The principal pharmacologic action of Aredia is inhibition of bone resorption.
Although the mechanism of antiresorptive action is not completely understood,
several factors are thought to contribute to this action. Aredia adsorbs to
calcium phosphate (hydroxyapatite) crystals in bone and may directly block dissolution
of this mineral component of bone. In vitro studies also suggest that inhibition
of osteoclast activity contributes to inhibition of bone resorption. In animal
studies, at doses recommended for the treatment of hypercalcemia, Aredia inhibits
bone resorption apparently without inhibiting bone formation and mineralization.
Of relevance to the treatment of hypercalcemia of malignancy is the finding
that Aredia inhibits the accelerated bone resorption that results from osteoclast
hyperactivity induced by various tumors in animal studies.
Pharmacokinetics
Cancer patients (n=24) who had minimal or no bony involvement were given an
intravenous infusion of 30, 60, or 90 mg of Aredia over 4 hours and 90 mg of
Aredia over 24 hours (Table 1).
Distribution
The mean ± SD body retention of pamidronate was calculated to be 54
± 16% of the dose over 120 hours.
Metabolism
Pamidronate is not metabolized and is exclusively eliminated by renal excretion.
Excretion
After administration of 30, 60, and 90 mg of Aredia over 4 hours, and 90 mg
of Aredia over 24 hours, an overall mean ± SD of 46 ±16% of the
drug was excreted unchanged in the urine within 120 hours. Cumulative urinary
excretion was linearly related to dose. The mean ± SD elimination half-life
is 28 ± 7 hours. Mean ± SD total and renal clearances of pamidronate
were 107 ± 50 mL/min and 49 ± 28 mL/min, respectively. The rate
of elimination from bone has not been determined.
Special Populations
There are no data available on the effects of age, gender, or race on the pharmacokinetics
of pamidronate.
Pediatric
Pamidronate is not labeled for use in the pediatric population.
Renal Insufficiency
The pharmacokinetics of pamidronate were studied in cancer patients (n=19)
with normal and varying degrees of renal impairment. Each patient received a
single 90-mg dose of Aredia infused over 4 hours. The renal clearance of pamidronate
in patients was found to closely correlate with creatinine8 clearance (see Figure
1). A trend toward a lower percentage of drug excreted unchanged in urine was
observed in renally impaired patients. Adverse experiences noted were not found
to be related to changes in renal clearance of pamidronate. Given the recommended
dose, 90 mg infused over 4 hours, excessive accumulation of pamidronate in renally
impaired patients is not anticipated if Aredia is administered on a monthly
basis.
Figure 1: Pamidronate renal clearance as a function of creatinine
clearance in patients with normal and impaired renal function. The lines are
the mean prediction line and 95% confidence intervals.
Hepatic Insufficiency
The pharmacokinetics of pamidronate were studied in male cancer patients at
risk for bone metastases with normal hepatic function (n=6) and mild to moderate
hepatic dysfunction (n=7). Each patient received a single 90-mg dose of Aredia
infused over 4 hours. Although there was a statistically significant difference
in the pharmacokinetics between patients with normal and impaired hepatic function,
the difference was not considered clinically relevant. Patients with hepatic
impairment exhibited higher mean AUC (53%) and Cmax (29%), and decreased plasma
clearance (33%) values. Nevertheless, pamidronate was still rapidly cleared
from the plasma. Drug levels were not detectable in patients by 12 to 36 hours
after drug infusion. Because Aredia is administered on a monthly basis, drug
accumulation is not expected. No changes in Aredia dosing regimen are recommended
for patients with mild to moderate abnormal hepatic function. Aredia has not
been studied in patients with severe hepatic impairment.
Drug-Drug Interactions
There are no human pharmacokinetic data for drug interactions with Aredia.
