Mechanism of Action
ACTONEL has an affinity for hydroxyapatite crystals in bone
and acts as an antiresorptive agent. At the cellular level, ACTONEL inhibits
osteoclasts. The osteoclasts adhere normally to the bone surface, but show
evidence of reduced active resorption (e.g., lack of ruffled border). Histomorphometry
in rats, dogs, and minipigs showed that ACTONEL treatment reduces bone turnover
(activation frequency, i.e., the rate at which bone remodeling sites are
activated) and bone resorption at remodeling sites.
Pharmacodynamics
ACTONEL treatment decreases the elevated rate of bone
turnover that is typically seen in postmenopausal osteoporosis. In clinical
trials, administration of ACTONEL to postmenopausal women resulted in decreases
in biochemical markers of bone turnover, including urinary deoxypyridinoline/creatinine
and urinary collagen cross-linked N-telopeptide (markers of bone resorption)
and serum bone-specific alkaline phosphatase (a marker of bone formation). At
the 5 mg dose, decreases in deoxypyridinoline/creatinine were evident within 14
days of treatment. Changes in bone formation markers were observed later than
changes in resorption markers, as expected, due to the coupled nature of bone
resorption and bone formation; decreases in bone-specific alkaline phosphatase
of about 20% were evident within 3 months of treatment. Bone turnover markers
reached a nadir of about 40% below baseline values by the sixth month of
treatment and remained stable with continued treatment for up to 3 years. Bone
turnover is decreased as early as 14 days and maximally within about 6 months
of treatment, with achievement of a new steady-state that more nearly
approximates the rate of bone turnover seen in premenopausal women. In a 1-year
study comparing daily versus weekly oral dosing regimens of ACTONEL for the treatment
of osteoporosis in postmenopausal women, ACTONEL 5 mg daily and ACTONEL 35 mg
once-a-week decreased urinary collagen crosslinked N-telopeptide by 60% and
61%, respectively. In addition, serum bone-specific alkaline phosphatase was
also reduced by 42% and 41% in the ACTONEL 5 mg daily and ACTONEL 35 mg
once-a-week groups, respectively. When postmenopausal women with osteoporosis
were treated for 1 year with ACTONEL 5 mg daily or ACTONEL 75 mg two
consecutive days per month, urinary collagen cross-linked N-telopeptide was
decreased by 54% and 52%, respectively, and serum bone-specific alkaline
phosphatase was reduced by 36% and 35%, respectively. In a 1–year study
comparing ACTONEL 5 mg daily versus ACTONEL 150 mg once a month in women with
postmenopausal osteoporosis, urinary collagen cross-linked N-telopeptide was
decreased by 52% and 49%, respectively, and serum bone-specific alkaline
phosphatase was reduced by 31% and 32%, respectively.
Osteoporosis in Men
In a 2-year study of men with osteoporosis, treatment with
ACTONEL 35 mg once-aweek resulted in a mean decrease from baseline compared to
placebo of 16% (placebo 20%; ACTONEL 35 mg 37%) for the bone resorption marker
urinary collagen cross-linked Ntelopeptide, 45% (placebo -6%; ACTONEL 35 mg 39%)
for the bone resorption marker serum C-telopeptide, and 27% (placebo -2%;
ACTONEL 35 mg 25%) for the bone formation marker serum bone-specific alkaline
phosphatase.
Glucocorticoid-Induced Osteoporosis
Osteoporosis with glucocorticoid use occurs as a result of
inhibited bone formation and increased bone resorption resulting in net bone
loss. ACTONEL decreases bone resorption without directly inhibiting bone
formation.
In two 1-year clinical trials in the treatment and
prevention of glucocorticoid-induced osteoporosis, ACTONEL 5 mg decreased
urinary collagen cross-linked N-telopeptide (a marker of bone resorption), and
serum bone-specific alkaline phosphatase (a marker of bone formation) by 50% to
55% and 25% to 30%, respectively, within 3 to 6 months after initiation of
therapy.
Paget's Disease
Paget's disease of bone is a chronic, focal skeletal
disorder characterized by greatly increased and disordered bone remodeling.
Excessive osteoclastic bone resorption is followed by osteoblastic new bone
formation, leading to the replacement of the normal bone architecture by
disorganized, enlarged, and weakened bone structure.
