Zoledronic Acid for Injection Concentrate - Pharmaceutical Information, Clinical Trials, Detailed Pharmacology, Toxicology.
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Zoledronic Acid for Injection Concentrate - Scientific Information

Manufacture: Dr. Reddy's Laboratories Inc
Country: India
Condition: Bone Metastases (Osteolytic Bone Metastases of Solid Tumors), Bone Metastases of Breast Cancer (Breast Cancer, Bone Metastases), Hypercalcemia, Myeloma, Multiple (Multiple Myeloma), Osteolytic Bone Metastases of Solid Tumors, Osteolytic Bone Lesions of Multiple Myeloma, Prostate Cancer
Class: Bisphosphonates
Form: Liquid solution, Intravenous (IV)
Ingredients: mannitol, USP, as bulking agent, water for injection, and sodium citrate, USP, as buffering agent

Pharmaceutical Information

Drug Substance

Proper name: Zoledronic acid monohydrate
Chemical name: (1-Hydroxy-2-(1-imidazol) ethylene-1, 1-diphosphonic acid monohydrate
Molecular formula: C5H10N2O7P2.H2O
Molecular weight: 290 g/mol
Structural formula:
Physicochemical properties:
Description: White to almost white crystalline solid
Solubility: Sparingly soluble in 0.1N NaOH
pH: The pH of a 0.7% aqueous solution of zoledronic acid in water is between 1.5 and 2.5

Clinical Trials

Tumor-Induced Hypercalcaemia

Two identical multicenter, randomized, double-blind, double-dummy studies of zoledronic acid for injection 4 mg given as a 5-minute infusion or pamidronate disodium for injection 90 mg given as a 2-hour infusion were conducted in patients with tumour-induced hypercalcaemia (TIH).Note: Administration of zoledronic acid for injection 4 mg given as a 5-minute intravenous infusion has been shown to result in an increased risk of renal toxicity, as measured by increases in serum creatinine, which can progress to renal failure. The incidence of renal toxicity and renal failure has been shown to be reduced when zoledronic acid for injection 4 mg is given as a 15-minute intravenous infusion over no less than 15 minutes. (see Warnings and Precautions and Dosage and Administration). TIH was defined as corrected serum calcium (CSC) concentration of ≥ 12.0 mg/dL (3.00 mmol/L). The primary efficacy variable was the proportion of patients having a complete response, defined as the lowering of the CSC to ≤ 10.8 mg/dL (2.70 mmol/L) within ten days after drug infusion. Each treatment group was considered efficacious if the lower bound of the 95% confidence interval for the proportion of complete responders was >70%. This was achieved for the zoledronic acid for injection 4 mg group in each study, but not for the pamidronate disodium for injection 90 mg group. To assess the effects of zoledronic acid for injection versus those of pamidronate disodium for injection, the two multicenter TIH studies were combined in a pre-planned analysis. The results showed that zoledronic acid for injection 4 mg was statistically superior to pamidronate disodium for injection 90 mg for the proportion of complete responders at day 7 and day 10. The results also demonstrated a faster normalization of CSC by day 7 for zoledronic acid for injection 4 mg.

The following response rates were observed (Table 1):

Table 1 - Proportion of Complete Responders by Day in pooled TIH studies
Day 4 Day 7 Day 10
Zoledronic Acid for Injection 4 mg (N=86) 45.3% (p=0.104) 82.6% (p=0.005) 88.4% (p=0.002)
Pamidronate Disodium for Injection 90 mg (N=99) 33.3% 63.6% 69.7%

P-values vs. pamidronate disodium for injection 90 mg based on Cochran-Mantel Haenszel adjusting for baseline CSC

Secondary efficacy variables, time to relapse and duration of complete response, were also assessed. Time to relapse was defined as the duration (in days) from study infusion until the last CSC value ≤ 11.6 mg/dL (2.90 mmol/L). Patients who did not have a complete response were assigned a time to relapse of 0 days. Duration of complete response was defined as the duration (in days) from the occurrence of a complete response until the last CSC ≤ 10.8 mg/dL (2.70 mmol/L).The results showed that zoledronic acid for injection 4 mg had a statistically longer time to relapse than pamidronate disodium for injection.

