Evista - Pharmaceutical Information, Clinical Trials, Detailed Pharmacology, Toxicology.
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Evista - Scientific Information

Manufacture: Eli Lilly and Company
Country: United States
Condition: Breast Cancer, Prevention, Osteoporosis, Prevention of Osteoporosis
Class: Hormones/antineoplastics, Selective estrogen receptor modulators
Form: Tablets
Ingredients: Raloxifene, hydrochloride, lactose

Pharmaceutical Information

Drug Substance

Proper name: raloxifene hydrochloride
Chemical name: methanone, [6-hydroxy-2-(4-hydroxyphenyl) benzo[b] thien-3-yl]-[4-[2-(1
piperidinyl)ethoxy]phenyl]-, hydrochloride
Molecular formula and molecular weight: C28H27NO4S•HCl
510.05
Structural formula:

Physicochemical properties:

Description: Raloxifene hydrochloride is an off-white to pale-yellow
solid that is very slightly soluble in water.
pH: 4.5 (25°C, saturated raloxifene hydrochloride solution in
water)
pKa: 8.44, 9.12, and 10.0 (extrapolated aqueous pKa’s)
Melting Point: 271-272°C

Clinical Trials

In postmenopausal women with osteoporosis, EVISTA (raloxifene hydrochloride) reduced the risk of fractures. EVISTA also increased BMD of the spine, hip and total body. Similarly, in postmenopausal women without osteoporosis, EVISTA preserved bone mass and increased BMD relative to calcium alone at 24 months. The effect on hip bone mass was similar to that for the spine.

Treatment of Osteoporosis

The effects of EVISTA on fracture incidence and BMD in postmenopausal women with osteoporosis were examined at 3 years in a large, randomized, placebo-controlled, double-blind multinational osteoporosis treatment trial. The study population consisted of 7705 postmenopausal women with osteoporosis as defined by: a) low BMD (vertebral or hip bone mineral density at least 2.5 standard deviations below the mean value for healthy young women) without baseline vertebral fractures, or b) one or more baseline vertebral fractures. Women enrolled in this study had a median age of 67 years (range 31 to 80) and a median time since menopause of 19 years. All women received calcium (500 mg/day) and vitamin D (400-600 IU/day).

EVISTA, 60 mg administered once daily, decreased the incidence of one or more vertebral fractures by as much as 55% (Table 1) and increased BMD compared to an active therapy of calcium plus vitamin D supplemented placebo. EVISTA reduced the incidence of vertebral fractures whether or not patients had experienced a previous fracture. The decrease in incidence of vertebral fracture was greater than could be accounted for by increase in BMD alone (Figure 1).

Table 1: Effect of EVISTA on Risk of Vertebral Fractures
Number of Patients Relative Risk
EVISTA Placebo (95% CI)
Patients with no baseline fracturea
   Number of patients with ≥1 new vertebral fracture
n=1401
27
n=1457
62

0.45
(0.29, 0.71)
Patients with ≥1 baseline fracturea
   Number of patients with ≥1 new vertebral fracture
n=858
121
n=835
169

0.70
(0.56, 0.86)
All randomized patients
   Number of patients with ≥1 new clinical (painful)
   vertebral fracture
n=2557
47
n=2576
81

0.59
(0.41, 0.83)

a   Includes all patients with baseline and at least one follow-up radiograph.

Figure 1:Changes in BMD do not fully account for vertebral fracture risk reduction. This figure shows the correlation between vertebral fracture risk and percent change in femoral neck BMD at 3 years based on a logistic regression analysis of the clinical trial data. For any given change in BMD from baseline, EVISTA-treated patients had a lower risk for vertebral fracture compared to placebo.

Retrospective analysis of the patients in the osteoporosis treatment study, demonstrates that there was a statistically significant reduction (p<0.001) in the risk of clinical (symptomatic) vertebral fracture after 12 months of treatment. At 12 months the risk of clinical vertebral fractures was decreased by 68% (95% CI, 0.13-0.79) in postmenopausal women taking EVISTA 60 mg per day.

