CLINICAL PHARMACOLOGY
The principal pharmacologic action of pamidronate disodium is inhibition of bone resorption. Although
the mechanism of antiresorptive action is not completely understood, several factors are thought to
contribute to this action. Pamidronate disodium 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, pamidronate disodium inhibits bone
resorption apparently without inhibiting bone formation and mineralization. Of relevance to the treatment
of hypercalcemia of malignancy is the finding that pamidronate disodium 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 pamidronate disodium over 4 hours and 90 mg of pamidronate disodium 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 pamidronate disodium over 4 hours, and 90 mg of
pamidronate disodium 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 pamidronate disodium
infused over 4 hours. The renal clearance of pamidronate in patients was found to closely correlate
with creatinine 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 pamidronate disodium 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 pamidronate disodium 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 pamidronate disodium is administered on a
monthly basis, drug accumulation is not expected. No changes in pamidronate disodium dosing regimen
are recommended for patients with mild to moderate abnormal hepatic function. Pamidronate disodium
has not been studied in patients with severe hepatic impairment.
Drug-Drug Interactions
There are no human pharmacokinetic data for drug interactions with pamidronate disodium.
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 pamidronate disodium, 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 pamidronate
disodium 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 pamidronate disodium,
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 Pamidronate disodium. 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-hormone-related protein, which are elaborated by the tumor and circulate systemically.
Humoral hypercalcemia usually occurs in squamous-cell 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 pamidronate disodium 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 pamidronate disodium were significantly reduced from baseline in all three dosage groups. As a
result, by 7 days after initiation of treatment with pamidronate disodium, 40%, 61%, and 100% of the
patients receiving 30 mg, 60 mg, and 90 mg of pamidronate disodium, respectively, had normalcorrected
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 pamidronate disodium 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
pamidronate disodium and 35 to receive etidronate disodium.
The mean baseline-corrected serum calcium for the pamidronate disodium 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 pamidronate disodium 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 pamidronate disodium group and 65% for the etidronate disodium group (P<0.01).
Mean-corrected serum calcium for the pamidronate disodium 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
pamidronate disodium group and 18% of patients in the etidronate disodium group still had normalcorrected
serum calcium levels, or maintenance of a partial response. For responders in the pamidronate
disodium 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) |
Pamidronate
disodium |
Etidronate
disodium |
PValue* |
Baseline |
14.6 |
13.8 |
|
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 |
*Comparison
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 pamidronate disodium 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 pamidronate disodium 60-mg 4-hour infusion,
pamidronate disodium 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 60-mg 4-hour infusion, 60-mg 24-hour infusion, and saline infusion,
respectively. At Day 14, 39% of the patients in the pamidronate disodium 60-mg 4-hour infusion group
and 26% of the patients in the pamidronate disodium 60-mg 24-hour infusion group had normalcorrected
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 pamidronate
disodium 60-mg 4-hour infusion and pamidronate disodium 60-mg 24-hour infusion, respectively.
In all three trials, patients treated with pamidronate disodium 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 pamidronate disodium 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 pamidronate disodium 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 pamidronate disodium as a single 4-hour infusion on 3
consecutive days, for total doses of 15 mg, 45 mg, and 90 mg of pamidronate disodium.