Table 2 - Results for Secondary Efficacy Variables in pooled TIH studies

Zoledronic Acid for
Injection 4 mg
Pamidronate
Disodium for
Injection 90 mg
N Median
(days)
P-value N Median
(days)
Time to relapse 86 30 0 99 17
Duration of complete response 76 32 NA 69 18

P-values vs. pamidronate disodium for injection 90 mg based on Cox regression adjusted for baseline CSC
NA: Duration of complete response was not analyzed in the subset of complete responders

Bone Metastases of Solid Tumours and Osteolytic Lesions of Multiple Myeloma

Three randomized, controlled trials in patients with bone metastases of solid tumours and osteolytic lesions of multiple myeloma were conducted with zoledronic acid for injection. The planned duration of therapy in the core studies were 15 months in the trial in patients with prostate cancer, 13 months in the trial in patients with breast cancer and multiple myeloma, and 9 months in the trial in patients with lung cancer and other solid tumours. In addition, an extension phase was included in each trial in order to primarily determine the safety of long-term exposure to zoledronic acid for injection. Patients who successfully completed the primary core phase of treatment were given the option to extend treatment for a total of 24 months (prostate cancer), 25 months (breast cancer and multiple myeloma), and 21 months (lung and other solid tumours). In the trials with patients with breast cancer and multiple myeloma, and in patients with lung cancer and other solid tumours, only the core phase was reported for efficacy as a high percentage of patients did not choose to participate in the extension phase.

The studies were amended twice because of renal toxicity. The zoledronic acid for injection infusion duration was increased from 5 minutes to 15 minutes. After all patients had been accrued, but while dosing and follow-up continued, patients in the 8-mg zoledronic acid for injection treatment arm were switched to 4 mg. Patients who were randomized to the zoledronic acid for injection 8-mg group are not included in these analyses.

Each study evaluated skeletal-related events (SREs), defined as any of the following: pathologic fracture (vertebral or non-vertebral), radiation therapy to bone (including the use of radioisotopes), surgery to bone or spinal cord compression. A change in antineoplastic therapy due to increased pain was considered as an SRE in the prostate cancer study only. Planned analyses included the proportion of patients with an SRE during the core phase of the study (the primary efficacy endpoint) and main secondary efficacy endpoints including time to the first SRE (i.e. the hazard ratio for the first occurrence of an SRE not taking death into consideration (censoring deaths), and multiple event analysis. Multiple event analysis using the Andersen-Gill approach was performed to evaluate the overall effect of zoledronic acid for injection on the occurrence of skeletal complications. This analysis takes into account all clinically meaningful events experienced by the study patients, and considers the total number of events experienced as well as the time from randomization to each event. However, the assumptions required for this analysis are strong and it is difficult to assess whether the data meet the assumptions. For the multiple event analysis, events that occurred in close proximity were counted as one event.

Radiation therapy to bone and pathological fractures were the most common type of skeletal related events.

Bone Metastases Due to Prostate Cancer

In a phase III randomized, double-blind trial, zoledronic acid for injection was compared to placebo for the prevention of Skeletal Related Events (SREs) in prostate cancer patients with bone metastases. A total of 422 patients (214 zoledronic acid for injection 4 mg, 208 placebo) with metastatic bone disease from prostate cancer with a rising serum PSA despite hormonal treatment were randomized to receive either zoledronic acid for injection 4 mg administered over 15 minutes or placebo every 3 weeks. The primary efficacy variable was the proportion of patients having an SRE at 15 months. The proportion of patients experiencing at least one SRE (33% for zoledronic acid for injection 4 mg vs. 44% for placebo, p = 0.02) demonstrated statistically significant superiority for zoledronic acid for injection vs. placebo.( See Figure 1).