The same osteoporosis treatment study was extended by 12 months to a 4th year during which, patients were permitted the use of concomitant medications, including bisphosphonates, calcitonins and fluorides. The statistically significant reduction in vertebral fractures and increase in BMD seen at 3 years continued into the 4th year extension of the osteoporosis treatment study. The sustained reduction in vertebral fractures is illustrated in Figure 2 below, a Kaplan-Meier analysis of time to first vertebral fracture over the 48 months of the study.

Figure 2: Time to Event for Vertebral Fractures Over 48 Months

Overall osteoporotic fracture risk was significantly reduced with EVISTA therapy. Over 4 years there was no difference seen in nonvertebral fracture incidence in women treated with raloxifene compared to placebo. At 3 years, the risk of individual nonvertebral fractures versus placebo decreased with increasing exposure to EVISTA.

At every time point, the mean percentage change in BMD from baseline for EVISTA was significantly greater than for placebo at each skeletal site measured (Table 2).

Table 2: EVISTA (60 mg Once Daily) Related Increases in BMD for the Osteoporosis Treatment Study Expressed as Mean Percentage Increase versus calciumand vitamin D-supplemented Placeboa
Site Time
12 Months
%
24 Months
%
36 Months
%
Lumbar Spine 2.0 2.6 2.6
Femoral Neck 1.3 1.9 2.1
Ultradistal Radius ND 2.2 ND
Distal Radius ND 0.9 ND
Total Body ND 1.1 ND

Note: all BMD increases were statistically significant (p<0.001)

a    Intent-to-treat analysis; last observation carried forward.

ND= not done (total body and radius BMD were measured only at 24 months)

Discontinuation from the study was required when excessive bone loss or multiple incident vertebral fractures occurred. Such discontinuation was significantly more frequent in the calcium- and vitamin D-supplemented placebo group (3.9%) than in the EVISTA group (1.1%).

Prevention of Osteoporosis

The effects of EVISTA on BMD in postmenopausal women were examined in three large randomized, placebo-controlled, double-blind osteoporosis prevention trials: (1) a North American trial enrolled 544 women; (2) a European trial, 601 women; and (3) an international trial, 619 women who had undergone hysterectomy. In these trials, all women received calcium supplementation (400 to 600 mg/day).

EVISTA, 60 mg administered once daily, produced significant increases in bone mass versus calcium supplementation alone, as reflected by dual-energy x-ray absorptiometric (DXA) measurements of hip, spine, and total body BMD. The increases in BMD were statistically significant at 12 months and were maintained at 24 months (Table 3). In contrast, the calciumsupplemented placebo groups lost approximately 1% of BMD over 24 months.

Table 3: EVISTA (60 mg Once Daily) Increases in BMD for the Three Osteoporosis Prevention Studies Expressed as Percentage Increase versus Calcium-Supplemented Placebo at 24 Months
Site Study
NA
%
EU
%
INTa
%
Total Hip 2.0 2.4 1.3
Femoral Neck 2.1 2.5 1.6
Trochanter 2.2 2.7 1.3
Intertrochanter 2.3 2.4 1.3
Lumbar Spine 2.0 2.4 1.8

Abbreviations: NA = North American, EU = European, INT = international.

a    All women in the study had previously undergone hysterectomy.

EVISTA also increased BMD compared with placebo in the total body by 1.3% to 2.0% and in Ward’s Triangle (hip) by 3.1% to 4.0%. In the international trial, conjugated equine estrogen 0.625 mg/day (ERT) was used as an active comparator. The mean increases in BMD at 24 months for estrogen compared with placebo were: lumbar spine, 5.4%; total hip, 2.9%. Thus, in postmenopausal women, EVISTA preserves bone mass and increases BMD significantly relative to calcium alone at 24 months. The effect on hip bone mass is similar to that for the spine.

Assessments of Bone Turnover

In a 31-week radiocalcium kinetics study, EVISTA was associated with reduced bone resorption and a positive shift in calcium balance (+60 mg Ca/day), due primarily to decreased urinary calcium losses. These findings were similar to those observed with hormone replacement therapy.

