Raloxifene Hydrochloride 60 mg Tablet, Film Coated, 1,000-count — NDC 65162-057-11 (Billing 65162-0057-11)

12 CLINICAL PHARMACOLOGY

12.1Mechanism of Action Raloxifene is an estrogen agonist/antagonist, commonly referred to as a selective estrogen receptor modulator (SERM). The biological actions of raloxifene are largely mediated through binding to estrogen receptors. This binding results in activation of estrogenic pathways in some tissues (agonism) and blockade of estrogenic pathways in others (antagonism).

The agonistic or antagonistic action of raloxifene depends on the extent of recruitment of coactivators and corepressors to estrogen receptor (ER) target gene promoters. Raloxifene appears to act as an estrogen agonist in bone. It decreases bone resorption and bone turnover, increases bone mineral density (BMD) and decreases fracture incidence.

Preclinical data demonstrate that raloxifene is an estrogen antagonist in uterine and breast tissues. These results are consistent with findings in clinical trials, which suggest that raloxifene hydrochloride lacks estrogen-like effects on the uterus and breast tissue.

12.2Pharmacodynamics Decreases in estrogen levels after oophorectomy or menopause lead to increases in bone resorption and accelerated bone loss. Bone is initially lost rapidly because the compensatory increase in bone formation is inadequate to offset resorptive losses. In addition to loss of estrogen, this imbalance between resorption and formation may be due to age-related impairment of osteoblasts or their precursors.

In some women, these changes will eventually lead to decreased bone mass, osteoporosis, and increased risk for fractures, particularly of the spine, hip, and wrist. Vertebral fractures are the most common type of osteoporotic fracture in postmenopausal women. In both the osteoporosis treatment and prevention trials, raloxifene hydrochloride therapy resulted in consistent, statistically significant suppression of bone resorption and bone formation, as reflected by changes in serum and urine markers of bone turnover (e.g., 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. In a 31-week, open-label, radiocalcium kinetics study, 33 early postmenopausal women were randomized to treatment with once-daily raloxifene hydrochloride 60 mg, cyclic estrogen/progestin (0.625 mg conjugated estrogens daily with 5 mg medroxyprogesterone acetate daily for the first 2 weeks of each month [hormone therapy]), or no treatment. Treatment with either raloxifene hydrochloride or hormone therapy was associated with reduced bone resorption and a positive shift in calcium balance (-82 mg Ca/day and +60 mg Ca/day, respectively, for raloxifene hydrochloride and -162 mg Ca/day and +91 mg Ca/day, respectively, for hormone therapy).

There were small decreases in serum total calcium, inorganic phosphate, total protein, and albumin, which were generally of lesser magnitude than decreases observed during estrogen or hormone therapy. Platelet count was also decreased slightly and was not different from estrogen therapy.

12.3Pharmacokinetics The disposition of raloxifene has been evaluated in more than 3,000 postmenopausal women in selected raloxifene osteoporosis treatment and prevention clinical trials, using a population approach. Pharmacokinetic data also were obtained in conventional pharmacology studies in 292 postmenopausal women. Raloxifene exhibits high within-subject variability (approximately 30% coefficient of variation) of most pharmacokinetic parameters.

Table 3 summarizes the pharmacokinetic parameters of raloxifene. Absorption — Raloxifene is absorbed rapidly after oral administration. Approximately 60% of an oral dose is absorbed, but presystemic glucuronide conjugation is extensive.

Absolute bioavailability of raloxifene is 2%. The time to reach average maximum plasma concentration and bioavailability are functions of systemic interconversion and enteroh… [Excerpted — this section continues on DailyMed.]

12.1Mechanism of Action Raloxifene is an estrogen agonist/antagonist, commonly referred to as a selective estrogen receptor modulator (SERM). The biological actions of raloxifene are largely mediated through binding to estrogen receptors. This binding results in activation of estrogenic pathways in some tissues (agonism) and blockade of estrogenic pathways in others (antagonism).

The agonistic or antagonistic action of raloxifene depends on the extent of recruitment of coactivators and corepressors to estrogen receptor (ER) target gene promoters. Raloxifene appears to act as an estrogen agonist in bone. It decreases bone resorption and bone turnover, increases bone mineral density (BMD) and decreases fracture incidence.