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 pamidronate disodium 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 pamidronate disodium. 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-tovolume
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 pamidronate disodium or placebo in addition to their underlying antimyeloma
therapy to determine the effect of pamidronate disodium 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 pamidronate disodium or placebo
as a monthly 4-hour intravenous infusion for 9 months. Of the 392 patients, 377 were evaluable for
efficacy (196 pamidronate disodium, 181 placebo). The proportion of patients developing any SRE was
significantly smaller in the pamidronate disodium group (24% vs 41%, P<0.001), and the mean skeletal
morbidity rate (#SRE/year) was significantly smaller for pamidronate disodium 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 pamidronate disodium group (P=.001, .006, and .046,
respectively). Moreover, fewer pamidronate disodium 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
pamidronate disodium 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 pamidronate disodium-treated patients.*
After 21 months, the proportion of patients experiencing any skeletal event remained significantly
smaller in the pamidronate disodium group than the placebo group (P=.015). In addition, the mean
skeletal morbidity rate (#SRE/year) was 1.3 vs 2.2 for pamidronate disodium patients vs placebo patients
(P=.008), and time to first SRE was significantly longer in the pamidronate disodium group compared to
placebo (P=.016). Fewer pamidronate disodium 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
pamidronate disodium 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 pamidronate disodium and 197 to
placebo. 372 patients receiving hormonal therapy were randomized, 182 to pamidronate disodium 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
pamidronate disodium for 24 months. The efficacy results are shown in the table below:
|
Breast Cancer Patients
Receiving Chemotherapy |
Breast Cancer Patients
Receiving Hormonal Therapy |
Any SRE |
Radiation |
Fractures |
Any SRE |
Radiation |
Fractures |
PD |
P |
PD |
P |
PD |
P |
PD |
P |
PD |
P |
PD |
P |
N |
185 |
195 |
185 |
195 |
185 |
195 |
182 |
189 |
182 |
189 |
182 |
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* |
|
PD = Pamidronate Disodium
*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 pamidronate disodium patients and 18% in placebo patients
treated with chemotherapy (P=.001). No difference was seen between pamidronate disodium 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 (Δ) from Baseline at Last Measurement
|
Breast Cancer Patients
Receiving Chemotherapy |
Breast Cancer Patients
Receiving Hormonal Therapy |
PD |
P |
PD vs
P |
PD |
P |
PD vs
P |
N |
Mean
Δ |
N |
Mean
Δ |
PValue* |
N |
Mean
Δ |
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. |
Clinical Studies
Hypercalcemia Of Malignancy
Transient mild elevation of temperature by at least 1°C was noted 24 to 48 hours after administration of
pamidronate disodium in 34% of patients in clinical trials. In the saline trial, 18% of patients had a
temperature elevation of at least 1°C 24 to 48 hours after treatment.
Drug-related local soft-tissue symptoms (redness, swelling or induration and pain on palpation) at the
site of catheter insertion were most common in patients treated with 90 mg of pamidronate disodium.
Symptomatic treatment resulted in rapid resolution in all patients.
Rare cases of uveitis, iritis, scleritis, and episcleritis have been reported, including one case of
scleritis, and one case of uveitis upon separate rechallenges.
Five of 231 patients (2%) who received pamidronate disodium during the four U.S. controlled
hypercalcemia clinical studies were reported to have had seizures, 2 of whom had preexisting seizure
disorders. None of the seizures were considered to be drug-related by the investigators. However, a
possible relationship between the drug and the occurrence of seizures cannot be ruled out. It should be
noted that in the saline arm 1 patient (4%) had a seizure.
There are no controlled clinical trials comparing the efficacy and safety of 90-mg pamidronate
disodium over 24 hours to 2 hours in patients with hypercalcemia of malignancy. However, a
comparison of data from separate clinical trials suggests that the overall safety profile in patients who
received 90-mg pamidronate disodium over 24 hours is similar to those who received 90-mg
pamidronate disodium over 2 hours. The only notable differences observed were an increase in the
proportion of patients in the pamidronate disodium 24-hour group who experienced fluid overload and
electrolyte/ mineral abnormalities.
At least 15% of patients treated with pamidronate disodium for hypercalcemia of malignancy also
experienced the following adverse events during a clinical trial:
General: Fluid overload, generalized pain
Cardiovascular: Hypertension
Gastrointestinal: Abdominal pain, anorexia, constipation, nausea, vomiting
Genitourinary: Urinary tract infection
Musculoskeletal: Bone pain
Laboratory Abnormality: Anemia, hypokalemia, hypomagnesemia, hypophosphatemia
Many of these adverse experiences may have been related to the underlying disease state. The
following table lists the adverse experiences considered to be treatment-related during comparative,
controlled U.S. trials.
Treatment-Related Adverse Experiences Reported in Three U.S.