In both the osteoporosis treatment and prevention trials, EVISTA therapy resulted in consistent, statistically significant suppression of bone resorption, bone formation, and overall bone turnover, as reflected by changes in serum and urine markers of bone turnover (eg, bone-specific alkaline phosphatase, osteocalcin, and collagen breakdown products). The suppression of bone turnover markers was evident by 3 months and persisted throughout the 36-month and 24-month observation periods, respectively.

Bone Histomorphometry

In the treatment study, bone biopsies for qualitative and quantitative histomorphometry were obtained at baseline and after 2 years of treatment. There were 56 paired biopsies evaluable for all indices. In EVISTA-treated patients, there were significant decreases in bone formation rate per tissue volume, consistent with a reduction in bone turnover. Normal bone quality was maintained; specifically, there was no evidence of osteomalacia, marrow fibrosis, cellular toxicity or woven bone after 2 years of treatment.

The tissue- and cellular-level effects of raloxifene were assessed by quantitative measurements (bone histomorphometry) on animal bones and human iliac crest bone biopsies taken after administration of a fluorochrome substance to label areas of mineralizing bone. The effects of EVISTA on bone histomorphometry were determined by pre- and post-treatment biopsies in a 6-month study of postmenopausal women. Bone in EVISTA-treated women was histologically normal, showing no evidence of mineralization defects, woven bone, or marrow fibrosis. The patterns of change were consistent with reduced bone turnover, although most changes were not statistically significant. In another bone histomorphometry study, postmenopausal women were treated for 6 months with raloxifene HCl at a higher dose (150 mg/day). Bone was also histologically normal, with no woven bone, marrow fibrosis, or mineralization defects.

Effects on Lipid Metabolism

The effects of EVISTA on cardiovascular intermediate endpoints were evaluated in a 6-month study of 390 postmenopausal women. EVISTA was compared with continuous combined estrogen/progestin (0.625 mg conjugated equine estrogen plus 2.5 mg medroxyprogesterone acetate, [HRT]) and placebo (Table 4). EVISTA decreased serum total and LDL cholesterol without significant effects on serum total HDL cholesterol or triglycerides. EVISTA significantly increased HDL-2 cholesterol subfraction. In addition, EVISTA significantly decreased serum fibrinogen and lipoprotein (a).

Table 4: EVISTA and HRT Effects on Cardiovascular Intermediate Endpoints in a 6-Month Study -- Median Percentage Change from Baseline
Treatment Group
Endpoint PLACEBO
(N=98)
%
EVISTA
(N=95)
%
HRT
(N=96)
%
Total Cholesterol 0.9 -6.6 -4.4
LDL Cholesterol 1.0 -10.9 -12.7
HDL Cholesterol 0.9 0.7 10.6
HDL-2 Cholesterol 0.0 15.4 33.3
Fibrinogen -2.1 -12.2 -2.8
Lipoprotein (a) 3.3 -4.1 -16.3
Triglycerides -0.3 -4.1 20.0

Abbreviations: HRT = continuous combined estrogen/progestin (0.625 mg conjugated equine estrogen plus 2.5 mg medroxyprogesterone acetate).

Consistent with results from the 6-month study, in the osteoporosis treatment (36 months) and prevention (24 months) studies EVISTA significantly decreased serum total and LDL cholesterol, but did not increase HDL cholesterol or triglycerides. In the osteoporosis treatment study, significantly fewer EVISTA-treated patients required initiation of hypolipidemic therapy compared to placebo. EVISTA has no effect on clinical cardiovascular outcomes, in spite of the observed changes in lipid profile measurements (see WARNINGS AND PRECAUTIONS and CLINICAL TRIALS, Effects on the Cardiovascular System).

In a 12 patient, single-arm, open-label study in patients with a history of oral estrogen-induced marked hypertriglyceridemia (generally 5.6 to 39 mmol/L [500 to 3400 mg/dL]), 3 patients had increases of serum triglycerides to >11.3 mmol/L (1000 mg/dL) within 2 weeks after initiation of EVISTA therapy. In 2 of these 3 patients, serum triglyceride levels decreased while EVISTA was continued. Patients with this medical history should have serum triglycerides monitored when taking EVISTA.