In pagetic patients treated with ACTONEL 30 mg daily for 2
months, bone turnover returned to normal in a majority of patients as evidenced
by significant reductions in serum alkaline phosphatase (a marker of bone
formation), and in urinary hydroxyproline/creatinine and
deoxypyridinoline/creatinine (markers of bone resorption).
Pharmacokinetics
Absorption
Based on simultaneous modeling of serum and urine data, peak
absorption after an oral dose is achieved at ~ 1 hour (Tmax) and occurs
throughout the upper gastrointestinal tract. The fraction of the dose absorbed
is independent of dose over the range studied (single dose, from 2.5 mg to 30 mg;
multiple dose, from 2.5 mg to 5 mg). Steady-state conditions in the serum are
observed within 57 days of daily dosing. Mean absolute oral bioavailability of
the 30 mg tablet is 0.63% (90% CI: 0.54% to 0.75%) and is comparable to a
solution.
Food Effect
The extent of absorption of a 30 mg dose (three 10 mg
tablets) when administered 0.5 hours before breakfast is reduced by 55%
compared to dosing in the fasting state (no food or drink for 10 hours prior to
or 4 hours after dosing). Dosing 1 hour prior to breakfast reduces the extent
of absorption by 30% compared to dosing in the fasting state. Dosing either 0.5
hours prior to breakfast or 2 hours after dinner (evening meal) results in a
similar extent of absorption. ACTONEL is effective when administered at least
30 minutes before breakfast.
Distribution
The mean steady-state volume of distribution for risedronate
is 13.8 L/kg in humans. Human plasma protein binding of drug is about 24%.
Preclinical studies in rats and dogs dosed intravenously with single doses of
[14C] risedronate indicate that approximately 60% of the dose is distributed to
bone. The remainder of the dose is excreted in the urine. After multiple oral
dosing in rats, the uptake of risedronate in soft tissues was in the range of
0.001% to 0.01%.
Metabolism
There is no evidence of systemic metabolism of risedronate.
Excretion
In young healthy subjects, approximately half of the
absorbed dose of risedronate was excreted in urine within 24 hours, and 85% of
an intravenous dose was recovered in the urine over 28 days. Based on
simultaneous modeling of serum and urine data, mean renal clearance was 105
mL/min (CV = 34%) and mean total clearance was 122 mL/min (CV = 19%), with the
difference primarily reflecting nonrenal clearance or clearance due to
adsorption to bone. The renal clearance is not concentration dependent, and
there is a linear relationship between renal clearance and creatinine
clearance. Unabsorbed drug is eliminated unchanged in feces. In osteopenic
postmenopausal women, the terminal exponential half-life was 561 hours, mean
renal clearance was 52 mL/min (CV=25%), and mean total clearance was 73 mL/min
(CV=15%).
Specific Populations
Pediatric: ACTONEL is not indicated for use in
pediatric patients (see Pediatric Use).
Gender: Bioavailability and pharmacokinetics
following oral administration are similar in men and women.
Geriatric: Bioavailability and disposition are
similar in elderly ( > 60 years of age) and younger subjects. No dosage
adjustment is necessary.
Race: Pharmacokinetic differences due to race
have not been studied.
Renal Impairment: Risedronate is excreted
unchanged primarily via the kidney. As compared to persons with normal renal
function, the renal clearance of risedronate was decreased by about 70% in patients
with creatinine clearance of approximately 30 mL/min. ACTONEL is not
recommended for use in patients with severe renal impairment (creatinine
clearance < 30 mL/min) because of lack of clinical experience. No dosage
adjustment is necessary in patients with a creatinine clearance ≥ 30
mL/min.
Hepatic Impairment: No studies have been
performed to assess risedronate's safety or efficacy in patients with hepatic
impairment. Risedronate is not metabolized in rat, dog, and human liver
preparations. Insignificant amounts ( < 0.1% of intravenous dose) of drug are
excreted in the bile in rats. Therefore, dosage adjustment is unlikely to be
needed in patients with hepatic impairment.
Drug Interactions: No specific drug-drug
interaction studies were performed. Risedronate is not metabolized and does not
induce or inhibit hepatic microsomal drug-metabolizing enzymes (Cytochrome
P450) [see DRUG INTERACTIONS].