Figure 1

Zoledronic acid for injection was superior to placebo for time to first SRE at 15 months (hazard ratio of 0.67, 95% CI: 0.49, 0.91), median of 321 days for placebo vs. median not reached for zoledronic acid for injection 4 mg. zoledronic acid for injection demonstrated a statistically significant superiority over placebo for time to fracture (p= 0.01).

In addition, of the 146 (81 zoledronic acid for injection, 65 placebo) patients who completed the core phase of the trial, 132 (74 zoledronic acid for injection, 58 placebo) consented to enter the extension phase and 85 (49 zoledronic acid for injection and 36 placebo) completed it. At 24 months, the zoledronic acid for injection 4 mg group had a significantly lower proportion of patients experiencing at least one SRE (of all patients initially randomized) when compared with placebo (38% for zoledronic acid for injection 4 mg, 49% for placebo, p=0.03). No adjustments to the p-values for the two analysis time points were made. The multiple event analysis indicated that prostate cancer patients receiving zoledronic acid for injection 4 mg had a 36% overall reduction in risk (hazard ratio of 0.64, 95% CI: 0.485, 0.84; p=0.002) for skeletal complications compared to placebo over the course of the trial. See Table 3 for the results of the main secondary efficacy analyses.

Table 3 - Results of main secondary efficacy variables (Core + Extension Phase)
Prostate Cancer Patient
All SRE Core Phase Core + Extension Ph
Zoledronic Acid
for Injection
4 mg
Placebo Zoledronic
Acid for
Injection
4 mg
Placebo
N 214 208 214 208
Time to First SRE
Hazard Ratio (95% CI) vs. placebo 0.67 (0.49, 0.91) 0.68 (0.50, 0.91)
Median Time to SRE§ (days) n.r.§§ 321 488 321
P-Value 0.01 0.01
Multiple Event Analysis
Hazard Ratio (95% CI) vs. placebo 0.64 (0.47, 0.87) 0.64 (0.48, 0.84)
P-Value 0.004 0.002

§ Median Time to first SRE not taking death into consideration (i.e. deaths were censored).
§§ Not reached.
p-values vs. placebo based on Cox-regression stratified by presence of distant metastases at initial diagnosis or not.

Bone Metastases from Breast Cancer and Osteolytic Lesions of Multiple Myeloma

The second phase III randomized, double-blind trial was designed to demonstrate comparable efficacy of zoledronic acid for injection 4 mg to pamidronate disodium for injection 90 mg. A total of 1116 patients (561 zoledronic acid for injection 4 mg, 555 pamidronate disodium for injection 90 mg) with either Durie-Salmon Stage III multiple myeloma or Stage IV breast cancer with at least one bone lesion were treated with zoledronic acid for injection 4 mg via 15-minute intravenous (IV) infusion or pamidronate disodium for injection 90 mg via 2-hour IV infusion every 3 to 4 weeks. The primary efficacy endpoint was the proportion of patients experiencing at least one skeletal-related event (SRE) at 13 months. The proportion of patients with an SRE was 44% and 46% for zoledronic acid for injection 4 mg and pamidronate disodium for injection 90 mg, respectively (p=0.46) (See Figure 2).

Figure 2

Zoledronic acid for injection was demonstrated to be comparable to pamidronate disodium for injection in efficacy for the endpoint of the proportion of patients with an SRE in a non-inferiority analysis. There were no significant differences between zoledronic acid for injection and pamidronate disodium for injection in time to first SRE.

The multiple event analysis indicated that patients with breast cancer and multiple myeloma receiving zoledronic acid for injection 4 mg in this trial had an 11.5% overall reduction in risk (hazard ratio of 0.88, 95% CI: 0.75, 1.05; p =0.15) for skeletal complications, compared to patients receiving pamidronate disodium for injection 90 mg over the core phase of the trial. See Table 4 for the results of the main secondary efficacy analyses.