Effects on the Uterus

In the osteoporosis treatment trial, endometrial thickness was evaluated annually in a subset of the study population (1781 patients) for 3 years. Endometrial thickness measurements in EVISTA-treated women were not different from baseline after 3 years of therapy. Placebotreated women had a 0.27 mm decrease from baseline in endometrial thickness over 3 years. There was no difference between EVISTA- and placebo-treated women in the incidences of endometrial carcinoma, vaginal bleeding or vaginal discharge.

In placebo-controlled osteoporosis prevention trials, endometrial thickness was evaluated every 6 months (for 24 months) by transvaginal ultrasonography (TVU), a non-invasive method of visualizing the uterus. A total of 2,978 TVU measurements were collected from 831 women in all dose groups. Raloxifene-treated women consistently had endometrial thickness measurements indistinguishable from placebo. Furthermore, there were no differences between the raloxifene and placebo groups with respect to the incidence of reported vaginal bleeding.

In a 6-month study comparing EVISTA to conjugated equine estrogens (0.625 mg/day [ERT]), endpoint endometrial biopsies demonstrated stimulatory effects of ERT which were not observed for EVISTA (Table 5). All samples from EVISTA-treated women showed nonproliferative endometrium.

Table 5: EVISTA and ERT Effects on Endometrial Histology After 6-Months of Therapy
Endpoint Biopsy Result Treatment Group
EVISTA
(n=10)
ERT
(n=8)
Nonproliferative Endometriuma 10 2
Proliferative Tissue 0 4
Simple Hyperplasia 0 2

Abbreviations: ERT = conjugated equine estrogens (0.625 mg/day).

a    The term nonproliferative endometrium includes endometrial atrophy, surface endometrium, and inadequatesample.

A 12-month study of uterine effects compared a higher dose of raloxifene HCl (150 mg/day) with HRT. At baseline, 43 raloxifene-treated women and 37 HRT-treated women had a nonproliferative endometrium. At study completion, endometrium in all of the raloxifene-treated women remained nonproliferative whereas 13 HRT-treated women had developed proliferative changes. Also, HRT significantly increased uterine volume; raloxifene did not increase uterine volume. Thus, no stimulatory effect of raloxifene on the endometrium was detected at more than twice the recommended dose.

EVISTA does not increase the risk of ovarian carcinoma.

Effects on the Breast

Across all placebo-controlled trials, EVISTA was indistinguishable from placebo with regard to frequency and severity of breast symptoms. EVISTA was associated with significantly fewer breast symptoms than reported by women receiving estrogens with or without added progestin (see ADVERSE REACTIONS).

In clinical trials with EVISTA involving 17,151 patients, at least 10,850 women were exposed to raloxifene for up to 58 months. All cases of breast cancer in women enrolled in clinical trials were reviewed without knowledge of treatment status (blinded) by an independent Adjudication Review Board. There was a statistically significant reduction in the frequency of newly diagnosed invasive breast cancers in raloxifene-treated women compared with placebo.

In a large 4-year randomized, placebo-controlled osteoporosis treatment trial, raloxifene compared to placebo reduced the incidence of invasive breast cancer by 72% (RR 0.28; 95% CI 0.17-0.46). The incidence rates were 5.3 per 1000 women-years for placebo, and 1.9 per 1000 women years for raloxifene. A portion of these patients participated in a 4-year placebocontrolled follow-up study. During the 4-year follow-up, raloxifene compared to placebo reduced the incidence of invasive breast cancer by 59% (HR 0.41; 95% CI 0.24-0.71). For the combined 8-year period, raloxifene reduced invasive breast cancer by 66% compared to placebo (HR 0.34; 95%CI 0.22-0.50). These observations are consistent with the preclinical pharmacologic profile of raloxifene (selective estrogen receptor modulator) and support the conclusion that EVISTA has no intrinsic estrogen agonist activity in mammary tissue. The longterm effectiveness of raloxifene in reducing the risk of breast cancer has not been fully established.