Controlled Clinical Trials
|
Percent of Patients
Pamidronate Disodium
Injection |
Etidronate
Disodium |
Saline |
60 mg
over 4
hr |
60 mg
over 24
hr |
90 mg
over 24
hr |
7.5 mg/kg
x 3 days |
|
n = 23 |
n = 73 |
n = 17 |
n = 35 |
n = 23 |
General |
Edema |
0 |
1 |
0 |
0 |
0 |
Fatigue |
0 |
0 |
12 |
0 |
0 |
Fever |
26 |
19 |
18 |
9 |
0 |
Fluid overload |
0 |
0 |
0 |
6 |
0 |
Infusion-site
reaction |
0 |
4 |
18 |
0 |
0 |
Moniliasis |
0 |
0 |
6 |
0 |
0 |
Rigors |
0 |
0 |
0 |
0 |
4 |
Gastrointestinal |
Abdominal pain |
0 |
1 |
0 |
0 |
0 |
Anorexia |
4 |
1 |
12 |
0 |
0 |
Constipation |
4 |
0 |
6 |
3 |
0 |
Diarrhea |
0 |
1 |
0 |
0 |
0 |
Dyspepsia |
4 |
0 |
0 |
0 |
0 |
Gastrointestinal
hemorrhage |
0 |
0 |
6 |
0 |
0 |
Nausea |
4 |
0 |
18 |
6 |
0 |
Stomatitis |
0 |
1 |
0 |
3 |
0 |
Vomiting |
4 |
0 |
0 |
0 |
0 |
Respiratory |
Dyspnea |
0 |
0 |
0 |
3 |
0 |
Rales |
0 |
0 |
6 |
0 |
0 |
Rhinitis |
0 |
0 |
6 |
0 |
0 |
Upper respiratory
infection |
0 |
3 |
0 |
0 |
0 |
CNS |
Anxiety |
0 |
0 |
0 |
0 |
4 |
Convulsions |
0 |
0 |
0 |
3 |
0 |
Insomnia |
0 |
1 |
0 |
0 |
0 |
Nervousness |
0 |
0 |
0 |
0 |
4 |
Psychosis |
4 |
0 |
0 |
0 |
0 |
Somnolence |
0 |
1 |
6 |
0 |
0 |
Taste perversion |
0 |
0 |
0 |
3 |
0 |
Cardiovascular |
Atrial fibrillation |
0 |
0 |
6 |
0 |
4 |
Atrial flutter |
0 |
1 |
0 |
0 |
0 |
Cardiac failure |
0 |
1 |
0 |
0 |
0 |
Hypertension |
0 |
0 |
6 |
0 |
4 |
Syncope |
0 |
0 |
6 |
0 |
0 |
Tachycardia |
0 |
0 |
6 |
0 |
4 |
Endocrine |
Hypothyroidism |
0 |
0 |
6 |
0 |
0 |
Hemic and Lymphatic |
Anemia |
0 |
0 |
6 |
0 |
0 |
Leukopenia |
4 |
0 |
0 |
0 |
0 |
Neutropenia |
0 |
1 |
0 |
0 |
0 |
Thrombocytopenia |
0 |
1 |
0 |
0 |
0 |
Musculoskeletal |
Myalgia |
0 |
1 |
0 |
0 |
0 |
Urogenital |
Uremia |
4 |
0 |
0 |
0 |
0 |
Laboratory Abnormalities |
Hypocalcemia |
0 |
1 |
12 |
0 |
0 |
Hypokalemia |
4 |
4 |
18 |
0 |
0 |
Hypomagnesemia |
4 |
10 |
12 |
3 |
4 |
Hypophosphatemia |
0 |
9 |
18 |
3 |
0 |
Abnormal liver
function |
0 |
0 |
0 |
3 |
0 |
Paget's Disease
Transient mild elevation of temperature >1°C above pretreatment baseline was noted within 48 hours
after completion of treatment in 21% of the patients treated with 90 mg of pamidronate disodium in
clinical trials.
Drug-related musculoskeletal pain and nervous system symptoms (dizziness, headache, paresthesia,
increased sweating) were more common in patients with Paget’s disease treated with 90 mg of
pamidronate disodium than in patients with hypercalcemia of malignancy treated with the same dose.
Adverse experiences considered to be related to trial drug, which occurred in at least 5% of patients
with Paget’s disease treated with 90 mg of pamidronate disodium in two U.S. clinical trials, were fever,
nausea, back pain, and bone pain.
At least 10% of all pamidronate disodium-treated patients with Paget’s disease also experienced the
following adverse experiences during clinical trials:
Cardiovascular: Hypertension
Musculoskeletal: Arthrosis, bone pain
Nervous system: Headache
Most of these adverse experiences may have been related to the underlying disease state.
Osteolytic Bone Metastases Of Breast Cancer and Osteolytic Lesions Of Multiple Myeloma
The most commonly reported (>15%) adverse experiences occurred with similar frequencies in the
pamidronate disodium-and placebo-treatment groups, and most of these adverse experiences may have
been related to the underlying disease state or cancer therapy.