Table 1 Mean (SD, CV%) Pamidronate Pharmacokinetic Parameters
in Cancer Patients(n=6 for each group)
Dose
(infusion rate) |
Maximum Concentration
(μg/mL) |
Percent of dose excreted in urine |
Total Clearance
(mL/min) |
Renal Clearance
(mL/min) |
| 30 mg(4 hrs) |
0.73
(0.14, 19.1%) |
43.9
(14.0, 31.9%) |
136
(44, 32.4%) |
58
(27, 46.5%) |
| 60 mg(4 hrs) |
1.44
(0.57, 39.6%) |
47.4
(47.4, 54.4%) |
88
(56, 63.6%) |
42
(28, 66.7%) |
| 90 mg(4 hrs) |
2.61
(0.74, 28.3%) |
45.3
(25.8, 56.9%) |
103
(37, 35.9%) |
44
(16, 36.4%) |
| 90 mg(24 hrs) |
1.38
(1.97, 142.7%) |
47.5
(10.2, 21.5%) |
101
(58, 57.4%) |
52
(42, 80.8%) |
After intravenous administration of radiolabeled pamidronate in rats, approximately
50%-60% of the compound was rapidly adsorbed by bone and slowly eliminated from
the body by the kidneys. In rats given 10 mg/kg bolus injections of radiolabeled
Aredia, approximately 30% of the compound was found in the liver shortly after
administration and was then redistributed to bone or eliminated by the kidneys
over 24-48 hours. Studies in rats injected with radiolabeled Aredia showed that
the compound was rapidly cleared from the circulation and taken up mainly by
bones, liver, spleen, teeth, and tracheal cartilage. Radioactivity was eliminated
from most soft tissues within 1-4 days; was detectable in liver and spleen for
1 and 3 months, respectively; and remained high in bones, trachea, and teeth
for 6 months after dosing. Bone uptake occurred preferentially in areas of high
bone turnover. The terminal phase of elimination half-life in bone was estimated
to be approximately 300 days.
Pharmacodynamics
Serum phosphate levels have been noted to decrease after administration of
Aredia, presumably because of decreased release of phosphate from bone and increased
renal excretion as parathyroid hormone levels, which are usually suppressed
in hypercalcemia associated with malignancy, return toward normal. Phosphate
therapy was administered in 30% of the patients in response to a decrease in
serum phosphate levels. Phosphate levels usually returned toward normal within
7-10 days.
Urinary calcium/creatinine and urinary hydroxyproline/creatinine ratios decrease
and usually return to within or below normal after treatment with Aredia. These
changes occur within the first week after treatment, as do decreases in serum
calcium levels, and are consistent with an antiresorptive pharmacologic action.
Hypercalcemia of Malignancy
Osteoclastic hyperactivity resulting in excessive bone resorption is the underlying
pathophysiologic derangement in metastatic bone disease and hypercalcemia of
malignancy. Excessive release of calcium into the blood as bone is resorbed
results in polyuria and gastrointestinal disturbances, with progressive dehydration
and decreasing glomerular filtration rate. This, in turn, results in increased
renal resorption of calcium, setting up a cycle of worsening systemic hypercalcemia.
Correction of excessive bone resorption and adequate fluid administration to
correct volume deficits are therefore essential to the management of hypercalcemia.
Most cases of hypercalcemia associated with malignancy occur in patients who
have breast cancer; squamous-cell tumors of the lung or head and neck; renal-cell
carcinoma; and certain hematologic malignancies, such as multiple myeloma and
some types of lymphomas. A few less-common malignancies, including vasoactive
intestinal-peptide-producing tumors and cholangiocarcinoma, have a high incidence of hypercalcemia as a metabolic complication. Patients who have hypercalcemia
of malignancy can generally be divided into two groups, according to the pathophysiologic
mechanism involved.
In humoral hypercalcemia, osteoclasts are activated and bone resorption is
stimulated by factors such as parathyroid-hormonerelated protein, which are
elaborated by the tumor and circulate systemically. Humoral hypercalcemia usually
occurs in squamouscell malignancies of the lung or head and neck or in genitourinary
tumors such as renal-cell carcinoma or ovarian cancer. Skeletal metastases may
be absent or minimal in these patients.
Extensive invasion of bone by tumor cells can also result in hypercalcemia
due to local tumor products that stimulate bone resorption by osteoclasts. Tumors
commonly associated with locally mediated hypercalcemia include breast cancer
and multiple myeloma.
Total serum calcium levels in patients who have hypercalcemia of malignancy
may not reflect the severity of hypercalcemia, since concomitant hypoalbuminemia
is commonly present. Ideally, ionized calcium levels should be used to diagnose
and follow hypercalcemic conditions; however, these are not commonly or rapidly
available in many clinical situations. Therefore, adjustment of the total serum
calcium value for differences in albumin levels is often used in place of measurement
of ionized calcium; several nomograms are in use for this type of calculation
(see DOSAGE AND ADMINISTRATION).