Effects on the Central Nervous System

EVISTA has not been associated with deterioration of cognitive function or a change in affect. In the Multiple Outcomes of Raloxifene Evaluation (MORE) trial, cognitive function was assessed as a secondary outcome in 7705 postmenopausal women with osteoporosis. Treatment with raloxifene at 60 mg/day or 120 mg/day for a 3 year period did not affect overall cognitive scores compared to placebo. In the same study, including a 1-year extension during which concomitant medications (bisphosphonates, calcitonins and fluorides) were permitted, neuropsychomotor tests showed no statistically significant differences between placebo and treatment groups for the 4 year period.

Effects on the Cardiovascular System

In placebo-controlled clinical trials ranging from 6 months to 5 years in duration, raloxifene has been shown to have no significant effect on C-reactive protein, and to significantly lower LDLcholesterol without changing HDL-cholesterol or triglyceride concentrations. In a large 4-year randomized, placebo-controlled osteoporosis treatment trial, there were no significant differences between raloxifene and placebo in the overall cohort with respect to combined coronary and cerebrovascular events.

The risk-benefit balance of EVISTA in postmenopausal women with a history of stroke or other significant stroke risk factors, such as transient ischemic attack or atrial fibrillation, should be considered when prescribing EVISTA. The Raloxifene Use for The Heart (RUTH) trial investigated the effects of EVISTA in postmenopausal women (average age = 67 years) with known heart disease or at high risk for a coronary event. The RUTH trial demonstrated an increase in mortality due to stroke for EVISTA compared to placebo. The incidence of stroke mortality was 1.5 per 1,000 women per year for placebo versus 2.2 per 1,000 women per year for EVISTA (p=0.0499). The incidence of stroke, myocardial infarction, hospitalized acute coronary syndrome, cardiovascular mortality, or overall mortality (all causes combined) was comparable for EVISTA and placebo. It can therefore be concluded that EVISTA has no effect on clinical cardiovascular outcomes, in spite of the observed changes in lipid profile measurements.

Detailed Pharmacology

Animal Pharmacology

Effects on Bone

The effects of raloxifene on bone mass, architecture, and quality have been evaluated in young adult or aged rats that were ovariectomized and then orally dosed for up to 12 months. Bone densitometry and histomorphometry showed that raloxifene has efficacy comparable to 17α-ethynyl estradiol or 17β-estradiol in preventing the loss of trabecular bone resulting from ovariectomy. Biomechanical analyses of bone quality showed that raloxifene is as efficacious as 17α-ethynyl estradiol in maintaining the mechanical integrity and strength of the lumbar vertebrae, femoral neck, and femoral diaphysis. Bone densitometry of lumbar vertebrae, distal femora, or proximal tibiae suggested that raloxifene HCl has maximal efficacy at a dose of 1 mg/kg, and half-maximal efficacy (ED50) at 0.3 mg/kg. In vivo potency differences between raloxifene and estrogen were observed, with 17α-ethynyl estradiol more potent than raloxifene. Serum and urinary biochemical markers of bone metabolism also showed that the effects of raloxifene parallel those of estrogen in OVX rats.

A similar pattern of activity was observed in OVX cynomolgus monkeys. Over a 2-year treatment period in OVX cynomolgus monkeys, raloxifene blunted the ovariectomy-induced elevation of circulating markers of bone metabolism and produced higher vertebral bone mineral density (BMD) when compared with OVX controls. While ovariectomy was not associated with consistently significant deficiencies in biomechanical strength of bone in this study, a significant correlation was observed between vertebral strength and vertebral BMD in control, estrogen-, and raloxifene-treated OVX monkeys. A significant correlation was also observed in OVX rats.

Furthermore, after the 2-year treatment period, biomechanical analysis of material properties of milled bone samples from monkeys revealed no adverse effects of raloxifene treatment on bone quality.

Histomorphometric evaluations in the OVX rat model showed that, similar to 17α-ethynyl estradiol, raloxifene blocks ovariectomy-stimulated bone resorption by inhibiting increases in osteoclast number, eroded perimeter, trabecular separation, and bone turnover. Raloxifene appears to have less suppressive effect on bone formation than estrogen under certain experimental conditions, although suppression of bone formation with raloxifene can be demonstrated in OVX rats and monkeys. Polarized light microscopy indicated that bone was of normal quality in the raloxifene-treated OVX monkeys following the 2-year treatment period, with no evidence of woven bone formation.