Animal Toxicology and/or Pharmacology
Risedronate demonstrated potent anti-osteoclast,
antiresorptive activity in ovariectomized rats and minipigs. Bone mass and
biomechanical strength were increased dose-dependently at daily oral doses up
to 4 and 25 times the human recommended oral dose of 5 mg for rats and
minipigs, respectively. Risedronate treatment maintained the positive
correlation between BMD and bone strength and did not have a negative effect on
bone structure or mineralization. In intact dogs, risedronate induced positive
bone balance at the level of the bone remodeling unit at oral doses ranging
from 0.5 to 1.5 times the 5 mg/day human daily dose.
In dogs treated with an oral dose approximately 5 times the human
daily dose, risedronate caused a delay in fracture healing of the radius. The
observed delay in fracture healing is similar to other bisphosphonates. This
effect did not occur at a dose approximately 0.5 times the human daily dose.
The Schenk rat assay, based on histologic examination of the
epiphyses of growing rats after drug treatment, demonstrated that risedronate
did not interfere with bone mineralization even at the highest dose tested,
which was approximately 3500 times the lowest antiresorptive dose in this model
(1.5 mcg/kg/day) and approximately 800 times the human daily dose of 5 mg. This
indicates that ACTONEL administered at the therapeutic dose is unlikely to
induce osteomalacia.
Dosing multiples provided above are based on the recommended
human dose of 5 mg/day and normalized using body surface area (mg/m²).
Clinical Studies
Treatment of Osteoporosis in Postmenopausal Women
The fracture efficacy of ACTONEL 5 mg daily in the treatment
of postmenopausal osteoporosis was demonstrated in 2 large, randomized,
placebo-controlled, double-blind studies that enrolled a total of almost 4000
postmenopausal women under similar protocols. The Multinational study (VERT MN) (ACTONEL 5 mg, N = 408) was conducted primarily in Europe and Australia; a second study was conducted in North America (VERT NA) (ACTONEL 5 mg, N = 821). Patients
were selected on the basis of radiographic evidence of previous vertebral
fracture, and therefore, had established disease. The average number of
prevalent vertebral fractures per patient at study entry was 4 in VERT MN, and 2.5 in VERT NA, with a broad range of baseline BMD levels. All patients in
these studies received supplemental calcium 1000 mg/day. Patients with low
25-hydroxyvitamin D3 levels (approximately 40 nmol/L or less) also received
supplemental vitamin D 500 IU/day.
Effect on Vertebral Fractures
Fractures of previously undeformed vertebrae (new fractures)
and worsening of preexisting vertebral fractures were diagnosed
radiographically; some of these fractures were also associated with symptoms
(i.e., clinical fractures). Spinal radiographs were scheduled annually and
prospectively planned analyses were based on the time to a patient's first
diagnosed fracture. The primary endpoint for these studies was the incidence of
new and worsening vertebral fractures across the period of 0 to 3 years.
ACTONEL 5 mg daily significantly reduced the incidence of new and worsening
vertebral fractures and of new vertebral fractures in both VERT NA and VERT MN at all time points (Table 3). The reduction in risk seen in the subgroup of
patients who had 2 or more vertebral fractures at study entry was similar to
that seen in the overall study population.
Table 3 : The Effect of ACTONEL on the Risk of Vertebral
Fractures
| VERT NA |
Proportion of Patients with Fracture (%)a |
|
Placebo
N = 678 |
ACTONEL 5 mg
N = 696 |
Absolute Risk
Reduction (%) |
Relative Risk
Reduction (%) |
| New and Worsening |
| 0 - 1 Year |
7.2 |
3.9 |
3.3 |
49 |
| 0 - 2 Years |
12.8 |
8.0 |
4.8 |
42 |
| 0 - 3 Years |
18.5 |
13.9 |
4.6 |
33 |
| New |
|
|
|
|
| 0 - 1 Year |
6.4 |
2.4 |
4.0 |
65 |
| 0 - 2 Years |
11.7 |
5.8 |
5.9 |
55 |
| 0 - 3 Years |
16.3 |
11.3 |
5.0 |
41 |
| VERT MN |
Placebo
N = 346 |
ACTONEL 5 mg
N = 344 |
Absolute Risk
Reduction (%) |
Relative Risk
Reduction (%) |
| New and Worsening |
| 0 - 1 Year |
15.3 |
8.2 |
7.1 |
50 |
| 0 - 2 Years |
28.3 |
13.9 |
14.4 |
56 |
| 0 - 3 Years |
34.0 |
21.8 |
12.2 |
46 |
| New |
| 0 - 1 Year |
13.3 |
5.6 |
7.7 |
61 |
| 0 - 2 Years |
24.7 |
11.6 |
13.1 |
59 |
| 0 - 3 Years |
29.0 |
18.1 |
10.9 |
49 |
| a Calculated by Kaplan-Meier methodology. |
Effect on Osteoporosis-Related Nonvertebral Fractures
In VERT MN and VERT NA, a prospectively planned efficacy
endpoint was defined consisting of all radiographically confirmed fractures of
skeletal sites accepted as associated with osteoporosis. Fractures at these
sites were collectively referred to as osteoporosis-related nonvertebral
fractures. ACTONEL 5 mg daily significantly reduced the incidence of
nonvertebral osteoporosis-related fractures over 3 years in VERT NA (8% vs. 5%;
relative risk reduction 39%) and reduced the fracture incidence in VERT MN from 16% to 11%. There was a significant reduction from 11% to 7% when the studies
were combined, with a corresponding 36% reduction in relative risk. Figure 1
shows the overall results as well as the results at the individual skeletal
sites for the combined studies.