Clinical Trials
In one double-blind clinical trial, 52 patients who had hypercalcemia of malignancy
were enrolled to receive 30 mg, 60 mg, or 90 mg of Aredia as a single 24-hour
intravenous infusion if their corrected serum calcium levels were ≥ 12.0 mg/dL
after 48 hours of saline hydration.
The mean baseline-corrected serum calcium for the 30-mg, 60-mg, and 90-mg groups
were 13.8 mg/dL,13.8 mg/dL, and 13.3 mg/ dL, respectively.
The majority of patients (64%) had decreases in albumin-corrected serum calcium
levels by 24 hours after initiation of treatment. Mean-corrected serum calcium
levels at days 2-7 after initiation of treatment with Aredia were significantly
reduced from baseline in all three dosage groups. As a result, by 7 days after
initiation of treatment with Aredia, 40%, 61%, and 100% of the patients receiving
30 mg, 60 mg, and 90 mg of Aredia, respectively, had normal-corrected serum
calcium levels. Many patients (33%-53%) in the 60-mg and 90-mg dosage groups
continued to have normal-corrected serum calcium levels, or a partial response
( ≥ 15% decrease of corrected serum calcium from baseline), at Day 14.
In a second double-blind, controlled clinical trial, 65 cancer patients who
had corrected serum calcium levels of ≥ 12.0 mg/dL after at least 24 hours
of saline hydration were randomized to receive either 60 mg of Aredia as a single
24-hour intravenous infusion or 7.5 mg/kg of etidronate disodium as a 2-hour
intravenous infusion daily for 3 days. Thirty patients were randomized to receive
Aredia and 35 to receive etidronate disodium.
The mean baseline-corrected serum calcium for the Aredia 60-mg and etidronate
disodium groups were 14.6 mg/dL and 13.8 mg/ dL, respectively.
By Day 7, 70% of the patients in the Aredia group and 41% of the patients in
the etidronate disodium group had normal-corrected serum calcium levels (P < 0.05).
When partial responders ( ≥ 15% decrease of serum calcium from baseline) were
also included, the response rates were 97% for the Aredia group and 65% for
the etidronate disodium group (P < 0.01). Mean-corrected serum calcium for
the Aredia and etidronate disodium groups decreased from baseline values to
10.4 and 11.2 mg/dL, respectively, on Day 7. At Day 14, 43% of patients in the
Aredia group and 18% of patients in the etidronate disodium group still had
normal-corrected serum calcium levels, or maintenance of a partial response.
For responders in the Aredia and etidronate disodium groups, the median duration
of response was similar (7 and 5 days, respectively). The time course of effect
on corrected serum calcium is summarized in the following table.
Change in Corrected Serum Calcium by Time from Initiation
of Treatment
| Time(hr) |
Mean Change from Baseline in Corrected Serum
Calcium (mg/dL) |
| Baseline |
Aredia®
14.6 |
Etidronate Disodium
13.8 |
P-Value1 |
| 24 |
-0.3 |
-0.5 |
|
| 48 |
-1.5 |
-1.1 |
|
| 72 |
-2.6 |
-2.0 |
|
| 96 |
-3.5 |
-2.0 |
< 0.01 |
| 168 |
-4.1 |
-2.5 |
< 0.01 |
| 1Comparison between treatment groups |
In a third multicenter, randomized, parallel double-blind trial, a group of
69 cancer patients with hypercalcemia was enrolled to receive 60 mg of Aredia
as a 4- or 24-hour infusion, which was compared to a saline-treatment group.
Patients who had a corrected serum calcium level of ≥ 12.0 mg/dL after 24
hours of saline hydration were eligible for this trial.
The mean baseline-corrected serum calcium levels for Aredia 60-mg 4-hour infusion,
Aredia 60-mg 24-hour infusion, and saline infusion were 14.2 mg/dL, 13.7 mg/dL,
and 13.7 mg/dL, respectively.
By Day 7 after initiation of treatment, 78%, 61%, and 22% of the patients had
normal-corrected serum calcium levels for the 60mg 4-hour infusion, 60-mg 24-hour
infusion, and saline infusion, respectively. At Day 14, 39% of the patients
in the Aredia 60-mg 4hour infusion group and 26% of the patients in the Aredia
60-mg 24-hour infusion group had normal-corrected serum calcium levels or maintenance
of a partial response.
For responders, the median duration of complete responses was 4 days and 6.5
days for Aredia 60-mg 4-hour infusion and Aredia 60-mg 24-hour infusion, respectively.