Collectively, these studies demonstrate that the raloxifene profile of effects on bone in rats and monkeys is very similar to that of estrogen.

Effects on the Cardiovascular System

The increased incidence of coronary heart disease in postmenopausal women is at least partially attributed to estrogen deficiency-induced changes in lipoprotein metabolism. Since the mechanisms by which estrogen lowers cholesterol in rats and humans are similar (i.e. induction of hepatic LDL receptors and enhanced clearance of LDL-C), the rat is a useful species in which to study the pharmacological effects of estrogen-like compounds on cholesterol homeostasis. Thus, the ability of estrogen and estrogen-like compounds to lower serum cholesterol in rats may be predictive of human effects.

In OVX rats, raloxifene produces a marked cholesterol-lowering effect similar to that of estrogen. After 5 weeks of treatment, raloxifene HCl significantly lowered serum cholesterol at oral doses as low as 0.1 mg/kg, with an ED50 of 0.2 mg/kg. This cholesterol-lowering activity was maintained during administration of raloxifene for up to 12 months. Dose-response curves for cholesterol lowering produced by 17α-ethynyl estradiol in the presence or absence of raloxifene indicated that cholesterol lowering by these two agents is not additive when one of them is present at a maximally effective dose. The cholesterol-lowering effect of raloxifene in rats appears to involve ER-mediated induction of hepatic LDL-receptors, leading to enhanced clearance of serum lipoproteins containing apolipoprotein B or apolipoprotein E. Additionally, a similar reduction in serum total cholesterol was observed in OVX monkeys during 24 months of treatment with raloxifene HCl using dosages which produced plasma concentrations of raloxifene similar to those in postmenopausal women receiving 60 mg/day of the drug.

In cholesterol-fed OVX rabbits, treatment with raloxifene led to a significant reduction in the accumulation of aortic cholesterol. The magnitude of this reduction was less than that observed in similar rabbits treated with 17β-estradiol. However, the plasma concentrations of raloxifene achieved in this study were low, relative to plasma concentrations observed in clinical trials. Similar to the situation with estrogen, the effect of raloxifene on aortic cholesterol accumulation could not be fully explained by alterations in serum lipids alone. However, no reduction of a high-cholesterol-diet-induced thickening of coronary intima in monkeys was observed after treatment with raloxifene.

In addition to its cholesterol-lowering activity, raloxifene also produces other cardiovascular effects in vitro or in animal models. These include inhibition of endothelial cell activation, inhibition of smooth-muscle cell migration, inhibition of LDL oxidation, and inhibition of intimal thickening in response to balloon injury in rats. In ovariectomized cholesterol fed rabbits with pre-induced atherosclerosis, raloxifene and estradiol treatment for a 39 week period significantly reduced the progression of atherosclerosis (p<0.01) compared to placebo.

Effects on the Uterus

In estrogen deficient animals (rats, rabbits, monkeys) raloxifene fails to produce estrogen-like stimulation of the uterus. While a small, non-dose-related elevation of uterine weight has been observed in ovariectomized rats (an effect attributed to water retention in the stromal compartment), no stimulation of the endometrium or other estrogen-sensitive uterine markers (i.e. eosinophilia) was observed.

Raloxifene fails to mimic estrogen’s stimulatory effect on the uterus; it is a potent and complete antagonist of estrogen induced uterine weight gain, eosinophilia, endometrial c-fos expression and glycogen synthesis. Raloxifene is unique among selective estrogen receptor modulators in this regard. The ability of raloxifene to function as a complete estrogen antagonist in the uterus is due to the lack of intrinsic activity at activating estrogen receptor mediated pathways in the uterus.