Figure 1 : Nonvertebral Osteoporosis-Related Fractures Cumulative
Incidence Over 3 Years Combined VERT MN and VERT NA
Effect on Bone Mineral Density
The results of 4 randomized, placebo-controlled trials in
women with postmenopausal osteoporosis (VERT MN, VERT NA, BMD MN, BMD NA)
demonstrate that ACTONEL 5 mg daily increases BMD at the spine, hip, and wrist
compared to the effects seen with placebo. Table 4 displays the significant
increases in BMD seen at the lumbar spine, femoral neck, femoral trochanter,
and midshaft radius in these trials compared to placebo. Thus, overall ACTONEL
reverses the loss of BMD, a central factor in the progression of osteoporosis.
In both VERT studies (VERT MN and VERT NA), ACTONEL 5 mg daily produced
increases in lumbar spine BMD that were progressive over the 3 years of
treatment, and were statistically significant relative to baseline and to
placebo at 6 months and at all later time points.
Table 4 : Mean Percent Increase in BMD from Baseline in Patients
Taking ACTONEL 5 mg or Placebo at Endpointa
| |
VERT MNb |
VERT NAb |
BMD MNc |
BMD NAc |
Placebo
N = 323 |
5 mg
N = 323 |
Placebo
N = 599 |
5 mg
N = 606 |
Placebo
N = 161 |
5 mg
N = 148 |
Placebo
N = 191 |
5 mg
N = 193 |
| Lumbar Spine |
1.0 |
6.6 |
0.8 |
5.0 |
0.0 |
4.0 |
0.2 |
4.8 |
| Femoral Neck |
-1.4 |
1.6 |
-1.0 |
1.4 |
-1.1 |
1.3 |
0.1 |
2.4 |
| Femoral |
-1.9 |
3.9 |
-0.5 |
3.0 |
-0.6 |
2.5 |
1.3 |
4.0 |
| Trochanter |
|
|
|
|
|
|
|
|
| Midshaft Radius |
-1.5* |
0.2* |
-1.2* |
0.1* |
ND |
ND |
a The endpoint value is the value at the study's
last time point for all patients who had BMD measured at that time; otherwise
the last post-baseline BMD value prior to the study's last time point
is used.
b The duration of the studies was 3 years.
c The duration of the studies was 1.5 to 2 years.
* BMD of the midshaft radius was measured in a subset of centers in VERT
MN (placebo, N = 222; 5 mg, N = 214) and VERT NA (placebo, N = 310; 5
mg, N = 306). ND = analysis not done |
ACTONEL 35 mg once-a-week (N = 485) was shown to be
non-inferior to ACTONEL 5 mg daily (N = 480) in a 1-year, double-blind,
multicenter study of postmenopausal women with osteoporosis. In the primary
efficacy analysis of completers, the mean increases from baseline in lumbar
spine BMD at 1 year were 4.0% (3.7, 4.3; 95% confidence interval [CI]) in the 5
mg daily group (N = 391) and 3.9% (3.6, 4.3; 95% CI) in the 35 mg once-a-week
group (N = 387) and the mean difference between 5 mg daily and 35 mg
once-a-week was 0.1% (-0.4, 0.6; 95% CI). The results of the intent-to-treat
analysis with the last observation carried forward were consistent with the
primary efficacy analysis of completers. The 2 treatment groups were also
similar with regard to BMD increases at other skeletal sites.
