FOSAMAX PLUS D ALENDRONATE SODIUM and CHOLECALCIFEROL 70 mg; 5600 [iU]/1 Tablet, 4-count — NDC 78206-136-01 (Billing 78206-0136-01)

12 CLINICAL PHARMACOLOGY

12.1Mechanism of Action Alendronate Sodium Animal studies have indicated the following mode of action. At the cellular level, alendronate shows preferential localization to sites of bone resorption, specifically under osteoclasts. The osteoclasts adhere normally to the bone surface but lack the ruffled border that is indicative of active resorption.

Alendronate does not interfere with osteoclast recruitment or attachment, but it does inhibit osteoclast activity. Studies in mice on the localization of radioactive [ 3 H]alendronate in bone showed about 10-fold higher uptake on osteoclast surfaces than on osteoblast surfaces. Bones examined 6 and 49 days after [ 3 H]alendronate administration in rats and mice, respectively, showed that normal bone was formed on top of the alendronate, which was incorporated inside the matrix.

While incorporated in bone matrix, alendronate is not pharmacologically active. Thus, alendronate must be continuously administered to suppress osteoclasts on newly formed resorption surfaces. Histomorphometry in baboons and rats showed that alendronate treatment reduces bone turnover (i.e., the number of sites at which bone is remodeled).

In addition, bone formation exceeds bone resorption at these remodeling sites, leading to progressive gains in bone mass. Cholecalciferol Vitamin D 3 is produced in the skin by photochemical conversion of 7-dehydrocholesterol to previtamin D 3 by ultraviolet light. This is followed by non-enzymatic isomerization to vitamin D 3 .

In the absence of adequate sunlight exposure, vitamin D 3 is an essential dietary nutrient. Vitamin D 3 in skin and dietary vitamin D 3 (absorbed into chylomicrons) is converted to 25-hydroxyvitamin D 3 in the liver. Conversion to the active calcium-mobilizing hormone 1,25-dihydroxyvitamin D 3 (calcitriol) in the kidney is stimulated by both parathyroid hormone and hypophosphatemia.

The principal action of 1,25-dihydroxyvitamin D 3 is to increase intestinal absorption of both calcium and phosphate as well as regulate serum calcium, renal calcium and phosphate excretion, bone formation and bone resorption. Vitamin D is required for normal bone formation. Vitamin D insufficiency develops when both sunlight exposure and dietary intake are inadequate.

Insufficiency is associated with negative calcium balance, increased parathyroid hormone levels, bone loss, and increased risk of skeletal fracture. In severe cases, deficiency results in more severe hyperparathyroidism, hypophosphatemia, proximal muscle weakness, bone pain and osteomalacia.

12.2Pharmacodynamics Alendronate Sodium Alendronate is a bisphosphonate that binds to bone hydroxyapatite and specifically inhibits the activity of osteoclasts, the bone-resorbing cells. Alendronate reduces bone resorption with no direct effect on bone formation, although the latter process is ultimately reduced because bone resorption and formation are coupled during bone turnover. Daily oral doses of alendronate (5, 20, and 40 mg for six weeks) in postmenopausal women produced biochemical changes indicative of dose-dependent inhibition of bone resorption, including decreases in urinary calcium and urinary markers of bone collagen degradation (such as deoxypyridinoline and cross-linked N-telopeptides of type I collagen).

These biochemical changes tended to return toward baseline values as early as 3 weeks following the discontinuation of therapy with alendronate and did not differ from placebo after 7 months. Long-term treatment of osteoporosis with FOSAMAX 10 mg/day (for up to five years) reduced urinary excretion of markers of bone resorption, deoxypyridinoline and cross-linked N-telopeptides of type l collagen, by approximately 50% and 70%, respectively, to reach levels similar to those seen in healthy premenopausal women. The decrease in the rate of bone resorption indicated by these markers was evident as early as one month and at three to six months reached a plateau that was maintain… [Excerpted — this section continues on DailyMed.]

12.1Mechanism of Action Alendronate Sodium Animal studies have indicated the following mode of action. At the cellular level, alendronate shows preferential localization to sites of bone resorption, specifically under osteoclasts. The osteoclasts adhere normally to the bone surface but lack the ruffled border that is indicative of active resorption.