Preclinical data demonstrate that raloxifene is an estrogen antagonist in uterine and breast tissues. These results are consistent with findings in clinical trials, which suggest that raloxifene hydrochloride lacks estrogen-like effects on the uterus and breast tissue.

12.3Pharmacokinetics The disposition of raloxifene has been evaluated in more than 3,000 postmenopausal women in selected raloxifene osteoporosis treatment and prevention clinical trials, using a population approach. Pharmacokinetic data also were obtained in conventional pharmacology studies in 292 postmenopausal women. Raloxifene exhibits high within-subject variability (approximately 30% coefficient of variation) of most pharmacokinetic parameters.

Table 3 summarizes the pharmacokinetic parameters of raloxifene. Absorption — Raloxifene is absorbed rapidly after oral administration. Approximately 60% of an oral dose is absorbed, but presystemic glucuronide conjugation is extensive.

Absolute bioavailability of raloxifene is 2%. The time to reach average maximum plasma concentration and bioavailability are functions of systemic interconversion and enterohepatic cycling of raloxifene and its glucuronide metabolites. Administration of raloxifene hydrochloride with a standardized, high-fat meal increases the absorption of raloxifene (C max 28% and AUC 16%), but does not lead to clinically meaningful changes in systemic exposure.

Raloxifene hydrochloride can be administered without regard to meals. Distribution — Following oral administration of single doses ranging from 30 mg to 150 mg of raloxifene hydrochloride, the apparent volume of distribution is 2,348 L/kg and is not dose dependent. Raloxifene and the monoglucuronide conjugates are highly (95%) bound to plasma proteins.

Raloxifene binds to both albumin and α1-acid glycoprotein, but not to sex-steroid binding globulin. Metabolism — Biotransformation and disposition of raloxifene in humans have been determined following oral administration of 14 C-labeled raloxifene. Raloxifene undergoes extensive first-pass metabolism to the glucuronide conjugates: raloxifene-4′-glucuronide, raloxifene-6-glucuronide and raloxifene-6, 4′-diglucuronide.

No other metabolites have been detected, providing strong evidence that raloxifene is not metabolized by cytochrome P450 pathways. Unconjugated raloxifene comprises less than 1% of the total radiolabeled material in plasma. The terminal log-linear portions of the plasma concentration curves for raloxifene and the glucuronides are generally parallel.

This is consistent with interconversion of raloxifene and the glucuronide metabolites. Following intravenous administration, raloxifene is cleared at a rate approximating hepatic blood flow. Apparent oral clearance is

44.1L/kg•hr. Raloxifene and its glucuronide conjugates are interconverted by reversible systemic metabolism and enterohepatic cycling, thereby prolonging its plasma elimination half-life to 27.7 hours after oral dosing. Results from single oral doses of raloxifene predict multiple-dose pharmacokinetics.

Following chronic dosing, clearance ranges from 40 to 60 L/kg•hr. Increasing doses of raloxifene hydrochloride (ranging from 30 mg to 150 mg) result in slightly less than a proportional increase in the area under the plasma time concentration curve (AUC). Excretion — Raloxifene is primarily excreted in feces, and less than 0.2% is excreted unchanged in urine.

Less than 6% of the raloxifene dose is eliminated in urine as glucuronide conjugates. Table 3: Summary of Raloxifene Pharmacokinetic Parameters in the Healthy Postmenopausal Woman C max a,b (ng/mL)/ (mg/kg) t 1/2 (hr) a AUC 0-∞ a,b (ng•hr/mL)/ (mg/kg) CL/F a (L/kg•hr) V/F a (L/kg) Single Dose Mean 0.50 27.7 27.2 44.1 2348 CV a (%) 52 10.7 to 273 c 44 46 52 Multiple Dose Mean 1.36 32.5 24.2 47.4 2853 CV a (%) 37 15.8 to 86.6 c 36 41 56 a Abbreviations: C max = maximum plasma concentration, t 1/2 = half-life, AUC = area under the curve, CL = clearance, V = volume of distribution, F = bioavailability, CV = coefficient of variation. b Data normalized for dose in mg and body weight in kg. c Range of observed half-life.