In a double-blind, multicenter study of postmenopausal women
with osteoporosis, treatment with ACTONEL 75 mg two consecutive days per month
(N = 616) was shown to be non-inferior to ACTONEL 5 mg daily (N = 613). In the
primary efficacy analysis of completers, the mean increases from baseline in
lumbar spine BMD at 1 year were 3.6% (3.3, 3.9; 95% CI) in the 5 mg daily group
(N = 527) and 3.4% (3.1, 3.7; 95% CI) in the 75 mg two days per month group (N
= 524) with a mean difference between groups being 0.2% (-0.2, 0.6; 95% CI).
The results of the intent-to-treat analysis with the last observation carried
forward were consistent with the primary efficacy analysis of completers. The 2
treatment groups were also similar with regard to BMD increases at other
skeletal sites.
ACTONEL 150 mg once-a-month (N = 650) was shown to be
non-inferior to ACTONEL 5 mg daily (N = 642) in a 1-year, double-blind,
multicenter study of postmenopausal women with osteoporosis. The primary
efficacy analysis was conducted in all randomized patients with baseline and
post-baseline lumbar spine BMD values (modified intent-to-treat population)
using last observation carried forward. The mean increases from baseline in
lumbar spine BMD at 1 year were 3.4% (3.0, 3.8; 95% CI) in the 5 mg daily group
(N = 561), and 3.5% (3.1, 3.9; 95% CI) in the 150 mg once-a-month group (N =
578) with a mean difference between groups being -0.1% (-0.5, 0.3; 95% CI). The
results of the completers analysis were consistent with the primary efficacy
analysis. The 2 treatment groups were also similar with regard to BMD increases
at other skeletal sites.
Histology/Histomorphometry
Bone biopsies from 110 postmenopausal women were obtained at
endpoint. Patients had received placebo or daily ACTONEL (2.5 mg or 5 mg) for 2
to 3 years. Histologic evaluation (N = 103) showed no osteomalacia, impaired
bone mineralization, or other adverse effects on bone in ACTONEL-treated women.
These findings demonstrate that bone formed during ACTONEL administration is of
normal quality. The histomorphometric parameter mineralizing surface, an index
of bone turnover, was assessed based upon baseline and post-treatment biopsy
samples from 21 treated with placebo and 23 patients treated with ACTONEL 5 mg.
Mineralizing surface decreased moderately in ACTONEL-treated patients (median
percent change: placebo, -21%; ACTONEL 5 mg, -74%), consistent with the known effects
of treatment on bone turnover.
Effect on Height
In the two 3-year osteoporosis treatment studies, standing
height was measured yearly by stadiometer. Both ACTONEL and placebo-treated
groups lost height during the studies. Patients who received ACTONEL had a
statistically significantly smaller loss of height than those who received
placebo. In VERT MN, the median annual height change was -2.4 mm/yr in the
placebo group compared to -1.3 mm/yr in the ACTONEL 5 mg daily group. In VERT
NA, the median annual height change was -1.1 mm/yr in the placebo group
compared to -0.7 mm/yr in the ACTONEL 5 mg daily group.
Prevention of Osteoporosis in Postmenopausal Women
ACTONEL 5 mg daily prevented bone loss in a majority of
postmenopausal women (age range 42 to 63 years) within 3 years of menopause in
a 2-year, double-blind, placebo-controlled study in 383 patients (ACTONEL 5 mg,
N = 129). All patients in this study received supplemental calcium 1000 mg/day.
Increases in BMD were observed as early as 3 months following initiation of
ACTONEL treatment. ACTONEL 5 mg daily produced significant mean increases in
BMD at the lumbar spine, femoral neck, and trochanter compared to placebo at
the end of the study (Figure 2). ACTONEL 5 mg daily was also effective in patients
with lower baseline lumbar spine BMD (more than 1 SD below the premenopausal
mean) and in those with normal baseline lumbar spine BMD. Bone mineral density
at the distal radius decreased in both ACTONEL and placebo-treated women
following 1 year of treatment.