Alendronate does not interfere with osteoclast recruitment or attachment, but it does inhibit osteoclast activity. Studies in mice on the localization of radioactive [ 3 H]alendronate in bone showed about 10-fold higher uptake on osteoclast surfaces than on osteoblast surfaces. Bones examined 6 and 49 days after [ 3 H]alendronate administration in rats and mice, respectively, showed that normal bone was formed on top of the alendronate, which was incorporated inside the matrix.

While incorporated in bone matrix, alendronate is not pharmacologically active. Thus, alendronate must be continuously administered to suppress osteoclasts on newly formed resorption surfaces. Histomorphometry in baboons and rats showed that alendronate treatment reduces bone turnover (i.e., the number of sites at which bone is remodeled).

In addition, bone formation exceeds bone resorption at these remodeling sites, leading to progressive gains in bone mass. Cholecalciferol Vitamin D 3 is produced in the skin by photochemical conversion of 7-dehydrocholesterol to previtamin D 3 by ultraviolet light. This is followed by non-enzymatic isomerization to vitamin D 3 .

In the absence of adequate sunlight exposure, vitamin D 3 is an essential dietary nutrient. Vitamin D 3 in skin and dietary vitamin D 3 (absorbed into chylomicrons) is converted to 25-hydroxyvitamin D 3 in the liver. Conversion to the active calcium-mobilizing hormone 1,25-dihydroxyvitamin D 3 (calcitriol) in the kidney is stimulated by both parathyroid hormone and hypophosphatemia.

The principal action of 1,25-dihydroxyvitamin D 3 is to increase intestinal absorption of both calcium and phosphate as well as regulate serum calcium, renal calcium and phosphate excretion, bone formation and bone resorption. Vitamin D is required for normal bone formation. Vitamin D insufficiency develops when both sunlight exposure and dietary intake are inadequate.

Insufficiency is associated with negative calcium balance, increased parathyroid hormone levels, bone loss, and increased risk of skeletal fracture. In severe cases, deficiency results in more severe hyperparathyroidism, hypophosphatemia, proximal muscle weakness, bone pain and osteomalacia.

12.3Pharmacokinetics Absorption Alendronate Sodium Relative to an intravenous reference dose, the mean oral bioavailability of alendronate in women was 0.64% for doses ranging from 5 to 70 mg when administered after an overnight fast and two hours before a standardized breakfast. Oral bioavailability of the 10-mg tablet in men (0.59%) was similar to that in women when administered after an overnight fast and 2 hours before breakfast. In a study, the alendronate in the FOSAMAX PLUS D (70 mg/2800 international units) tablet and the FOSAMAX (alendronate sodium) 70-mg tablet were found to be equally bioavailable.

In a separate study, the alendronate in the FOSAMAX PLUS D (70 mg/5600 international units) tablet was found to be equally bioavailable to the alendronate in the FOSAMAX (alendronate sodium) 70-mg tablet. A study examining the effect of timing of a meal on the bioavailability of alendronate was performed in 49 postmenopausal women. Bioavailability was decreased (by approximately 40%) when 10 mg alendronate was administered either 0.5 or 1 hour before a standardized breakfast, when compared to dosing 2 hours before eating.

In studies of treatment and prevention of osteoporosis, alendronate was effective when administered at least 30 minutes before breakfast. Bioavailability was negligible whether alendronate was administered with or up to two hours after a standardized breakfast. Concomitant administration of alendronate with coffee or orange juice reduced bioavailability by approximately 60%.

Cholecalciferol Following administration of FOSAMAX PLUS D (70 mg/2800 international units) after an overnight fast and two hours before a standard meal, the baseline adjusted mean area under the serum-concentration-time curve (AUC 0-120 hrs ) for vitamin D 3 was 120.7 ng-hr/mL. The baseline adjusted mean maximal serum concentration (C max ) of vitamin D 3 was 4.0 ng/mL, and the baseline adjusted mean time to maximal serum concentration (T max ) was 10.6 hrs. The bioavailability of the 2800 international units vitamin D 3 in FOSAMAX PLUS D is similar to 2800 international units vitamin D 3 administered alone.