Table 4 - Results of main secondary efficacy variables (Core Phase)
Breast Cancer and Multiple Myeloma Patients All SRE
Zoledronic Acid
for Injection
4 mg
Pamidronate
Disodium for
Injection
90 mg
N 561 363
Time to First SRE
Hazard Ratio (95% CI) vs. pamidronate disodium for injection 90 mg 0.91 (0.77, 1.09)
Median Time to SRE§(days) 373 363
P-Value 0.32
Multiple Event Analysis
Hazard Ratio (95% CI) vs. pamidronate disodium for injection 90 mg 0.88 (0.75, 1.05)
P-Value 0.15

§ Median Time to first SRE not taking death into consideration (i.e. deaths were censored).
p-value vs. pamidronate disodium for injection 90 mg based on Cox-regression stratified by cancer type.

In addition, of the 690 (353 zoledronic acid for injection, 337 pamidronate disodium for injection) patients who completed the core phase of the trial, 417 (212 zoledronic acid for injection, 205 pamidronate disodium for injection) consented to enter the extension phase. Another 111 patients continued with open-label pamidronate disodium for injection which at the time was the standard of care. A total of 246 (123 zoledronic acid for injection, 123 pamidronate disodium for injection) patients completed the extension phase. In the extension phase, only the safety data are reported (see Adverse Reactions).

Bone Metastases From Breast Cancer: Placebo-Controlled Trial in Japanese Patients

Zoledronic acid for injection was also studied in a double-blind, randomized, placebo-controlled, Phase III trial in 228 patients with documented bone metastases from breast cancer to evaluate the effect of zoledronic acid for injection on the skeletal related event (SRE) rate ratio, calculated as the total number of SRE events (excluding hypercalcaemia and adjusted for prior fracture), divided by the total risk period. Patients received either 4 mg zoledronic acid for injection or placebo every four weeks for one year. Patients were evenly distributed between zoledronic acid for injection-treated and placebo groups.

The SRE rate ratio at one year was 0.61, indicating that treatment with zoledronic acid for injection reduced the rate of occurrence of SREs by 39% compared with placebo (p=0.027). The proportion of patients with at least one SRE (excluding hypercalcaemia) was 29.8% in the zoledronic acid for injection-treated group versus 49.6% in the placebo group (p=0.003). Median time to onset of the first SRE was not reached in the zoledronic acid for injection-treated arm at the end of the study and was significantly prolonged compared to placebo (p=0.007). zoledronic acid for injection reduced the risk of SREs by 41% in a multiple event analysis (risk ratio=0.59, p=0.019) compared with placebo.

Figure 3 - Time to onset of the first SRE (–TIH)

In the zoledronic acid for injection-treated group, decreases in pain scores from baseline (using the Brief Pain Inventory, BPI) occurred from 4 weeks onwards and at every subsequent time point during the study, while the pain score in the placebo group remained unchanged or increased from baseline (Figure 4). zoledronic acid for injection inhibited the worsening of the analgesic score more than placebo. In addition, 71.8% of zoledronic acid for injection-treated patients versus 63.1% of placebo patients showed improvement or no change in the Eastern Cooperative Oncology Group (ECOG) performance score at the final observation.

Figure 4 - Mean change from baseline in Brief Pain Inventory (BPI) pain scores by treatment group and time on study.

Bone Metastases From Solid Tumours Other Than Breast Cancer or Prostate Cancer

A third phase III randomized, double-blind, placebo-controlled trial compared zoledronic acid for injection to placebo for the prevention of SREs in patients who had solid tumours other than breast cancer or prostate cancer, with osteolytic or mixed bone metastases.Patients had to have at least 1 lytic metastasis for study entry. A total of 257 patients were randomized to zoledronic acid for injection 4 mg; 134 patients with non-small cell lung cancer (NSCLC) and 123 with other solid tumours (OST). A total of 250 patients were randomized to placebo (130 patients with NSCLC, 120 with OST). Patients received either an intravenous infusion of zoledronic acid for injection 4 mg or placebo every 3 weeks. The primary efficacy variable was the proportion of patients having an SRE at nine months. At nine months, the zoledronic acid for injection 4 mg group had a lower proportion of patients experiencing an SRE when compared with placebo (38% for zoledronic acid for injection 4 mg, 44% for placebo, p=0.13), see Figure 5.The difference for the primary efficacy variable was not statistically significant. However, when tumour-induced hypercalcaemia (TIH) was also included as an SRE, the proportion of patients having an SRE reached statistical significance favouring zoledronic acid for injection 4 mg over placebo (38% for zoledronic acid for injection 4 mg and 47% for placebo, p=0.04).