Figure 2 : Change in BMD from Baseline2-Year Prevention Study
ACTONEL 35 mg once-a-week prevented bone loss in
postmenopausal women (age range 44 to 64 years) without osteoporosis in a
1-year, double-blind, placebo-controlled study in 278 patients (ACTONEL 35 mg,
N = 136). All patients were supplemented with 1000 mg elemental calcium and 400
IU vitamin D per day. The primary efficacy measure was the percent change in
lumbar spine BMD from baseline after 1 year of treatment using LOCF (last observation
carried forward). ACTONEL 35 mg once-a-week resulted in a statistically
significant mean difference from placebo in lumbar spine BMD of +2.9% (least
square mean for placebo -1.05%; risedronate +1.83%). ACTONEL 35 mg once-a-week
also showed a statistically significant mean difference from placebo in BMD at
the total proximal femur of +1.5% (placebo -0.53%; risedronate +1.01%), femoral
neck of +1.2% (placebo -1.00%; risedronate +0.22%), and trochanter of +1.8%
(placebo -0.74%; risedronate +1.07%).
Combined Administration with Hormone Replacement Therapy
The effects of combining ACTONEL 5 mg daily with conjugated
estrogen 0.625 mg daily (N = 263) were compared to the effects of conjugated
estrogen alone (N = 261) in a 1-year, randomized, double-blind study of women
ages 37 to 82 years, who were on average 14 years postmenopausal. The BMD
results for this study are presented in Table 5.
Table 5 : Percent Change from Baseline in BMD After 1 Year
of Treatment
| |
Estrogen 0.625 mg
N =261 |
ACTONEL 5 mg + Estrogen 0.625 mg
N =263 |
| Lumbar Spine |
4.6 ± 0.20 |
5.2 ± 0.23 |
| Femoral Neck |
1.8 ± 0.25 |
2.7 ± 0.25 |
| Femoral Trochanter |
3.2 ± 0.28 |
3.7 ± 0.25 |
| Midshaft Radius |
0.4 ± 0.14 |
0.7 ± 0.17 |
| Distal Radius |
1.7 ± 0.24 |
1.6 ± 0.28 |
| Values shown are mean (±SEM) percent change from
baseline. |
Histology/Histomorphometry
Bone biopsies from 53 postmenopausal women were obtained at
endpoint. Patients had received ACTONEL 5 mg plus estrogen or estrogen alone
once daily for 1 year. Histologic evaluation (N = 47) demonstrated that the bone
of patients treated with ACTONEL plus estrogen was of normal lamellar structure
and normal mineralization. The histomorphometric parameter mineralizing
surface, a measure of bone turnover, was assessed based upon baseline and
posttreatment biopsy samples from 12 patients treated with ACTONEL plus
estrogen and 12 treated with estrogen alone. Mineralizing surface decreased in
both treatment groups (median percent change: ACTONEL plus estrogen, -79%;
estrogen alone, -50%), consistent with the known effects of these agents on
bone turnover.
Men with Osteoporosis
The effects of ACTONEL 35 mg once-a-week on BMD were
examined in a 2-year, double-blind, placebo-controlled, multinational study in
285 men with osteoporosis (ACTONEL, N = 192). The patients had a mean age of
60.6 years (range 36 to 84 years) and 95% were Caucasian. At baseline, mean
lumbar spine T-score was -3.2 and mean femoral neck T-score was -2.4. All
patients in the study had either, 1) a BMD T-score ≤ -2 at the femoral
neck and ≤ -1 at the lumbar spine, or 2) a BMD T-score ≤ -1 at the
femoral neck and ≤ -2.5 at the lumbar spine. All patients were
supplemented with calcium 1000 mg/day and vitamin D 400 to 500 IU/day. ACTONEL
35 mg once-a-week produced significant mean increases in BMD at the lumbar
spine, femoral neck, trochanter, and total hip compared to placebo after 2
years of treatment (treatment difference: lumbar spine, 4.5%; femoral neck,
1.1%; trochanter, 2.2%; total proximal femur, 1.5%).
Glucocorticoid-Induced Osteoporosis
Bone Mineral Density
Two 1-year, double-blind, placebo-controlled trials in
patients who were taking ≥ 7.5 mg/day of prednisone or equivalent
demonstrated that ACTONEL 5 mg daily was effective in the prevention and
treatment of glucocorticoid-induced osteoporosis in men and women who were
either initiating or continuing glucocorticoid therapy. The efficacy of ACTONEL
therapy for glucocorticoid-induced osteoporosis beyond one year has not been
studied.