In a separate study, the baseline adjusted mean AUC 0-80 hrs and baseline adjusted mean C max for vitamin D 3 were 355.6 ng-hr/mL and 10.8 ng/mL, respectively. The baseline adjusted mean T max was 9.2 hrs. The bioavailability of the 5600 international units vitamin D 3 in the FOSAMAX PLUS D is similar to 5600 international units vitamin D 3 administered as two 2800 international units vitamin D 3 tablets.

Distribution Alendronate Sodium Preclinical studies (in male rats) show that alendronate transiently distributes to soft tissues following 1 mg/kg intravenous administration but is then rapidly redistributed to bone or excreted in the urine. The mean steady-state volume of distribution, exclusive of bone, is at least 28 L in humans. Concentrations of drug in plasma following therapeutic oral doses are too low (less than 5 ng/mL) for analytical detection.

Protein binding in human plasma is approximately 78%. Cholecalciferol Following absorption, vitamin D 3 enters the blood as part of chylomicrons. Vitamin D 3 is rapidly distributed mostly to the liver where it undergoes metabolism to 25-hydroxyvitamin D 3 , the major storage form.

Lesser amounts are distributed to adipose tissue and stored as vitamin D 3 at these sites for later release into the circulation. Circulating vitamin D 3 is bound to vitamin D-binding protein. Metabolism Alendronate Sodium There is no evidence that alendronate is metabolized in animals or humans.

Cholecalciferol Vitamin D 3 is rapidly metabolized by hydroxylation in the liver to 25-hydroxyvitamin D 3 , and subsequently metabolized in the kidney to 1,25-dihydroxyvitamin D 3 , which represents the biologically active form. Further hydroxylation occurs prior to elimination. A small percentage of vitamin D 3 undergoes glucuronidation prior to elimination.

Excretion Alendronate Sodium Following a single i… [Excerpted — this section continues on DailyMed.]

12.2Pharmacodynamics Alendronate Sodium Alendronate is a bisphosphonate that binds to bone hydroxyapatite and specifically inhibits the activity of osteoclasts, the bone-resorbing cells. Alendronate reduces bone resorption with no direct effect on bone formation, although the latter process is ultimately reduced because bone resorption and formation are coupled during bone turnover. Daily oral doses of alendronate (5, 20, and 40 mg for six weeks) in postmenopausal women produced biochemical changes indicative of dose-dependent inhibition of bone resorption, including decreases in urinary calcium and urinary markers of bone collagen degradation (such as deoxypyridinoline and cross-linked N-telopeptides of type I collagen).

These biochemical changes tended to return toward baseline values as early as 3 weeks following the discontinuation of therapy with alendronate and did not differ from placebo after 7 months. Long-term treatment of osteoporosis with FOSAMAX 10 mg/day (for up to five years) reduced urinary excretion of markers of bone resorption, deoxypyridinoline and cross-linked N-telopeptides of type l collagen, by approximately 50% and 70%, respectively, to reach levels similar to those seen in healthy premenopausal women. The decrease in the rate of bone resorption indicated by these markers was evident as early as one month and at three to six months reached a plateau that was maintained for the entire duration of treatment with FOSAMAX.

In osteoporosis treatment studies FOSAMAX 10 mg/day decreased the markers of bone formation, osteocalcin and bone specific alkaline phosphatase by approximately 50%, and total serum alkaline phosphatase by approximately 25 to 30% to reach a plateau after 6 to 12 months. Similar reductions in the rate of bone turnover were observed in postmenopausal women during one-year studies with once weekly FOSAMAX 70 mg for the treatment of osteoporosis. These data indicate that the rate of bone turnover reached a new steady-state, despite the progressive increase in the total amount of alendronate deposited within bone.

As a result of inhibition of bone resorption, asymptomatic reductions in serum calcium and phosphate concentrations were also observed following treatment with FOSAMAX. In the long-term studies, reductions from baseline in serum calcium (approximately 2%) and phosphate (approximately 4 to 6%) were evident the first month after the initiation of FOSAMAX 10 mg. No further decreases in serum calcium were observed for the five-year duration of treatment; however, serum phosphate returned toward prestudy levels during years three through five.