Special Populations Pediatric — The pharmacokinetics of raloxifene has not been evaluated in a pediatric population… [Excerpted — this section continues on DailyMed.]

12.2Pharmacodynamics Decreases in estrogen levels after oophorectomy or menopause lead to increases in bone resorption and accelerated bone loss. Bone is initially lost rapidly because the compensatory increase in bone formation is inadequate to offset resorptive losses. In addition to loss of estrogen, this imbalance between resorption and formation may be due to age-related impairment of osteoblasts or their precursors.

In some women, these changes will eventually lead to decreased bone mass, osteoporosis, and increased risk for fractures, particularly of the spine, hip, and wrist. Vertebral fractures are the most common type of osteoporotic fracture in postmenopausal women. In both the osteoporosis treatment and prevention trials, raloxifene hydrochloride therapy resulted in consistent, statistically significant suppression of bone resorption and bone formation, as reflected by changes in serum and urine markers of bone turnover (e.g., 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. In a 31-week, open-label, radiocalcium kinetics study, 33 early postmenopausal women were randomized to treatment with once-daily raloxifene hydrochloride 60 mg, cyclic estrogen/progestin (0.625 mg conjugated estrogens daily with 5 mg medroxyprogesterone acetate daily for the first 2 weeks of each month [hormone therapy]), or no treatment. Treatment with either raloxifene hydrochloride or hormone therapy was associated with reduced bone resorption and a positive shift in calcium balance (-82 mg Ca/day and +60 mg Ca/day, respectively, for raloxifene hydrochloride and -162 mg Ca/day and +91 mg Ca/day, respectively, for hormone therapy).

There were small decreases in serum total calcium, inorganic phosphate, total protein, and albumin, which were generally of lesser magnitude than decreases observed during estrogen or hormone therapy. Platelet count was also decreased slightly and was not different from estrogen therapy.

14 CLINICAL STUDIES

14.1Treatment of Postmenopausal Osteoporosis Effect on Fracture Incidence The effects of raloxifene hydrochloride 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 (MORE). All vertebral fractures were diagnosed radiographically; some of these fractures also were associated with symptoms (i.e. clinical fractures). The study population consisted of 7,705 postmenopausal women with osteoporosis as defined by: a) low BMD (vertebral or hip BMD 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. Effect on Bone Mineral Density Raloxifene hydrochloride, 60 mg administered once daily, increased spine and hip BMD by 2 to 3%. Raloxifene hydrochloride decreased the incidence of the first vertebral fracture from 4.3% for placebo to 1.9% for raloxifene hydrochloride (relative risk reduction = 55%) and subsequent vertebral fractures from 20.2% for placebo to 14.1% for raloxifene hydrochloride (relative risk reduction = 30%) ( see Table 4).

All women in the study received calcium (500 mg/day) and vitamin D (400 to 600 IU/day). Raloxifene hydrochloride reduced the incidence of vertebral fractures whether or not patients had a vertebral fracture upon study entry. The decrease in incidence of vertebral fracture was greater than could be accounted for by increase in BMD alone.

Table 4: Effect of Raloxifene Hydrochloride on Risk of Vertebral Fractures Number of Patients Absolute Risk Reduction (ARR) Relative Risk Reduction (95% CI) Raloxifene Hydrochloride Placebo Fractures diagnosed radiographically Patients with no baseline fracture a n=1401 n=1457 Number (%) of patients with ≥ 1 new vertebral fracture 27 (1.9%) 62 (4.3%) 2.4% 55% (29%, 71%) Patients with ≥ 1 baseline fracture a n=858 n=835 Number (%) of patients with ≥ 1 new vertebral fracture 121 (14.1%) 169 (20.2%) 6.1% 30% (14%, 44%) Symptomatic vertebral fractures All randomized patients n=2557 n=2576 Number (%) of patients with ≥ 1 new clinical (painful) vertebral fracture 47 (1.8%) 81 (3.1%) 1.3% 41% (17%, 59%) a Includes all patients with baseline and at least one follow-up radiograph.