The prevention study enrolled 228 patients (ACTONEL 5 mg, N
= 76) (18 to 85 years of age), each of whom had initiated glucocorticoid
therapy (mean daily dose of prednisone 21 mg) within the previous 3 months
(mean duration of use prior to study 1.8 months) for rheumatic, skin, and
pulmonary diseases. The mean lumbar spine BMD was normal at baseline (average
T-score -0.7). All patients in this study received supplemental calcium 500
mg/day. By the third month of treatment, and continuing through the year-long
treatment, the placebo group experienced losses in BMD at the lumbar spine,
femoral neck, and trochanter, while BMD was maintained or increased in the
ACTONEL 5 mg group. At each skeletal site there were statistically significant
differences between the placebo group and the ACTONEL 5 mg group at all
timepoints (Months 3, 6, 9, and 12). The treatment differences increased with
continued treatment. Although BMD increased at the distal radius in the ACTONEL
5 mg group compared to the placebo group, the difference was not statistically
significant. The differences between placebo and ACTONEL 5 mg after 1 year were
3.8% at the lumbar spine, 4.1% at the femoral neck, and 4.6% at the trochanter,
as shown in Figure 3. The results at these skeletal sites were similar to the
overall results when the subgroups of men and postmenopausal women, but not
premenopausal women, were analyzed separately. ACTONEL was effective at the
lumbar spine, femoral neck, and trochanter regardless of age ( < 65 vs.
≥ 65), gender, prior and concomitant glucocorticoid dose, or baseline BMD.
Positive treatment effects were also observed in patients taking
glucocorticoids for a broad range of rheumatologic disorders, the most common
of which were rheumatoid arthritis, temporal arteritis, and polymyalgia
rheumatica.
The treatment study of similar design enrolled 290 patients
(ACTONEL 5 mg, N = 100) (19 to 85 years of age) with continuing, long-term
( ≥ 6 months) use of glucocorticoids (mean duration of use prior to study
60 months; mean daily dose of prednisone 15 mg) for rheumatic, skin, and
pulmonary diseases. The baseline mean lumbar spine BMD was low (1.63 SD below
the young healthy population mean), with 28% of the patients more than 2.5 SD
below the mean. All patients in this study received supplemental calcium 1000
mg/day and vitamin D 400 IU/day.
After 1 year of treatment, the BMD of the placebo group was
within ±1% of baseline levels at the lumbar spine, femoral neck, and
trochanter. ACTONEL 5 mg increased BMD at the lumbar spine (2.9%), femoral neck
(1.8%), and trochanter (2.4%). The differences between ACTONEL and placebo were
2.7% at the lumbar spine, 1.9% at the femoral neck, and 1.6% at the trochanter
as shown in Figure 4. The differences were statistically significant for the
lumbar spine and femoral neck, but not at the femoral trochanter. ACTONEL was
similarly effective on lumbar spine BMD regardless of age ( < 65 vs.
≥ 65), gender, or pre-study glucocorticoid dose. Positive treatment
effects were also observed in patients taking glucocorticoids for a broad range
of rheumatologic disorders, the most common of which were rheumatoid arthritis,
temporal arteritis, and polymyalgia rheumatica.
Figure 3 : Change in BMD from BaselinePatients Recently Initiating
Glucocorticoid Therapy
Figure 4 : Change in BMD from BaselinePatients on Long-Term
Glucocorticoid Therapy
Vertebral Fractures
In the prevention study of patients initiating
glucocorticoids, the incidence of vertebral fractures at 1 year was reduced
from 17% in the placebo group to 6% in the ACTONEL group. In the treatment
study of patients continuing glucocorticoids, the incidence of vertebral
fractures was reduced from 15% in the placebo group to 5% in the ACTONEL group
(Figure 5). The statistically significant reduction in vertebral fracture
incidence in the analysis of the combined studies corresponded to an absolute
risk reduction of 11% and a relative risk reduction of 70%. All vertebral
fractures were diagnosed radiographically; some of these fractures also were
associated with symptoms (i.e., clinical fractures).