In one-year studies with once weekly FOSAMAX 70 mg, similar reductions were observed at 6 and 12 months. The reduction in serum phosphate may reflect not only the positive bone mineral balance due to FOSAMAX but also a decrease in renal phosphate reabsorption. Osteoporosis in Men Treatment of men with osteoporosis with FOSAMAX 10 mg/day for two years reduced urinary excretion of cross-linked N-telopeptides of type I collagen by approximately 60% and bone-specific alkaline phosphatase by approximately 40%.

Similar reductions were observed in a one-year study in men with osteoporosis receiving once weekly FOSAMAX 70 mg. Cholecalciferol Vitamin D is required for normal bone formation. Vitamin D insufficiency is associated with negative calcium balance, leading to increased parathyroid hormone levels and worsening of bone loss associated with osteoporosis.

When taken without vitamin D, alendronate is also associated with a reduction in serum calcium concentrations and increased parathyroid hormone levels. In a 15-week trial, 717 postmenopausal women and men, mean age 67 years, with osteoporosis (lumbar spine bone mineral density [BMD] of at least 2.5 standard deviations below the premenopausal mean) were randomized to receive either weekly FOSAMAX PLUS D 70 mg/2800 international units vitamin D or weekly FOSAMAX 70 mg alone with no vitamin D supplemen… [Excerpted — this section continues on DailyMed.]

14 CLINICAL STUDIES

14.1Treatment of Osteoporosis in Postmenopausal Women FOSAMAX Daily The efficacy of FOSAMAX 10 mg daily was assessed in four clinical trials. Study 1, a three-year, multicenter, double-blind, placebo-controlled, US clinical study enrolled 478 patients with a BMD T-score at or below minus 2.5 with or without a prior vertebral fracture; Study 2, a three-year, multicenter, double-blind, placebo-controlled, Multinational clinical study enrolled 516 patients with a BMD T-score at or below minus 2.5 with or without a prior vertebral fracture; Study 3, the Three-Year Study of the Fracture Intervention Trial (FIT), a study which enrolled 2027 postmenopausal patients with at least one baseline vertebral fracture; and Study 4, the Four-Year Study of FIT, a study which enrolled 4432 postmenopausal patients with low bone mass but without a baseline vertebral fracture.

Effect on Fracture Incidence To assess the effects of FOSAMAX on the incidence of vertebral fractures (detected by digitized radiography; approximately one third of these were clinically symptomatic), the U.S. and Multinational studies were combined in an analysis that compared placebo to the pooled dosage groups of FOSAMAX (5 or 10 mg for three years or 20 mg for two years followed by 5 mg for one year). There was a statistically significant reduction in the proportion of patients treated with FOSAMAX experiencing one or more new vertebral fractures relative to those treated with placebo (3.2% vs.

6.2%; a 48% relative risk reduction). A reduction in the total number of new vertebral fractures (4.2 vs. 11.3 per 100 patients) was also observed.

In the pooled analysis, patients who received FOSAMAX had a loss in stature that was statistically significantly less than was observed in those who received placebo (-3.0 mm vs. -4.6 mm). The Fracture Intervention Trial (FIT) consisted of two studies in postmenopausal women: the Three-Year Study of patients who had at least one baseline radiographic vertebral fracture and the Four-Year Study of patients with low bone mass but without a baseline vertebral fracture. In both studies of FIT, 96% of randomized patients completed the studies (i.e., had a closeout visit at the scheduled end of the study); approximately 80% of patients were still taking study medication upon completion.