In all three trials, patients treated with Aredia had similar response rates
in the presence or absence of bone metastases. Concomitant administration of
furosemide did not affect response rates.
Thirty-two patients who had recurrent or refractory hypercalcemia of malignancy
were given a second course of 60 mg of Aredia over a 4- or 24-hour period. Of
these, 41% showed a complete response and 16% showed a partial response to the
retreatment, and these responders had about a 3-mg/dL fall in mean-corrected
serum calcium levels 7 days after retreatment.
In a fourth multicenter, randomized, double-blind trial, 103 patients with
cancer and hypercalcemia (corrected serum calcium ≥ 12.0 mg/dL) received 90
mg of Aredia as a 2-hour infusion. The mean baseline corrected serum calcium
was 14.0 mg/dL. Patients were not required to receive IV hydration prior to
drug administration, but all subjects did receive at least 500 mL of IV saline
hydration concomitantly with the pamidronate infusion. By Day 10 after drug
infusion, 70% of patients had normal corrected serum calcium levels ( < 10.8
mg/dL).
Paget's Disease
Paget's disease of bone (osteitis deformans) is an idiopathic disease characterized
by chronic, focal areas of bone destruction complicated by concurrent excessive
bone repair, affecting one or more bones. These changes result in thickened
but weakened bones that may fracture or bend under stress. Signs and symptoms
may be bone pain, deformity, fractures, neurological disorders resulting from
cranial and spinal nerve entrapment and from spinal cord and brain stem compression,
increased cardiac output to the involved bone, increased serum alkaline phosphatase
levels (reflecting increased bone formation) and/or urine hydroxyproline excretion
(reflecting increased bone resorption).
Clinical Trials
In one double-blind clinical trial, 64 patients with moderate to severe Paget's
disease of bone were enrolled to receive 5 mg, 15 mg, or 30 mg of Aredia as
a single 4-hour infusion on 3 consecutive days, for total doses of 15 mg, 45
mg, and 90 mg of Aredia.
The mean baseline serum alkaline phosphatase levels were 1,409 U/L, 983 U/L,
and 1,085 U/L, and the mean baseline urine hydroxyproline/creatinine ratios
were 0.25, 0.19, and 0.19 for the 15-mg, 45-mg, and 90-mg groups, respectively.
The effects of Aredia on serum alkaline phosphatase (SAP) and urine hydroxyproline/creatinine
ratios (UOHP/C) are summarized in the following table.
Percent of Patients With Significant % Decreases in SAP and
UOHP/C
| SAP |
UOHP/C |
| % Decrease |
15 mg |
45 mg |
90 mg |
15 mg |
45 mg |
90 mg |
| ≥ 50 |
26 |
33 |
60 |
15 |
47 |
72 |
| ≥ 30 |
40 |
65 |
83 |
35 |
57 |
85 |
The median maximum percent decreases from baseline in serum alkaline phosphatase
and urine hydroxyproline/creatinine ratios were 25%, 41%, and 57%, and 25%,
47%, and 61% for the 15-mg, 45-mg, and 90-mg groups, respectively. The median
time to response ( ≥ 50% decrease) for serum alkaline phosphatase was approximately
1 month for the 90-mg group, and the response duration ranged from 1 to 372
days.
No statistically significant differences between treatment groups, or statistically
significant changes from baseline were observed for the bone pain response,
mobility, and global evaluation in the 45-mg and 90-mg groups. Improvement in
radiologic lesions occurred in some patients in the 90-mg group.
Twenty-five patients who had Paget's disease were retreated with 90 mg of Aredia.
Of these, 44% had a ≥ 50% decrease in serum alkaline phosphatase from baseline
after treatment, and 39% had a ≥ 50% decrease in urine hydroxyproline/creatinine
ratio from baseline after treatment.
Osteolytic Bone Metastases of Breast Cancer and Osteolytic Lesions of Multiple
Myeloma
Osteolytic bone metastases commonly occur in patients with multiple myeloma
or breast cancer. These cancers demonstrate a phenomenon known as osteotropism,
meaning they possess an extraordinary affinity for bone. The distribution of
osteolytic bone metastases in these cancers is predominantly in the axial skeleton,
particularly the spine, pelvis, and ribs, rather than the appendicular skeleton,
although lesions in the proximal femur and humerus are not uncommon. This distribution
is similar to the red bone marrow in which slow blood flow possibly assists
attachment of metastatic cells. The surface-to-volume ratio of trabecular bone
is much higher than cortical bone, and therefore disease processes tend to occur
more floridly in trabecular bone than at sites of cortical tissue.