Study patients had a median overall survival of 6 months. Zoledronic acid for injection extended the median time to an SRE by greater than two months (67 days) [median of 230 days vs. 163 days, p = 0.02. See Table 5].

The multiple event analysis indicated that patients with lung cancer and other solid tumours (other than breast cancer or prostate cancer) receiving zoledronic acid for injection 4 mg had a 27% overall reduction in risk (hazard ratio of 0.73, 95% CI: 0.57, 0.95; p=0.02) for skeletal complications compared to placebo over the core phase of the trial. See Table 4 for the results of the main secondary efficacy analyses.

Table 5 - Results of main secondary efficacy variables (Core Phase) NSCLC and OST Patients All SRE (-TIH)

Zoledronic
Acid for
Injection
4 mg
Placebo
N 257 250
Time to First SRE
Hazard Ratio (95% CI) vs. placebo 0.73 (0.55, 0.96)
Median Time to SRE§ (days) 230 163
P-Value 0.02
Multiple Event Analysis
Hazard ratio (95% CI) vs. placebo 0.73 (0.57, 0.95)
P-Value 0.02

§ Median Time to first SRE not taking death into consideration (i.e. deaths were censored).
p-value vs. placebo based on Cox-regression stratified by cancer type.

In addition, of the 131 (68 zoledronic acid for injection, 63 placebo) patients who completed the core phase of the trial, 69 (34 zoledronic acid for injection, 35 placebo) consented to enter the extension phase and 16 (8 zoledronic acid for injection, 8 placebo) completed it. In the extension phase, only the safety data are reported (see Adverse Reactions).

Detailed Pharmacology

Zoledronic acid for injection belongs to a highly potent class of bisphosphonates which act specifically on bone. It is an inhibitor of osteoclastic bone resorption.

The selective action of bisphosphonates on bone is based on their high affinity for mineralized bone, but the precise molecular mechanism leading to the inhibition of osteoclastic activity is still unclear. In a variety of preclinical assays of bone metabolism, zoledronic acid inhibits bone resorption in vitro at concentrations of 0.3-30 nM, and in vivo at doses of 0.3-30 µg/kg without exerting any untoward effects on either bone formation or mineralization.

In addition to inhibiting osteoclastic bone resorption, zoledronic acid for injection exerts direct anti-tumour effects on cultured human myeloma and breast cancer cells, inhibiting proliferation and inducing apoptosis. It also inhibits human endothelial cell proliferation in vitro and is anti-angiogenic in animals. Moreover, the observation that zoledronic acid for injection reduces the invasion of human breast cancer cells through extracellular matrix in vitro indicates that it may possibly have anti-metastatic properties.

In broad safety screening, no adverse effects were detected on the cardiovascular or central nervous systems at pharmacologically relevant doses for the inhibition of bone resorption.

Toxicology

Acute Toxicity

Species Route Doses
(mg/kg)
Findings
Rat i.v. 0.6, 6, 30, 60, 80 > 6 mg/kg: mortality and clinical signs
6 mg/kg: renal findings
LD50 = approximately 13 mg/kg
Rat i.v. 1.6, 8, 16, 32 > 8 mg/kg: mortality, clinical signs, necropsy findings in kidney, liver, GI tract
> 1.6 mg/kg: ↓ BW, FC, injection site irritation max. non lethal dose: 1.6 mg/kg
min. lethal dose: 8 mg/kg
Dog i.v. 2.10 2 mg/kg: no clinical signs
10 mg/kg: mortality
Mouse s.c. 10.50 10 mg/kg: no clinical signs
50 mg/kg: mortality, clinical signs
LD50 = 10-50 mg/kg in males and > 10 mg/kg in females
Rat p.o. 200, 2000 > 200 mg/kg:↓ FC,BW, clinical signs, necropsy findings in stomach: enlarged, red lesions
2000 mg/kg: 100% mortality

