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Fosamax

Clinical Pharmacology
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Clinical Pharmacology

To assess the effects of FOSAMAX on the incidence of vertebral fractures (detected by digitized radiography; approximately one third of these were clinically symptomatic), the U.S. and Multinational studies were combined in an analysis that compared placebo to the pooled dosage groups of FOSAMAX (5 or 10 mg for three years or 20 mg for two years followed by 5 mg for one year). There was a statistically significant reduction in the proportion of patients treated with FOSAMAX experiencing one or more new vertebral fractures relative to those treated with placebo (3.2% vs. 6.2%; a 48% relative risk reduction). A reduction in the total number of new vertebral fractures (4.2 vs. 11.3 per 100 patients) was also observed. In the pooled analysis, patients who received FOSAMAX had a loss in stature that was statistically significantly less than was observed in those who received placebo (-3.0 mm vs. -4.6 mm).

The Fracture Intervention Trial (FIT) consisted of two studies in postmenopausal women: the Three-Year Study of patients who had at least one baseline radiographic vertebral fracture and the Four-Year Study of patients with low bone mass but without a baseline vertebral fracture. In both studies of FIT, 96% of randomized patients completed the studies (i.e., had a closeout visit at the scheduled end of the study); approximately 80% of patients were still taking study medication upon completion. Fracture Intervention Trial: Three-Year Study (patients with at least one baseline radiographic vertebral fracture)

This randomized, double-blind, placebo-controlled, 2027-patient study (FOSAMAX, n=1022; placebo, n=1005) demonstrated that treatment with FOSAMAX resulted in statistically significant reductions in fracture incidence at three years as shown in the table below.

Effect of FOSAMAX on Fracture Incidence in the Three-Year
Study of FIT
(patients with vertebral fracture at baseline)


  Percent of Patients Absolute Reduction in Fracture Incidence Relative Reduction in Fracture Risk %
FOSAMAX
(n=1022)
Placebo
(n=1005)
Patients with:
Vertebral fractures (diagnosed by X- ray)†
≥ 1 new vertebral fracture 7.9 15.0 7.1 47***
≥ 2 new vertebral fractures 0.5 4.9 4.4 90***
Clinical (symptomatic) fractures
Any clinical (symptomatic) fracture 13.8 18.1 4.3 26‡
≥ 1 clinical (symptomatic) vertebral fracture 2.3 5.0 2.7 54**
Hip fracture 1.1 2.2 1.1 51*
Wrist (forearm) fracture 2.2 4.1 1.9 48*
†Number evaluable for vertebral fractures: FOSAMAX, n=984; placebo, n=966 *p<0.05, **p<0.01, ***p<0.001, ‡p=0.007

Furthermore, in this population of patients with baseline vertebral fracture, treatment with FOSAMAX significantly reduced the incidence of hospitalizations (25.0% vs. 30.7%).

In the Three-Year Study of FIT, fractures of the hip occurred in 22 (2.2%) of 1005 patients on placebo and 11 (1.1%) of 1022 patients on FOSAMAX, p=0.047. The figure below displays the cumulative incidence of hip fractures in this study.

Cumulative Incidence of Hip Fractures in the
Three-Year Study of FIT
(patients with radiographic vertebral fracture at baseline)


Cumulative Incidence of Hip Fractures in the Three-Year Study of FIT - illustration
Fracture Intervention Trial: Four-Year Study (patients with low bone mass but without a baseline radiographic vertebral fracture)
Brand Name: Fosamax
Generic Name: Alendronate Sodium
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