These bone changes can result in patients having evidence of osteolytic skeletal
destruction leading to severe bone pain that requires either radiation therapy
or narcotic analgesics (or both) for symptomatic relief. These changes also
cause pathologic fractures of bone in both the axial and appendicular skeleton.
Axial skeletal fractures of the vertebral bodies may lead to spinal cord compression
or vertebral body collapse with significant neurologic complications. Also,
patients may experience episode(s) of hypercalcemia.
Clinical Trials
In a double-blind, randomized, placebo-controlled trial, 392 patients with
advanced multiple myeloma were enrolled to receive Aredia or placebo in addition
to their underlying antimyeloma therapy to determine the effect of Aredia on
the occurrence of skeletal-related events (SREs). SREs were defined as episodes
of pathologic fractures, radiation therapy to bone, surgery to bone, and spinal
cord compression. Patients received either 90 mg of Aredia or placebo as a monthly
4-hour intravenous infusion for 9 months. Of the 392 patients, 377 were evaluable
for efficacy (196 Aredia, 181 placebo). The proportion of patients developing
any SRE was significantly smaller in the Aredia group (24% vs 41%, P < 0.001),
and the mean skeletal morbidity rate (#SRE/year) was significantly smaller for
Aredia patients than for placebo patients (mean: 1.1 vs 2.1, P < .02). The
times to the first SRE occurrence, pathologic fracture, and radiation to bone
were significantly longer in the Aredia group (P=.001, .006, and .046, respectively).
Moreover, fewer Aredia patients suffered any pathologic fracture (17% vs 30%,
P=.004) or needed radiation to bone (14% vs 22%, P=.049).
In addition, decreases in pain scores from baseline occurred at the last measurement
for those Aredia patients with pain at baseline (P=.026) but not in the placebo
group. At the last measurement, a worsening from baseline was observed in the
placebo group for the Spitzer quality of life variable (P < .001) and ECOG
performance status (P < .011) while there was no significant deterioration
from baseline in these parameters observed in Aredia-treated patients.*
After 21 months, the proportion of patients experiencing any skeletal event
remained significantly smaller in the Aredia group than the placebo group (P=.015).
In addition, the mean skeletal morbidity rate (#SRE/year) was 1.3 vs 2.2 for
Aredia patients vs placebo patients (P=.008), and time to first SRE was significantly
longer in the Aredia group compared to placebo (P=.016). Fewer Aredia patients
suffered vertebral pathologic fractures (16% vs 27%, P=.005). Survival of all
patients was not different between treatment groups.
Two double-blind, randomized, placebo-controlled trials compared the safety
and efficacy of 90 mg of Aredia infused over 2 hours every 3 to 4 weeks for
24 months to that of placebo in preventing SREs in breast cancer patients with
osteolytic bone metastases who had one or more predominantly lytic metastases
of at least 1 cm in diameter: one in patients being treated with antineoplastic
chemotherapy and the second in patients being treated with hormonal antineoplastic
therapy at trial entry.
382 patients receiving chemotherapy were randomized, 185 to Aredia and 197
to placebo. 372 patients receiving hormonal therapy were randomized, 182 to
Aredia and 190 to placebo. All but three patients were evaluable for efficacy.
Patients were followed for 24 months of therapy or until they went off study.
Median duration of follow-up was 13 months in patients receiving chemotherapy
and 17 months in patients receiving hormone therapy. Twenty-five percent of
the patients in the chemotherapy study and 37% of the patients in the hormone
therapy study received Aredia for 24 months. The efficacy results are shown
in the table below:
| N |
Breast Cancer Patients Receiving Chemotherapy |
Breast Cancer Patients Receiving Hormonal
Therapy |
| Any SRE |
Radiation |
Fractures |
Any SRE |
Radiation |
Fractures |
A
185 |
P
195 |
A
185 |
P
195 |
A
185 |
P
195 |
A
182 |
P
189 |
A
182 |
P
189 |
A
182 |
P
189 |
| Skeletal Morbidity Rate (#SRE/year) Mean |
2.5 |
3.7 |
0.8 |
1.3 |
1.6 |
2.2 |
2.4 |
3.6 |
0.6 |
1.2 |
1.6 |
2.2 |
| P-Value |
< .001 |
< .001† |
.018† |
.021 |
.013† |
.040† |
| Proportion of patients having an SRE |
46% |
65% |
28% |
45% |
36% |
49% |
55% |
63% |
31% |
40% |
45% |
55% |
| P-Value |
< .001 |
< .001† |
.014† |
.094 |
.058† |
.054† |
| Median Time to SRE (months) |
13.9 |
7.0 |
NR** |
14.2 |
25.8 |
13.3 |
10.9 |
7.4 |
NR** |
23.4 |
20.6 |
12.8 |
| P-Value |
< .001 |
< .001† |
.009† |
.118 |
.016† |
.113† |
†Fractures and radiation to bone
were two of several secondary endpoints. The statistical significance
of these analyses may be overestimated since numerous analyses were performed.