The acute parenteral toxicity of zoledronic acid was moderate to marked in the mouse, rat and dog. The estimated LD50 in the mouse (s.c.) and rat (i.v.) was 10-50 mg/kg (males)/>10 mg/kg (females) and 13 mg/kg (males), respectively. Compound-related renal tubular lesions were observed in the rat after one dose at 6 mg/kg. A single intravenous injection in the dog produced clinical signs, intestinal haemorrhage and mortality after 6 days in one male at 10 mg/kg. The other male received 2 mg/kg and survived the 14-day post-dose observation period without clinical signs.

Subacute and Chronic Toxicity

Study Type Species Route Doses (mg/kg) Findings
Intravenous
10-Day range-Finding Rat i.v. 0.06, 0.6, 6 0.06 mg/kg: well tolerated
0.6 mg/kg: clin. signs; micro in kidneys, liver
6 mg/kg: sacrifice due to severe clin. signs; micro in bone, kidneys, stomach, liver, thymus, spleen, lymph nodes
NOAEL: 0.06 mg/kg
2-Week Rat i.v. 0.06, 0.6, 3.2 (every third day for 18 days) ≥ 0.06 mg/kg: local irritation, non-proliferative hyperostosis
≥ 0.6 mg/kg: gastric lesions
3.2 mg/kg: mortality, clin signs; ↓BW/FC, clin lab alterations, ↑adrenal, kidney, liver wgts, nephropathy, hepatocellular hypertrophy
NOAEL: not established
10-Day range-Finding Dog i.v. 0,1, 1 ≥ 0.1 mg/kg: micro in bone rib, injection sites
1 mg/kg: clin. signs; micro findings in stomach, intestine, liver, lung, thymus
NOAEL: 0.1 mg/kg
4-Week + 1 mo. Recovery Dog i.v. 0.02, 0.06, 0.2 ≥ 0.06 mg/kg: clinical signs 0.2 mg/kg: clin. signs; micro in GI tract
NOAEL: 0.02 mg/kg
3-Month + 1 mo. Recovery Dog i.v. 0.01,0.03, 0.1→0.2 ≥ 0.01 mg/kg: genital tract atrophy (F); ↑primary spongiosa in bone; splenic histiocytosis; lung inflammation, thymic atrophy
≥ 0.03 mg/kg: moribund sacrifice at 0.1 → 0.2 mg/kg due to inj. site irritation, ↓
BW/FC,↑ ALAT/ASAT, ↓ bone AP, PO4, creatinine and ↓ RBC indices; inj. site ulceration, kidney lesions, genital tract (M) & pancreatic atrophy, inflammation of urinary bladder, esophagus, stomach and liver.
NOAEL: not established
26/52-wk+ 6 mo. Recovery Dog i.v. 0.005,0.03, 0.1 All doses: inj site irritation; ↓ phosphate; non-proliferative hyperostosis ≥0.03 mg/kg: micro in kidneys, GI tract; ↑ BUN,↑ total protein.
0.1 mg/kg: ↓ creatinine, ↑ ASAT, ↓Ca.
NOAEL: 0.005 mg/kg
Bone analyses
 (26/52-wk + 6 mo. Recovery)
Dog i.v. 0.005,0.03, 0.1 All biomechanical parameters assessing bone quality showed either no deleterious effect or an increase in quality at pharmacologically efficacious doses.