The mean percentage change in BMD from baseline for raloxifene hydrochloride was statistically significantly greater than for placebo at each skeletal site ( see Table 5). Table 5: Raloxifene Hydrochloride - (60 mg Once Daily) Related Increases in BMD a for the Osteoporosis Treatment Study Expressed as Mean Percentage Increase vs. Placebo b,c Time Site 12 Months % 24 Months % 36 Months % Lumbar Spine 2.0 2.6

2.6Femoral Neck 1.3 1.9

2.1 Ultradistal Radius ND d

2.2 ND d Distal Radius ND d

0.9 ND d Total Body ND d

1.1ND d a Note: all BMD increases were significant (p < 0.001). b Intent-to-treat analysis; last observation carried forward. c All patients received calcium and vitamin D. d 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 statistically significantly more frequent in the placebo group (3.7%) than in the raloxifene hydrochloride group (1.1%).

Bone Histology 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 raloxifene hydrochloride-treated patients, there were statistically 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… [Excerpted — this section continues on DailyMed.]

13 NONCLINICAL TOXICOLOGY

13.1Carcinogenesis, Mutagenesis, Impairment of Fertility Carcinogenesis — In a 21-month carcinogenicity study in mice, there was an increased incidence of ovarian tumors in female animals given 9 mg/kg to 242 mg/kg, which included benign and malignant tumors of granulosa/theca cell origin and benign tumors of epithelial cell origin. Systemic exposure (AUC) of raloxifene in this group was 0.3 to 34 times that in postmenopausal women administered a 60 mg dose. There was also an increased incidence of testicular interstitial cell tumors and prostatic adenomas and adenocarcinomas in male mice given 41 mg/kg or 210 mg/kg (4.7 or 24 times the AUC in humans) and prostatic leiomyoblastoma in male mice given 210 mg/kg.

In a 2-year carcinogenicity study in rats, an increased incidence in ovarian tumors of granulosa/theca cell origin was observed in female rats given 279 mg/kg (approximately 400 times the AUC in humans). The female rodents in these studies were treated during their reproductive lives when their ovaries were functional and responsive to hormonal stimulation. Mutagenesis — Raloxifene hydrochloride 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.

Impairment of Fertility — When male and female rats were given daily doses ≥ 5 mg/kg (≥ 0.8 times the human dose based on surface area, mg/m 2 ) prior to and during mating, no pregnancies occurred. In male rats, daily doses up to 100 mg/kg (16 times the human dose based on surface area, mg/m 2 ) for at least 2 weeks did not affect sperm production or quality or reproductive performance. In female rats, at doses of 0.1 to 10 mg/kg/day (0.02 to 1.6 times the human dose based on surface area, mg/m 2 ), raloxifene disrupted estrous cycles and inhibited ovulation.

These effects of raloxifene were reversible. In another study in rats in which raloxifene was given during the preimplantation period at doses ≥ 0.1 mg/kg (≥ 0.02 times the human dose based on surface area, mg/m 2 ), raloxifene delayed and disrupted embryo implantation, resulting in prolonged gestation and reduced litter size. The reproductive and developmental effects observed in animals are consistent with the estrogen receptor activity of raloxifene.

13.2Animal Toxicology and/or Pharmacology The skeletal effects of raloxifene treatment were assessed in ovariectomized rats and monkeys. In rats, raloxifene prevented increased bone resorption and bone loss after ovariectomy. There were positive effects of raloxifene on bone strength, but the effects varied with time.

Cynomolgus monkeys were treated with raloxifene or conjugated estrogens for 2 years. In terms of bone cycles, this is equivalent to approximately 6 years in humans. Raloxifene and estrogen suppressed bone turnover and increased BMD in the lumbar spine and in the central cancellous bone of the proximal tibia.

In this animal model, there was a positive correlation between vertebral compressive breaking force and BMD of the lumbar spine. Histologic examination of bone from rats and monkeys treated with raloxifene showed no evidence of woven bone, marrow fibrosis, or mineralization defects. These results are consistent with data from human studies of radiocalcium kinetics and markers of bone metabolism, and are consistent with the action of raloxifene hydrochloride as a skeletal antiresorptive agent.