Fracture Intervention Trial: Three-Year Study (patients with at least one baseline radiographic vertebral fracture) This randomized, double-blind, placebo-controlled, 2027-patient study (FOSAMAX, n=1022; placebo, n=1005) demonstrated that treatment with FOSAMAX resulted in statistically significant reductions in fracture incidence at three years as shown in Table 6. Table 6: Effect of FOSAMAX on Fracture Incidence in the Three-Year Study of FIT (patients with vertebral fracture at baseline) Percent of Patients FOSAMAX (n=1022) Placebo (n=1005) Absolute Reduction in Fracture Incidence Relative Reduction in Fracture Risk % Patients with: Vertebral fractures (diagnosed by X-ray) Number evaluable for vertebral fractures: FOSAMAX, n=984; placebo, n=966 ≥1 new vertebral fracture 7.9 15.0 7.1 47 p<0.001 ≥2 new vertebral fractures 0.5 4.9 4.4 90 Clinical (symptomatic) fractures Any clinical (symptomatic) fracture 13.8 18.1 4.3 26 p=0.007 ≥1 clinical (symptomatic) vertebral fracture 2.3 5.0 2.7 54 p<0.01 Hip fracture 1.1 2.2 1.1 51 p<0.05 Wrist (forearm) fracture 2.2 4.1 1.9 48 Furthermore, in this population of patients with baseline vertebral fracture, treatment with FOSAMAX significantly reduced the incidence of hospitalizations (25.0% vs.

30.7%). In the Three-Year Study of FIT, fractures of the hip occurred in 22 (2.2%) of 1005 patients on placebo and 11 (1.1%) of 1022 patients on FOSAMAX, p=0.047. Figure 1 displays the cumulative incidence of hip fractures in this study.

Figure 1: Cumulative Incidence of Hip Fractures in the Three-Year Study of FIT (patients with radiographic vertebral fracture at baseline) Fracture Intervention Trial: Four-Ye… [Excerpted — this section continues on DailyMed.]

13 NONCLINICAL TOXICOLOGY

13.1Carcinogenesis, Mutagenesis, Impairment of Fertility The following data are based on findings for the individual components of FOSAMAX PLUS D. Alendronate Sodium Harderian gland (a retro-orbital gland not present in humans) adenomas were increased in high-dose female mice (p=0.003) in a 92-week oral carcinogenicity study at doses of alendronate of 1, 3, and 10 mg/kg/day (males) or 1, 2, and 5 mg/kg/day (females). These doses are equivalent to 0.5 to 4 times the highest recommended clinical daily dose of 10 mg based on surface area, mg/m 2 .

The relevance of this finding to humans is unknown. Parafollicular cell (thyroid) adenomas were increased in high-dose male rats (p=0.003) in a 2-year oral carcinogenicity study at doses of 1 and 3.75 mg/kg body weight. These doses are equivalent to 1 and 4 times the 10-mg clinical daily dose based on surface area, mg/m 2 .

The relevance of this finding to humans is unknown. Alendronate was not genotoxic in the in vitro microbial mutagenesis assay with and without metabolic activation, in an in vitro mammalian cell mutagenesis assay, in an in vitro alkaline elution assay in rat hepatocytes, and in an in vivo chromosomal aberration assay in mice. In an in vitro chromosomal aberration assay in Chinese hamster ovary cells, however, alendronate gave equivocal results.

Alendronate had no effect on fertility (male or female) in rats at oral doses up to 5 mg/kg/day (4 times the 10-mg clinical daily dose based on surface area, mg/m 2 ). Cholecalciferol The carcinogenic potential of cholecalciferol (vitamin D 3 ) has not been studied in rodents. Calcitriol, the hormonal metabolite of cholecalciferol, was not genotoxic in the Ames microbial mutagenesis assay with or without metabolic activation, and in an in vivo micronucleus assay in mice.

Ergocalciferol (vitamin D 2 ) at high doses (150,000 to 200,000 international units/kg/day) administered prior to mating resulted in altered estrous cycle and inhibition of pregnancy in rats. The potential effect of cholecalciferol on male fertility is unknown in rats.

13.2Animal Toxicology and/or Pharmacology The relative inhibitory activities on bone resorption and mineralization of alendronate and etidronate were compared in the Schenk assay, which is based on histological examination of the epiphyses of growing rats. In this assay, the lowest dose of alendronate that interfered with bone mineralization (leading to osteomalacia) was 6000-fold the antiresorptive dose. The corresponding ratio for etidronate was one to one.

These data suggest that alendronate administered in therapeutic doses is highly unlikely to induce osteomalacia.