Subcutaneous
10-Day range-finding Rat s.c. 0.2,0.6,2 2 mg/kg: clin. signs; microscopic changes in kidneys, liver; spleen, thymus, lymph nodes, lung and adrenals.
≥0.6 mg/kg: clin. signs
1-Month + 1 mo recovery Rat s.c. 0.02,0.06,0.2 ≥ 0.2 mg/kg: Local irritation at the injection sites
0.2 mg/kg: swelling at injection site; clin. signs; micro findings in liver, lymph nodes
≥0.06 mg/kg: clin. signs; micro findings of spleen, injection sites, skeletal muscle;
NOAEL: 0.02 mg/kg
3-Month + 1 mo recovery Rat s.c. 0.01,0.03,0.1 Tolerated without mortality at doses up to and including 0.1 mg/kg. Non-proliferative hyperostosis. NOAEL 0.01 mg/kg in females. No NOAEL in males due to reduced BW/FC at all doses.
6/12-Month + 6 mo recovery Rat s.c. 0.001,0.003, 0.01 ≥0.001 mg/kg: ↓ bone AP, ↑ reticulocyte count, splenic hemosiderosis and congestion, ↑ splenic hematopoiesis, ↑ cellularity of femoral/tibial marrow, non-proliferative hyperostosis. Following bone morphometry, no deleterious effects after administration for 12 months.
≥ 0.003 mg/kg: ↓ RBC parameters, ↑ fibrinogen, renal tubular changes, progressive nephropathy.
0.01 mg/kg: testicular tubular atrophy
Bone morphometry on bone (tibia) did not reveal deleterious effects
NOAEL: 0.001 mg/kg
Oral
13-week Mouse p.o. 0, 0.3, 3, 10, 30→20 0.3 - 30→20 mg/kg: mortality; respiratory signs; ↓FC; non-proliferative hyperostosis
3 - 30→20 mg/kg: ↓BW; laryngeal, tracheal & bronchial inflammation
10-Day range-finding Rat p.o. 1,10,100 1 and 10 mg/kg: well-tolerated
100 mg/kg: mortality & moribund sacrifice after 1 wk; clin. signs; gastritis, GI tract necrosis, acute renal tubular lesions, liver changes; lymphoid depletion spleen, thymus.
1-Month +1 mo recovery Rat p.o. 62060 6 mg/kg: well-tolerated
≥ 20 mg/kg: clin signs; liver, spleen, lymph nodes
60 mg/kg: mortality; GI tract, kidneys, salivary glands, thymus, adrenal, lung, trachea
NOAEL: 6 mg/kg
6-Month + 1 mo recovery Rat p.o. 0.1,1, 10 ≥ 0.1 mg/kg: bone
≥ 1 mg/kg: clin signs
10 mg/kg: mortality
NOAEL: 0.1 mg/kg
10-Day Dog p.o. 1→30, 10 (for 9d); 30 (for 10d) a 1 → 30 mg/kg: clin. signs; micro findings in kidneys, esophagus, liver; non-proliferative hyperostosis.
10 mg/kg: no significant findings
1-Month Dog p.o. 3,10, 30 ≥ 3 mg/kg: clin signs
≥ 10 mg/kg: mortality; liver, lung, thymus
30 mg/kg: gingiva, pancreas, adrenals
6-Month +1 mo. recovery Dog p.o. 0.01, 0.1, 1 Well-tolerated at doses of up to 1 mg/kg. Histological bone changes were considered pharmacologic NOAEL: 1 mg/kg

