Ibandronate Sodium 3 mg/3mL Injection, Solution — NDC 55150-191-83 (Billing 55150-0191-83)

12 CLINICAL PHARMACOLOGY

12.1Mechanism of Action The action of ibandronate on bone is based on its affinity for hydroxyapatite, which is part of the mineral matrix of bone. Ibandronate inhibits osteoclast activity and reduces bone resorption and turnover. In postmenopausal women, it reduces the elevated rate of bone turnover, leading to, on average, a net gain in bone mass.

12.2Pharmacodynamics In studies of postmenopausal women, ibandronate sodium injection at doses of 0.5 mg to 3 mg produced biochemical changes indicative of inhibition of bone resorption, including decreases of biochemical markers of bone collagen degradation (cross-linked C-telopeptide of Type I collagen [CTX]). Changes in markers of bone formation (osteocalcin) were observed later than changes in resorption markers, as expected, due to the coupled nature of bone resorption and formation. Year 1 results from an efficacy and safety study comparing ibandronate sodium injection 3 mg every 3 months and ibandronate 2.5 mg daily oral tablet demonstrated that both dosing regimens significantly suppressed serum CTX levels at Months 3, 6, and 12.

The median pre-dose or trough serum CTX levels in the intent-to-treat population reached a nadir of 57% (ibandronate sodium injection) and 62% (ibandronate 2.5 mg tablets) below baseline values by Month 6, and remained stable at Month 12 of treatment.

12.3Pharmacokinetics Distribution Area under the serum ibandronate concentrations versus time curve increases in a dose proportional manner after administration of 2 mg to 6 mg by intravenous injection. After administration, ibandronate either rapidly binds to bone or is excreted into urine. In humans, the apparent terminal volume of distribution is at least 90 L, and the amount of dose removed from the circulation into the bone is estimated to be 40% to 50% of the circulating dose.

In one study, in vitro protein binding in human serum was approximately 86% over an ibandronate concentration range of 20 to 2,000 ng/mL (approximate range of maximum serum ibandronate concentrations upon intravenous bolus administration). Metabolism There is no evidence that ibandronate is metabolized in humans. Ibandronate does not inhibit human P450 1A2, 2A6, 2C9, 2C19, 2D6, 2E1, and 3A4 isozymes in vitro .

Ibandronate does not undergo hepatic metabolism and does not inhibit the hepatic cytochrome P450 system. Ibandronate is eliminated by renal excretion. Based on a rat study, the ibandronate secretory pathway does not appear to include known acidic or basic transport systems involved in the excretion of other drugs.

Elimination The portion of ibandronate that is not removed from the circulation via bone absorption is eliminated unchanged by the kidney (approximately 50% to 60% of the administered intravenous dose). The plasma elimination of ibandronate is multiphasic. Its renal clearance and distribution into bone accounts for a rapid and early decline in plasma concentrations, reaching 10% of C max within 3 or 8 hours after intravenous or oral administration, respectively.

This is followed by a slower clearance phase as ibandronate redistributes back into the blood from bone. The observed apparent terminal half-life for ibandronate is generally dependent on the dose studied and on assay sensitivity. The observed apparent terminal half-life for intravenous 2 and 4 mg ibandronate after 2 hours of infusion ranges from 4.6 to 15.3 hours and 5 to 25.5 hours, respectively.

Following intravenous administration, total clearance of ibandronate is low, with average values in the range 84 to 160 mL/min. Renal clearance (about 60 mL/min in healthy postmenopausal women) accounts for 50% to 60% of total clearance and is related to creatinine clearance. The difference between the apparent total and renal clearances likely reflects bone uptake of the drug.

Pharmacokinetics in Specific Populations Pediatrics The pharmacokinetics of ibandronate have not been studied in patients less than 18 years of age. Gen… [Excerpted — this section continues on DailyMed.]

12.1Mechanism of Action The action of ibandronate on bone is based on its affinity for hydroxyapatite, which is part of the mineral matrix of bone. Ibandronate inhibits osteoclast activity and reduces bone resorption and turnover. In postmenopausal women, it reduces the elevated rate of bone turnover, leading to, on average, a net gain in bone mass.

