What is Fosamax (alendronate)?

Fosamax (alendronate) is a bisphosphonate used for treating osteoporosis (reduced density of bone that leads to fractures) and bone pain from diseases such as:

Off-label uses for Fosamax include vitamin D overdose and osteoporosis caused by spinal injury.

Common side effects of Fosamax include:

Serious side effects of Fosamax include femoral fractures.

Drug interactions of Fosamax include:

Fosamax has not been studied in pregnant women. It is unknown if Fosamax is secreted in human milk. Consult your doctor before breastfeeding

What are the important side effects of Fosamax (alendronate)?

The most common side effect of alendronate is stomach pain.

Other important side effects are:

Fosamax (alendronate) side effects list for healthcare professionals

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

Treatment Of Osteoporosis In Postmenopausal Women

Daily Dosing
  • The safety of Fosamax in the treatment of postmenopausal osteoporosis was assessed in four clinical trials that enrolled 7453 women aged 44-84 years.
  • Study 1 and Study 2 were identically designed, three-year, placebo-controlled, double-blind, multicenter studies (United States and Multinational n=994); Study 3 was the three-year vertebral fracture cohort of the Fracture Intervention Trial [FIT] (n=2027) and Study 4 was the four-year clinical fracture cohort of FIT (n=4432).
  • Overall, 3620 patients were exposed to placebo and 3432 patients exposed to Fosamax.
  • Patients with pre-existing gastrointestinal disease and concomitant use of non-steroidal anti-inflammatory drugs were included in these clinical trials. In Study 1 and Study 2 all women received 500 mg elemental calcium as carbonate.
  • In Study 3 and Study 4 all women with dietary calcium intake less than 1000 mg per day received 500 mg calcium and 250 international units Vitamin D per day.
  • Among patients treated with alendronate 10 mg or placebo in Study 1 and Study 2, and all patients in Study 3 and Study 4, the incidence of all-cause mortality was 1.8% in the placebo group and 1.8% in the Fosamax group.
  • The incidence of serious adverse event was 30.7% in the placebo group and 30.9% in the Fosamax group.
  • The percentage of patients who discontinued the study due to any clinical adverse event was 9.5% in the placebo group and 8.9% in the Fosamax group.
  • Adverse reactions from these studies considered by the investigators as possibly, probably, or definitely drug related in greater than or equal to 1% of patients treated with either Fosamax or placebo are presented in Table 1.

Table 1: Osteoporosis Treatment Studies in Postmenopausal Women Adverse Reactions Considered Possibly, Probably, or Definitely Drug Related by the Investigators and Reported in Greater Than or Equal to 1% of Patients

United States/ Multinational StudiesFracture Intervention Trial
Fosamax*
%
(n=196)
Placebo
%
(n=397)
Fosamax
%
(n=3236)
Placebo
%
(n=3223)
Gastrointestinal
  abdominal pain6.64.81.51.5
  nausea3.64.01.11.5
  dyspepsia3.63.51.11.2
  constipation3.11.80.00.2
  diarrhea3.11.80.60.3
  flatulence2.60.50.20.3
  acid regurgitation2.04.31.10.9
  esophageal ulcer1.50.00.10.1
  vomiting1.01.50.20.3
  dysphagia1.00.00.10.1
  abdominal distention1.00.80.00.0
  gastritis0.51.30.60.7
Musculoskeletal
  musculoskeletal (bone, muscle or joint) pain4.12.50.40.3
  muscle cramp0.01.00.20.1
Nervous
  System/Psychiatric headache2.61.50.20.2
  dizziness0.01.00.00.1
Special Senses
  taste perversion0.51.00.10.0
* 10 mg/day for three years
5 mg/day for 2 years and 10 mg/day for either 1 or 2 additional years

Rash and erythema have occurred.

Gastrointestinal Adverse Reactions

One patient treated with Fosamax (10 mg/day), who had a history of peptic ulcer disease and gastrectomy and who was taking concomitant aspirin, developed an anastomotic ulcer with mild hemorrhage, which was considered drug related. Aspirin and Fosamax were discontinued and the patient recovered.