Figure 5 : Incidence of Vertebral Fractures in Patients Initiating
or Continuing Glucocorticoid Therapy
Histology/Histomorphometry
Bone biopsies from 40 patients on glucocorticoid therapy
were obtained at endpoint. Patients had received placebo or daily ACTONEL (2.5
mg or 5 mg) for 1 year. Histologic evaluation (N = 33) showed that bone formed
during treatment with ACTONEL was of normal lamellar structure and normal
mineralization, with no bone or marrow abnormalities observed. The
histomorphometric parameter mineralizing surface, a measure of bone turnover,
was assessed based upon baseline and post-treatment biopsy samples from 10
patients treated with ACTONEL 5 mg. Mineralizing surface decreased 24% (median
percent change) in these patients. Only a small number of placebo-treated
patients had both baseline and post-treatment biopsy samples, precluding a
meaningful quantitative assessment.
Treatment of Paget's Disease
The efficacy of ACTONEL was demonstrated in 2 clinical
studies involving 120 men and 65 women. In a double-blind, active-controlled
study of patients with moderate-to-severe Paget's disease (serum alkaline
phosphatase levels of at least 2 times the upper limit of normal), patients
were treated with ACTONEL 30 mg daily for 2 months or Didronel® (etidronate
disodium) 400 mg daily for 6 months. At Day 180, 77% (43/56) of ACTONEL-treated
patients achieved normalization of serum alkaline phosphatase levels, compared
to 10.5% (6/57) of patients treated with Didronel (p < 0.001). At Day 540, 16
months after discontinuation of therapy, 53% (17/32) of ACTONEL-treated
patients and 14% (4/29) of Didronel-treated patients with available data
remained in biochemical remission.
During the first 180 days of the active-controlled study,
85% (51/60) of ACTONEL-treated patients demonstrated a ≥ 75% reduction
from baseline in serum alkaline phosphatase excess (difference between measured
level and midpoint of the normal range) with 2 months of treatment compared to
20% (12/60) in the Didronel-treated group with 6 months of treatment
(p < 0.001). Changes in serum alkaline phosphatase excess over time (shown in
Figure 6) were significant following only 30 days of treatment, with a 36%
reduction in serum alkaline phosphatase excess at that time compared to only a
6% reduction seen with Didronel treatment at the same time point (p < 0.01).
Figure 6 : Mean Percent Change from Baseline inSerum Alkaline
Phosphatase Excess by Visit
Response to ACTONEL therapy was similar in patients with
mild to very severe Paget's disease. Table 6 shows the mean percent reduction from
baseline at Day 180 in excess serum alkaline phosphatase in patients with mild,
moderate, or severe disease.
Table 6 : Mean Percent Reduction from Baseline at Day 180
in Total Serum Alkaline Phosphatase Excess by Disease Severity
| Subgroup: Baseline Disease Severity
(AP) |
ACTONEL 30 mg |
DIDRONEL 400 mg |
| n |
Baseline Serum AP (U/L)* |
Mean % Reduction |
n |
Baseline Serum AP (U/L)* |
Mean % Reduction |
| > 2, < 3x ULN |
32 |
271.6 ± 5.3 |
-88.1 |
22 |
277.9 ± 7.45 |
-44.6 |
| ≥ 3, < 7x ULN |
14 |
475.3 ± 28.8 |
-87.5 |
25 |
480.5 ± 26.44 |
-35.0 |
| ≥ 7x ULN |
8 |
1336.5 ± 134.19 |
-81.8 |
6 |
1331.5 ± 167.58 |
-47.2 |
| *Values shown are mean ± SEM; ULN = upper limit of
normal. |
Response to ACTONEL therapy was similar between patients who
had previously received anti-pagetic therapy and those who had not. In the
active-controlled study, 4 patients previously non-responsive to 1 or more courses
of anti-pagetic therapy (calcitonin, Didronel) responded to treatment with
ACTONEL 30 mg daily (defined by at least a 30% change from baseline). Each of
these patients achieved at least 90% reduction from baseline in serum alkaline
phosphatase excess, with 3 patients achieving normalization of serum alkaline
phosphatase levels.
Histomorphometry of the bone was studied in 14 patients with
bone biopsies: 9 patients had biopsies from pagetic bone lesions and 5 patients
from non-pagetic bone. Bone biopsy results in non-pagetic bone did not reveal
osteomalacia, impairment of bone remodeling, or induction of a significant
decline in bone turnover in patients treated with ACTONEL.
Last updated on RxList: 8/7/2009