a From day 9 of dosing: 30 mg/kg for an additional 10 days

Reproductive Toxicity Studies

Zoledronic acid was evaluated for potential adverse effects on fertility, labour, delivery and lactation of the parental generation rats as well as development, behaviour and fertility of the F1 generation at doses of 0.01, 0.03 and 0.1 mg/kg; however, many females in the treated groups either died or were sacrificed while moribund at parturition due to difficulty in delivery (dystocia) such that the study was terminated on lactation day 7.

Teratology studies were performed in two species, both via subcutaneous administration zoledronic acid. Teratogenicity was observed in the rat at doses ≥ 0.2 mg/kg as manifested by external, visceral and skeletal malformations. There were also dose-related increases in the incidence of poor skeletal ossification at ≥ 0.2 mg/kg and evidence of maternal toxicity at ≥ 0.2 mg/kg as well as foetal toxicity at 0.4 mg/kg. In the rabbit, reduced number of litters with viable foetuses, increased post- implantation loss and total resorption were observed at 0.1 mg/kg. Fatality was shown in dams with decreased serum calcium level at all doses.

Study
Type
Species Route Doses (mg/kg) Findings
Segment I Rat s.c. 0.01, 0.03, 0.1 ≥ 0.01: maternal toxicity and severe effects on parturition such that the study was terminated on lactation day 7.
Segment II Rat range - finding s.c. 0.2, 0.6, 2 ≥ 0.2 mg/kg: irritation at injection site
≥ 0.6 mg/kg: ↓ maternal BW. 9/10 dams with total resorption (embryo/foetal death) of progeny; remaining dam w/ only 2 foetuses (one with cleft palate).
Segment II Rat s.c. 0.1, 0.2, 0.4 ≥ 0.2 mg/kg: ↓ maternal BW; ↓ foetal wgt; anomalies of viscera and/or skeleton w/ wavy ribs & delay in skeletal maturation.
0.4 mg/kg: 9/24 dams with total resorption of foetuses; some foetuses with oedema, cleft palate, short lower jaw, abnormal ossification
Segment II Rabbit range - finding (pregnant) s.c. 0.1,0.2,0.4 0.2, 0.4 mg/kg: early termination due to severe clinical signs/toxicity.
0.1 mg/kg: Reduced foetal weight; foetal visceral and skeletal development were not examined.
Segment II Rabbit s.c. 0,01, 0.03, 0.1 Maternal toxicity at ≥ 0.01 mg/kg due to ↓ blood calcium.
Reduced number of litters with viable foetuses, increased post-implantation loss and total resorption at 0.1 mg/kg.
Foetal/embryo development abnormalities cannot be assessed due to an insufficient exposure in the surviving dams.

Carcinogenicity

Zoledronic acid was administered orally (gavage) to rats and mice for at least 104 weeks without evidence of carcinogenic potential. Chronic parenteral administration was not feasible given the potential of the compound to cause severe local irritation, often after only one or several doses. As zoledronic acid, and bisphosphonates in general, manifest poor oral bioavailability, fasting procedures were instituted to facilitate absorption. Nevertheless the pharmacological bone changes typically observed following long term bisphosphonate administration (non-proliferative hyperostosis) to young animals with growing skeletons gave clear evidence of systemic exposure to zoledronic acid in both species at all doses. An increased incidence of Harderian gland adenomas/adenocarcinomas was observed in males at 0.1 and 1.0 mg/kg and females at doses ≥ 0.3 mg/kg. These increases were not considered to be related to zoledronic acid administration or biologically meaningful as the Harderian gland is a unique, highly specialized organ which is not present or known to have any correlate in humans; thus, it has no relevance.

Species Route Doses (mg/kg) Findings
Mouse p.o. 0.1,0.3,1.0 ≥ 0.1 mg/kg: non-proliferative hyperostosis
≥ 0.3 mg/kg: ↓BW
Rat p.o. 0.1,0.5,2.0 ≥ 0.1 mg/kg: non-proliferative hyperostosis
≥ 0.5 mg/kg: ↓ BW,FC
2.0 mg/kg: ↑ extramedullary hematopoiesis

Mutagenicity

Study Type Findings
in vitro: Amesa, Amesb, Amesc
Range: a 5000 μg/plate (-S9/+S9), b390 - 25000 μg/plate, c1250 μg/plate (-S9/+S9)
Negative
in vitro: Cytogenetics test on Chinese hamster cells
Range: 9.7 - 1250 μg/mL
Negative
in vitro: Gene mutation test using V79 Chinese hamster cells
Range: 2 - 15 μg/mL
Negative
in vivo: Micronucleus in rats
Range: 2.6 - 10.4 mg/kg
Negative

a Bacterial test systems (S. typhimurium), with/without metabolic activation.
b Batch control
c Bacterial test system (S. typhimurium/ E. coli), with/without metabolic activation.

There was no evidence of mutagenicity for zoledronic acid in a battery of tests covering various endpoints of genotoxicity.