomized, double-blind, placebocontrolled study of the effects of raloxifene and conjugated equine estrogen on plasma homocysteine levels in healthy postmenopausal women. Fertil Steril 1998;70:1085-9. 9. Walsh BW, Paul S, Wild RA, Dean RA, Tracy RP, Cox DA, et al. The effects of hormone replacement therapy and raloxifene on
18.
19.
20.
21.
22.
23.
24.
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