Commonly Reported Adverse Experiences in Three U.S. Controlled Clinical Trials
|
Pamidronate
disodium 90 mg
over 4
hours |
Placebo |
Pamidronate
disodium 90 mg
over 2
hours |
Placebo |
All Pamidronate
disodium 90 mg |
Placebo |
N = 205 |
N = 187 |
N = 367 |
N =
386 |
N = 572 |
N = 573 |
% |
% |
% |
% |
% |
% |
General |
Asthenia |
16.1 |
17.1 |
25.6 |
19.2 |
22.2 |
18.5 |
Fatigue |
31.7 |
28.3 |
40.3 |
28.8 |
37.2 |
29 |
Fever |
38.5 |
38 |
38.1 |
32.1 |
38.5 |
34 |
Metastases |
1.0 |
3.0 |
31.3 |
24.4 |
20.5 |
17.5 |
Pain |
13.2 |
11.8 |
15.0 |
18.1 |
14.3 |
16.1 |
Digestive System |
Anorexia |
17.1 |
17.1 |
31.1 |
24.9 |
26.0 |
22.3 |
Constipation |
28.3 |
31.7 |
36.0 |
38.6 |
33.2 |
35.1 |
Diarrhea |
26.8 |
26.8 |
29.4 |
30.6 |
28.5 |
29.7 |
Dyspepsia |
17.6 |
13.4 |
18.3 |
15.0 |
22.6 |
17.5 |
Nausea |
35.6 |
37.4 |
63.5 |
59.1 |
53.5 |
51.8 |
Pain Abdominal |
19.5 |
16.0 |
24.3 |
18.1 |
22.6 |
17.5 |
Vomiting |
16.6 |
19.8 |
46.3 |
39.1 |
35.7 |
32.8 |
Hemic and Lymphatic |
Anemia |
47.8 |
41.7 |
39.5 |
36.8 |
42.5 |
38.4 |
Granulocytopenia |
20.5 |
15.5 |
19.3 |
20.5 |
19.8 |
18.8 |
Thrombocytopenia |
16.6 |
17.1 |
12.5 |
14.0 |
14.0 |
15.0 |
Musculoskeletal System |
Arthralgias |
10.7 |
7.0 |
15.3 |
12.7 |
13.6 |
10.8 |
Myalgia |
25.4 |
15.0 |
26.4 |
22.5 |
26.0 |
20.1 |
Skeletal Pain |
61 |
71.7 |
70 |
75.4 |
66.8 |
74 |
CNS |
Anxiety |
7.8 |
9.1 |
18.0 |
16.8 |
14.3 |
14.3 |
Headache |
24.4 |
19.8 |
27.2 |
23.6 |
26.2 |
22.3 |
Insomnia |
17.1 |
17.2 |
25.1 |
19.4 |
22.2 |
19.0 |
Respiratory System |
Coughing |
26.3 |
22.5 |
25.3 |
19.7 |
25.7 |
20.6 |
Dyspnea |
22.0 |
21.4 |
35.1 |
24.4 |
30.4 |
23.4 |
Pleural Effusion |
2.9 |
4.3 |
15.0 |
9.1 |
10.7 |
7.5 |
Sinusitis |
14.6 |
16.6 |
16.1 |
10.4 |
15.6 |
12.0 |
Upper Respiratory Tract Infection |
32.2 |
28.3 |
19.6 |
20.2 |
24.1 |
22.9 |
Urogenital System |
Urinary Tract
Infection |
15.6 |
9.1 |
20.2 |
17.6 |
18.5 |
15.6 |
Of the toxicities commonly associated with chemotherapy, the frequency of vomiting, anorexia, and
anemia were slightly more common in the pamidronate disodium patients whereas stomatitis and
alopecia occurred at a frequency similar to that in placebo patients. In the breast cancer trials, mild
elevations of serum creatinine occurred in 18.5% of pamidronate disodium patients and 12.3% of
placebo patients. Mineral and electrolyte disturbances, including hypocalcemia, were reported rarely
and in similar percentages of pamidronate disodium-treated patients compared with those in the placebo
group. The reported frequencies of hypocalcemia, hypokalemia, hypophosphatemia, and
hypomagnesemia for pamidronate disodium-treated patients were 3.3%, 10.5%, 1.7%, and 4.4%,
respectively, and for placebo-treated patients were 1.2%, 12%, 1.7%, and 4.5%, respectively. In
previous hypercalcemia of malignancy trials, patients treated with pamidronate disodium (60 or 90 mg
over 24 hours) developed electrolyte abnormalities more frequently (see ADVERSE REACTIONS,
Hypercalcemia Of Malignancy).
Arthralgias and myalgias were reported slightly more frequently in the pamidronate disodium group
than in the placebo group (13.6% and 26% vs 10.8% and 20.1%, respectively).