**NR = Not Reached. |
Bone lesion response was radiographically assessed at baseline and at 3, 6,
and 12 months. The complete + partial response rate was 33% in Aredia patients
and 18% in placebo patients treated with chemotherapy (P=.001). No difference
was seen between Aredia and placebo in hormonally-treated patients.
Pain and analgesic scores, ECOG performance status and Spitzer quality of life
index were measured at baseline and periodically during the trials. The changes
from baseline to the last measurement carried forward are shown in the following
table:
Mean Change (#) from Baseline at Last Measurement
| |
Breast Cancer Patients Receiving Chemotherapy |
Breast Cancer PatientsReceiving Hormonal
Therapy |
| Aredia® |
Placebo |
A vs P |
Aredia® |
Placebo |
A vs P |
| N |
Mean # |
N |
Mean Δ |
P-Value* |
N |
Mean # |
N |
Mean Δ |
P-Value* |
| Pain Score |
175 |
+0.93 |
183 |
+1.69 |
.050 |
173 |
+0.50 |
179 |
+1.60 |
.007 |
| Analgesic Score |
175 |
+0.74 |
183 |
+1.55 |
.009 |
173 |
+0.90 |
179 |
+2.28 |
< .001 |
| ECOG PS |
178 |
+0.81 |
186 |
+1.19 |
.002 |
175 |
+0.95 |
182 |
+0.90 |
.773 |
| Spitzer QOL |
177 |
-1.76 |
185 |
-2.21 |
.103 |
173 |
-1.86 |
181 |
-2.05 |
.409 |
Decreases in pain, analgesic scores and
ECOG PS, and increases in Spitzer QOL indicate an improvement from baseline.
*The statistical significance of analyses of these secondary endpoints
of pain, quality of life, and performance status in all three trials may
be overestimated since numerous analyses were performed. |
Animal Toxicology
In both rats and dogs, nephropathy has been associated with intravenous (bolus
and infusion) administration of Aredia.
Two 7-day intravenous infusion studies were conducted in the dog wherein Aredia
was given for 1, 4, or 24 hours at doses of 1-20 mg/kg for up to 7 days. In
the first study, the compound was well tolerated at 3 mg/kg (1.7 x highest recommended
human dose [HRHD] for a single intravenous infusion) when administered for 4
or 24 hours, but renal findings such as elevated BUN and creatinine levels and
renal tubular necrosis occurred when 3 mg/kg was infused for 1 hour and at doses
of ≥ 10 mg/kg. In the second study, slight renal tubular necrosis was observed
in 1 male at 1 mg/kg when infused for 4 hours. Additional findings included
elevated BUN levels in several treated animals and renal tubular dilation and/or
inflammation at ≥ 1 mg/kg after each infusion time.
Aredia was given to rats at doses of 2, 6, and 20 mg/kg and to dogs at doses
of 2, 4, 6, and 20 mg/kg as a 1-hour infusion, once a week, for 3 months followed
by a 1-month recovery period. In rats, nephrotoxicity was observed at ≥ 6
mg/kg and included increased
BUN and creatinine levels and tubular degeneration and necrosis. These findings
were still present at 20 mg/kg at the end of the recovery period. In dogs, moribundity/death
and renal toxicity occurred at 20 mg/kg as did kidney findings of elevated BUN
and creatinine levels at ≥ 6 mg/kg and renal tubular degeneration at ≥ 4
mg/kg. The kidney changes were partially reversible at 6 mg/kg. In both studies,
the dose level that produced no adverse renal effects was considered to be 2
mg/kg (1.1 x HRHD for a single intravenous infusion).
Last updated on RxList: 2/12/2009