12.3Pharmacokinetics Distribution Area under the serum ibandronate concentrations versus time curve increases in a dose proportional manner after administration of 2 mg to 6 mg by intravenous injection. After administration, ibandronate either rapidly binds to bone or is excreted into urine. In humans, the apparent terminal volume of distribution is at least 90 L, and the amount of dose removed from the circulation into the bone is estimated to be 40% to 50% of the circulating dose.

In one study, in vitro protein binding in human serum was approximately 86% over an ibandronate concentration range of 20 to 2,000 ng/mL (approximate range of maximum serum ibandronate concentrations upon intravenous bolus administration). Metabolism There is no evidence that ibandronate is metabolized in humans. Ibandronate does not inhibit human P450 1A2, 2A6, 2C9, 2C19, 2D6, 2E1, and 3A4 isozymes in vitro .

Ibandronate does not undergo hepatic metabolism and does not inhibit the hepatic cytochrome P450 system. Ibandronate is eliminated by renal excretion. Based on a rat study, the ibandronate secretory pathway does not appear to include known acidic or basic transport systems involved in the excretion of other drugs.

Elimination The portion of ibandronate that is not removed from the circulation via bone absorption is eliminated unchanged by the kidney (approximately 50% to 60% of the administered intravenous dose). The plasma elimination of ibandronate is multiphasic. Its renal clearance and distribution into bone accounts for a rapid and early decline in plasma concentrations, reaching 10% of C max within 3 or 8 hours after intravenous or oral administration, respectively.

This is followed by a slower clearance phase as ibandronate redistributes back into the blood from bone. The observed apparent terminal half-life for ibandronate is generally dependent on the dose studied and on assay sensitivity. The observed apparent terminal half-life for intravenous 2 and 4 mg ibandronate after 2 hours of infusion ranges from 4.6 to 15.3 hours and 5 to 25.5 hours, respectively.

Following intravenous administration, total clearance of ibandronate is low, with average values in the range 84 to 160 mL/min. Renal clearance (about 60 mL/min in healthy postmenopausal women) accounts for 50% to 60% of total clearance and is related to creatinine clearance. The difference between the apparent total and renal clearances likely reflects bone uptake of the drug.

Pharmacokinetics in Specific Populations Pediatrics The pharmacokinetics of ibandronate have not been studied in patients less than 18 years of age. Gender The pharmacokinetics of ibandronate are similar in both men and women. Geriatric Since ibandronate is not known to be metabolized, the only difference in ibandronate elimination for geriatric patients versus younger patients is expected to relate to progressive age-related changes in renal function [ see Use in Specific Populations (8.5) ] .

Race Pharmacokinetic differences due to race have not been studied. Renal Impairment Renal clearance of ibandronate in patients with various degrees of renal impairment is linearly related to creatinine clearance (CLcr). Following a single dose of 0.5 mg ibandronate by intravenous administration, patients with creatinine clearance 40 to 70 mL/min had 55% higher exposure (AUC ∞ ) than the exposure observed in patients with creatinine clearance higher than 90 mL/min.

Patients with severe renal impairment (creatinine clearance below 30 mL/min) had more than a two-fold increase in exposure compared to the exposure for patients with creatinine clearance equal to or higher than 80 mL/min [ see Dosage and Administration (2.6) and Use in Specific Populations (8.6) ] . Hepatic Impairment No studies have been performed to assess the pharmacokinetics of ibandronate in patients with hepatic impairment since ibandronate is not metabolized in the human liver. Drug Interaction Melphalan/Prednisolone A pharmacokinetic interaction s… [Excerpted — this section continues on DailyMed.]