In multiple myeloma patients, there were five pamidronate disodium-related serious and unexpected
adverse experiences. Four of these were reported during the 12-month extension of the multiple
myeloma trial. Three of the reports were of worsening renal function developing in patients with
progressive multiple myeloma or multiple myeloma-associated amyloidosis. The fourth report was the
adult respiratory distress syndrome developing in a patient recovering from pneumonia and acute
gangrenous cholecystitis. One pamidronate disodium-treated patient experienced an allergic reaction
characterized by swollen and itchy eyes, runny nose, and scratchy throat within 24 hours after the sixth
infusion.
In the breast cancer trials, there were four pamidronate disodium-related adverse experiences, all
moderate in severity, that caused a patient to discontinue participation in the trial. One was due to
interstitial pneumonitis, another to malaise and dyspnea. One pamidronate disodium patient discontinued
the trial due to a symptomatic hypocalcemia. Another pamidronate disodium patient discontinued therapy
due to severe bone pain after each infusion, which the investigator felt was trial-drug-related.
Renal Toxicity
In a study of the safety and efficacy of pamidronate disodium 90 mg (2-hour infusion) vs Zometa 4 mg
(15-minute infusion) in bone metastases patients with multiple myeloma or breast cancer, renal
deterioration was defined as an increase in serum creatinine of 0.5 mg/dL for patients with normal
baseline creatinine (<1.4 mg/dL) or an increase of 1.0 mg/dL for patients with an abnormal baseline
creatinine (≥1.4 mg/dL). The following are data on the incidence of renal deterioration in patients in this
trial. See table below.
Incidence of Renal Function Deterioration in Multiple
Myeloma and Breast Cancer Patients with Normal and
Abnormal Serum Creatinine at Baseline
Patient
Population/
Baseline
Creatinine |
Pamidronate isodium
90 mg/2 hours |
Zometa 4
mg/15 minutes |
n/N |
(%) |
n/N |
(%) |
Normal |
20/246 |
(8.1%) |
23/246 |
(9.3%) |
Abnormal |
2/22 |
(9.1%) |
1/26 |
(3.8%) |
Total |
22/268 |
(8.2%) |
24/272 |
(8.8%) |
*Patients were randomized following the 15 minute infusion
amendment for the Zometa arm. |
Post-Marketing Experience
The following adverse reactions have been reported during post-approval use of pamidronate
disodium. Because these reports are from a population of uncertain size and are subject to confounding
factors, it is not possible to reliably estimate their frequency or establish a causal relationship to drug
exposure.
The following adverse reactions have been reported in post-marketing use: General: reactivation of
Herpes simplex and Herpes zoster, influenza-like symptoms; CNS: confusion and visual hallucinations,
sometimes in the presence of electrolyte imbalance; Skin: rash, pruritus; Special senses: conjunctivitis,
orbital inflammation; Renal and urinary disorders: focal segmental glomerulosclerosis including the
collapsing variant, nephrotic syndrome, renal tubular disorders (RTD), tubulointerstitial nephritis and
glomerulonephropathies; Laboratory abnormalities: hyperkalemia, hypernatremia, hematuria. Rare
instances of allergic manifestations have been reported, including hypotension, dyspnea, or angioedema,
and, very rarely, anaphylactic shock. Pamidronate disodium for Injection USP is contraindicated in
patients with clinically significant hypersensitivity to pamidronate disodium or other bisphosphonates
(see CONTRAINDICATIONS). Respiratory, thoracic and mediastinal disorders: adult respiratory
distress syndrome (ARDS), interstitial lung disease (ILD). Musculoskeletal and connective tissue
disorders: severe and occasionally incapacitating bone, joint, and/or muscle pain.
Cases of osteonecrosis (primarily involving the jaw) have been reported predominantly in cancer
patients treated with intravenous bisphosphonates, including pamidronate disodium. Many of these
patients were also receiving chemotherapy and corticosteroids which may be risk factors for ONJ. Data
suggest a greater frequency of reports of ONJ in certain cancers, such as advanced breast cancer and
multiple myeloma. The majority of the reported cases are in cancer patients following invasive dental
procedures, such as tooth extraction. It is therefore prudent to avoid invasive dental procedures as
recovery may be prolonged. (See PRECAUTIONS.)
Atypical subtrochanteric and diaphyseal femoral fractures have been reported with bisphosphonate
therapy, including pamidronate disodium. (See PRECAUTIONS.)
Animal Toxicology
In both rats and dogs, nephropathy has been associated with intravenous (bolus and infusion)
administration of pamidronate.
Two 7-day intravenous infusion studies were conducted in the dog wherein pamidronate 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.
Pamidronate 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).