Effects on Mammary Tumours

Raloxifene completely antagonizes the proliferation of ERdependent mammary tumour cells, including the MCF-7 human cell line, with an inhibitory concentration for 50% inhibition (IC50) value of approximately 0.2 nM in vitro. The antiproliferative effect of raloxifene on estrogen-receptor-positive human breast cancer cell lines can be demonstrated in the presence of added estrogen, but raloxifene produces no proliferative effect when administered to these cells in the absence of estrogen (ie, lack of direct estrogen agonist activity). As might be expected, raloxifene has no antiproliferative activity against nonestrogen-dependent mammary carcinoma lines, such as the androgen-sensitive Shionogi mouse mammary carcinoma. In vivo, raloxifene effectively antagonizes the growth of established mammary tumours induced by carcinogens, (ie, dimethylbenzanthracene [DMBA]) or implanted as xenografts in athymic mice (ie, MCF-7). Raloxifene also prevents the development of mammary tumours induced by the chemical carcinogen nitrosomethylurea (NMU). In this prevention model, raloxifene (at 20 mg/kg orally) reduced tumour incidence by 57% and tumour burden by 82%.

In Vitro Pharmacology

Thrombomodulin

An in vitro study in human umbilical vein endothelial cells has demonstrated the effect of raloxifene on upregulating thrombomodulin, which results in an enhancing of the anticoagulant properties of unstimulated and IL-1-activated endothelial cells. Thrombomodulin is involved in the feedback mechanism of the coagulation cascade and studies have indicated that impaired expression of thrombomodulin may contribute to an increased risk for cardiovascular disease. The extent to which the observed effects of raloxifene on thrombomodulin activity occur in vivo is unknown.

Toxicology

Acute Toxicity

No mortality occurred in mice or rats administered single 5000-mg/kg oral doses of raloxifene HCl. An intraperitoneal dose of 2000 mg/kg given to rats produced 20% mortality. Clinical signs were limited to leg weakness, soft stools, and compound-colored feces in rats given raloxifene orally and to leg weakness, hypoactivity, and poor grooming in rats given the compound parenterally. No effects were seen in dogs or monkeys given a single oral dose of 300 mg/kg. Rhesus monkeys tolerated a single 300-mg/kg dose of raloxifene without developing any physical signs of toxicity.

Repeated-Dose Toxicity

B6C3F1 mice administered raloxifene HCl in the diet for 3 months at average daily doses up to approximately 120 mg/kg had decreases in body weight gain with no associated toxicologically important effects. The most notable treatment-related finding was the estrogen antagonist effect of decreased uterine weight. The 6-month and 1-year dietary studies in Fischer 344 rats at doses up to approximately 25 mg/kg produced similar findings.

In males, there were treatment-related decreases in food consumption and body weight gain. In female rats, decreased uterine weights and moderate elevations in serum alkaline phosphatase occurred at all doses. Moderate increases in adrenal weights were also seen in rats that received raloxifene, but these increases were not associated with any substantive histologic changes. Mineralization of the corticomedullary tubules of the kidneys occurred in both male and female rats of all dose groups. In a 6-month study in dogs at doses up to 30 mg/kg, the only treatmentrelated findings were decreased prostate weights in 2 of the 4 high-dose dogs, and aspermatogenesis and slight prostatic atrophy in 1 of those 2 dogs. The effects on the prostate are consistent with the pharmacologic activity of raloxifene. No effects were observed in female dogs. There were no proliferative changes and no ocular effects in the chronic studies in rats and dogs.

In subchronic studies conducted with CD-1 mice, Fischer 344 rats, and cynomolgus monkeys using raloxifene doses up to approximately 1700, 700, and 1000 mg/kg, respectively, results were similar to those of the subchronic and chronic studies described previously. The primary findings in rodents included reduced food consumption and reduced body weight; decreased uterine and pituitary weights; and uterine hypoplasia, vaginal mucoid metaplasia, and ovarian changes. However, in female mice, body weight was increased at raloxifene doses ≥184 mg/kg. The most important effects seen in monkeys treated for 1 month were decreased food consumption, various stool abnormalities in high-dose animals, and reduced thymus weights in males. At all doses, reduced uterine weights and ovarian cysts were observed. With the exception of the abnormal stools in monkeys given 1000 mg/kg, all of the changes produced by raloxifene treatment were attributable to its estrogen agonist/antagonist activity.