12.2Pharmacodynamics In studies of postmenopausal women, ibandronate sodium injection at doses of 0.5 mg to 3 mg produced biochemical changes indicative of inhibition of bone resorption, including decreases of biochemical markers of bone collagen degradation (cross-linked C-telopeptide of Type I collagen [CTX]). Changes in markers of bone formation (osteocalcin) were observed later than changes in resorption markers, as expected, due to the coupled nature of bone resorption and formation. Year 1 results from an efficacy and safety study comparing ibandronate sodium injection 3 mg every 3 months and ibandronate 2.5 mg daily oral tablet demonstrated that both dosing regimens significantly suppressed serum CTX levels at Months 3, 6, and 12.

The median pre-dose or trough serum CTX levels in the intent-to-treat population reached a nadir of 57% (ibandronate sodium injection) and 62% (ibandronate 2.5 mg tablets) below baseline values by Month 6, and remained stable at Month 12 of treatment.

14 CLINICAL STUDIES

14.1Treatment of Postmenopausal Osteoporosis Quarterly Intravenous Injection The effectiveness and safety of ibandronate sodium injection 3 mg once every 3 months were demonstrated in a randomized, double-blind, multinational, noninferiority study in 1358 women with postmenopausal osteoporosis (L2-L4 lumbar spine BMD, T-score below -2.5 SD at baseline). The control group received ibandronate 2.5 mg daily oral tablets. The primary efficacy parameter was the relative change from baseline to 1 year of treatment in lumbar spine BMD, which was compared between the intravenous injection and the daily oral treatment groups.

All patients received 400 international units vitamin D and 500 mg calcium supplementation per day. Effect on BMD In the intent-to-treat (ITT) efficacy analysis, the least-squares mean increase at 1 year in lumbar spine BMD in patients (n = 429) treated with ibandronate sodium injection 3 mg once every 3 months (4.5%) was statistically superior to that in patients (n = 434) treated with daily oral tablets (3.5%). The mean difference between groups was 1.1% (95% confidence interval: 0.5%, 1.6%; p<0.001; see Figure 1 ).

The mean increase from baseline in total hip BMD at 1 year was 2.1% in the ibandronate sodium injection 3 mg once every 3 months group and 1.5% in the ibandronate 2.5 mg daily oral tablet group. Consistently higher BMD increases at the femoral neck and trochanter were also observed following ibandronate sodium injection 3 mg once every 3 months compared to ibandronate 2.5 mg daily oral tablet. Figure 1 Mean Percent Change (95% Confidence Interval) from Baseline in Lumbar Spine BMD at One Year in Patients Treated with Ibandronate 2.5 mg Daily Oral Tablet or Ibandronate Sodium Injectio n 3 mg Once Every 3 Months Bone Histology The histological analysis of bone biopsies after 22 months of treatment with 3 mg intravenous ibandronate every 3 months (n = 30) or 23 months of treatment with 2 mg intravenous ibandronate every 2 months (n = 27) in women with postmenopausal osteoporosis showed bone of normal quality and no indication of a mineralization defect.

Daily Oral Tablets The effectiveness and safety of ibandronate daily oral tablets were demonstrated in a randomized, double-blind, placebo-controlled, multinational study (Treatment Study) of 2946 women aged 55 to 80 years, who were on average 21 years postmenopause, who had a lumbar spine BMD 2 to 5 SD below the premenopausal mean (T-­score) in at least one vertebra [L1-L4], and who had one to four prevalent vertebral fractures. Ibandronate was evaluated at oral doses of 2.5 mg daily and 20 mg intermittently. The main outcome measure was the occurrence of new radiographically diagnosed, vertebral fractures after 3 years of treatment.

The diagnosis of an incident vertebral fracture was based on both qualitative diagnosis by the radiologist and quantitative morphometric criterion. The morphometric criterion required the dual occurrence of two events: a relative height ratio or relative height reduction in a vertebral body of at least 20%, together with at least a 4 mm absolute decrease in height. All women received 400 international units vitamin D and 500 mg calcium supplementation per day.