A 1-year toxicity study was conducted in cynomolgus monkeys to evaluate the effects of raloxifene HCl on intact females, OVX females, and juvenile males at daily raloxifene doses of 0, 15, 30, or 100 mg/kg. Increases (2- to 6-fold above control values) in serum alanine transaminase (ALT) were observed in all groups of raloxifene-treated OVX females, but only in the mid- and high-dose groups of intact females. Serum ALT values in males were unaffected. Other serum enzymes associated with impaired liver function were not similarly increased, and there were no significant morphologic hepatocellular changes in any treated animals. Because estrogen has been shown to induce elevations in serum transaminases in the absence of hepatocellular damage, the increased serum ALT values seen in this study were likely related to the estrogenic activity of raloxifene in the liver and were not an indicator of hepatocellular damage. Reduced uterine weight and generalized atrophy of the uterus occurred in intact females treated with raloxifene. In raloxifene-treated OVX females, the uteri were indistinguishable (in weight and morphology) from those of the OVX control group. Ovarian weights were significantly increased in the mid- and high-dose groups compared to the control. Ovaries in raloxifene-treated animals had developing follicles and/or corpora lutea, but no follicular cysts were seen in any treated animal. Pituitary weights were reduced in males at all dose levels and thymus weights were decreased in high-dose males, but neither of these changes was associated with any abnormal tissue morphology. There were no proliferative lesions in any tissues or organs and no ocular effects. All of the notable effects in this study were attributable to raloxifene's pharmacologic activity as a SERM, and were not considered to represent toxicologically important findings.

Carcinogenesis, Teratogenesis, Impairment of Fertility

In a 2-year carcinogenicity study in rats, an increased incidence in ovarian tumours of granulosa/theca cell origin was observed in females given 279 mg/kg. Systemic exposure (AUC) of raloxifene in this group was approximately 400 times that in postmenopausal women administered a 60 mg dose. In a 21-month carcinogenicity study in mice, there was an increased incidence of testicular interstitial cell tumours and prostatic adenomas and adenocarcinomas in males given 41 or 210 mg/kg, and prostatic leiomyoblastoma in males given 210 mg/kg. In female mice, an increased incidence of ovarian tumours in animals given 9 to 242 mg/kg (0.3 to 32 times the AUC in humans) included benign and malignant tumours of granulosa/theca cell origin and benign tumours of epithelial cell origin. The female rodents in these studies were treated during their reproductive lives when their ovaries were functional and highly responsive to hormonal stimulation. In contrast to the highly responsive ovaries in this rodent model, the human ovary after menopause is relatively unresponsive to reproductive hormonal stimulation.

In teratology studies, a no-observed-effect level of 0.1 mg/kg raloxifene HCl was established for fetal effects in CD rats, but fetal abnormalities were observed at the lowest doses tested in two strains of rabbits. The developmental deviation in rats was wavy ribs. In Dutch Belted rabbits at a dose of 10 mg/kg and in New Zealand white rabbits at doses ≥0.1 mg/kg, developmental toxicity was manifested as a low incidence of hydrocephaly (3 out of 56), and as a ventricular septal defect of the heart (3 out of 338), respectively.

When male and female rats were given daily doses >5 mg/kg prior to and during mating, no pregnancies occurred. In male rats, daily doses up to 100 mg/kg for at least 2 weeks did not affect sperm production or quality, or reproductive performance. At doses of 0.1 to 10 mg/kg/day in female rats, raloxifene disrupted estrous cycles during treatment, but did not delay fertile matings after treatment termination and marginally decreased litter size, increased gestation length, and altered the timing of events in neonatal development. When given during the preimplantation period, raloxifene delayed and disrupted embryo implantation resulting in prolonged gestation and reduced litter size, but development of offspring to weaning was not affected. The reproductive and developmental effects observed in animals are consistent with the estrogen receptor activity of raloxifene.

Mutagenesis

Raloxifene HCl was not genotoxic in any of the following test systems: the Ames test for bacterial mutagenesis with and without metabolic activation, the unscheduled DNA synthesis assay in rat hepatocytes, the mouse lymphoma assay for mammalian cell mutation, the chromosomal aberration assay in Chinese hamster ovary cells, the in vivo sister chromatid exchange assay in Chinese hamsters, and the in vivo micronucleus test in mice. Raloxifene HCl did not cause formation of DNA adducts in the liver of rats given an intraperitoneal dose of 20 mg/kg.