Effect on Vertebral Fracture Ibandronate 2.5 mg daily oral tablet significantly reduced the incidence of new vertebral fractures compared to placebo. Over the course of the 3-year study, the risk for new vertebral fracture was 9.6% in the placebo-treated women and 4.7% in the women treated with ibandronate 2.5 mg daily oral tablet (p<0.001) (see Table 3 ). Table 3 Effect of Ibandronate Daily Oral Tablet on the Incidence of Vertebral Fracture in the 3-Year Osteoporosis Treatment Study* * The endpoint value is the value at the study’s last time point, 3 years, for all patients who had a fracture identified at that time; otherwise, the last postbaseline value prior to the study’s last time point is used. ** p = 0.0003 vs. placebo *** “Worsening verte… [Excerpted — this section continues on DailyMed.]

13 NONCLINICAL TOXICOLOGY

13.1Carcinogenesis, Mutagenesis, Impairment of Fertility Carcinogenesis In a 104-week carcinogenicity study, doses of 3, 7, or 15 mg/kg/day were administered by oral gavage to Wistar rats (systemic exposures in males and females up to 3 and 1 times, respectively, human exposure). There were no significant drug-related tumor findings in male or female rats. In a 78-week carcinogenicity study, doses of 5, 20, or 40 mg/kg/day were administered by oral gavage to NMRI mice (exposures in males and females up to 96 and 14 times, respectively, human exposure).

There were no significant drug-related tumor findings in male or female mice. In a 90-week carcinogenicity study, doses of 5, 20, or 80 mg/kg/day were administered in the drinking water to NMRI mice. A dose-related increased incidence of adrenal subcapsular adenoma/carcinoma was observed in female mice, which was statistically significant at 80 mg/kg/day (32 to 51 times human exposure).

The relevance of these findings to humans is unknown. Exposure multiples comparing human and rodent doses were calculated using human exposure at the recommended intravenous dose of 3 mg every 3 months, based on cumulative AUC comparison. Mutagenesis There was no evidence for a mutagenic or clastogenic potential of ibandronate in the following assays: in vitro bacterial mutagenesis assay in Salmonella typhimurium and Escherichia coli (Ames test), mammalian cell mutagenesis assay in Chinese hamster V79 cells, and chromosomal aberration test in human peripheral lymphocytes, each with and without metabolic activation.

Ibandronate was not genotoxic in the in vivo mouse micronucleus tests for chromosomal damage. Impairment of Fertility In female rats treated from 14 days prior to mating through gestation, decreases in fertility, corpora lutea and implantation sites, and increased preimplantation loss were observed at an intravenous dose of 1.2 mg/kg/day (117 times human exposure). In male rats treated for 28 days prior to mating, a decrease in sperm production and altered sperm morphology were observed at intravenous doses greater than or equal to 0.3 mg/kg/day (greater than or equal to 40 times human exposure).

Exposure multiples comparing human and rat doses were calculated using human exposure at the recommended intravenous dose of 3 mg every 3 months, based on cumulative AUC comparison.

13.2Animal Pharmacology Animal studies have shown that ibandronate is an inhibitor of osteoclast-mediated bone resorption. In the Schenk assay in growing rats, ibandronate inhibited bone resorption and increased bone volume, based on histologic examination of the tibial metaphyses. There was no evidence of impaired mineralization at the highest dose of 5 mg/kg/day (subcutaneously), which is 1000 times the lowest antiresorptive dose of 0.005 mg/kg/day in this model, and 5000 times the optimal antiresorptive dose of 0.001 mg/kg/day in the aged ovariectomized rat.

This indicates that ibandronate sodium injection administered at a therapeutic dose is unlikely to induce osteomalacia. Long-term daily or intermittent administration of ibandronate to ovariectomized rats or monkeys was associated with suppression of bone turnover and increases in bone mass. Vertebral BMD, trabecular density, and biomechanical strength were increased dose-dependently in rats and monkeys, at doses up to 8 to 4 times the human intravenous dose of 3 mg every 3 months, based on cumulative dose normalized for body surface area (mg/m 2 ) and area under the curve (AUC) comparison, respectively.

Ibandronate maintained the positive correlation between bone mass and strength at the ulna and femoral neck. New bone formed in the presence of ibandronate had normal histologic structure and did not show mineralization defects.