In the Study 1 and Study 2 populations, 49-54% had a history of gastrointestinal disorders at baseline and 54-89% used nonsteroidal anti-inflammatory drugs or aspirin at some time during the studies.

Laboratory Test Findings

In double-blind, multicenter, controlled studies, asymptomatic, mild, and transient decreases in serum calcium and phosphate were observed in approximately 18% and 10%, respectively, of patients taking Fosamax versus approximately 12% and 3% of those taking placebo. However, the incidences of decreases in serum calcium to less than 8.0 mg/dL (2.0 mM) and serum phosphate to less than or equal to 2.0 mg/dL (0.65 mM) were similar in both treatment groups.

Weekly Dosing

The safety of Fosamax 70 mg once weekly for the treatment of postmenopausal osteoporosis was assessed in a one-year, double-blind, multicenter study comparing Fosamax 70 mg once weekly and Fosamax 10 mg daily. The overall safety and tolerability profiles of once weekly Fosamax 70 mg and Fosamax 10 mg daily were similar. The adverse reactions considered by the investigators as possibly, probably, or definitely drug related in greater than or equal to 1% of patients in either treatment group are presented in Table 2.

Table 2: Osteoporosis Treatment Studies in Postmenopausal WomenAdverse Reactions Considered Possibly, Probably, or Definitely Drug Relatedby the Investigators and Reported in Greater Than or Equal to 1% of Patients

Once Weekly Fosamax
70 mg
%
(n=519)
Fosamax
10 mg/day
%
(n=370)
Gastrointestinal
  abdominal pain3.73.0
  dyspepsia2.72.2
  acid regurgitation1.92.4
  nausea1.92.4
  abdominal distention1.01.4
  constipation0.81.6
  flatulence0.41.6
  gastritis0.21.1
  gastric ulcer0.01.1
Musculoskeletal
  musculoskeletal (bone, muscle, joint) pain2.93.2
  muscle cramp0.21.1

Prevention Of Osteoporosis In Postmenopausal Women

Daily Dosing

The safety of Fosamax 5 mg/day in postmenopausal women 40-60 years of age has been evaluated in three double-blind, placebo-controlled studies involving over 1,400 patients randomized to receive Fosamax for either two or three years.

In these studies the overall safety profiles of Fosamax 5 mg/day and placebo were similar. Discontinuation of therapy due to any clinical adverse event occurred in 7.5% of 642 patients treated with Fosamax 5 mg/day and 5.7% of 648 patients treated with placebo.

Weekly Dosing

The safety of Fosamax 35 mg once weekly compared to Fosamax 5 mg daily was evaluated in a one-year, double-blind, multicenter study of 723 patients. The overall safety and tolerability profiles of once weekly Fosamax 35 mg and Fosamax 5 mg daily were similar.

The adverse reactions from these studies considered by the investigators as possibly, probably, or definitely drug related in greater than or equal to 1% of patients treated with either once weekly Fosamax 35 mg, Fosamax 5 mg/day or placebo are presented in Table 3.

Table 3: Osteoporosis Prevention Studies in Postmenopausal Women Adverse Reactions Considered Possibly, Probably, or Definitely Drug Related by the Investigators and Reported in Greater Than or Equal to 1% of Patients

Two/Three-Year StudiesOne-Year Study
Fosamax
5 mg/day
%
(n=642)
Placebo
%
(n=648)
Fosamax
5 mg/day
%
(n=361)
Once Weekly
Fosamax
35 mg
%
(n=362)
Gastrointestinal
  dyspepsia1.91.42.21.7
  abdominal pain1.73.44.22.2
  acid regurgitation1.42.54.24.7
  nausea1.41.42.51.4
  diarrhea1.11.71.10.6
  constipation0.90.51.70.3
  abdominal distention0.20.31.41.1
Musculoskeletal
  musculoskeletal (bone, muscle or joint) pain0.80.91.92.2

Concomitant Use With Estrogen/Hormone Replacement Therapy

In two studies (of one and two years’ duration) of postmenopausal osteoporotic women (total: n=853), the safety and tolerability profile of combined treatment with Fosamax 10 mg once daily and estrogen ± progestin (n=354) was consistent with those of the individual treatments.

Osteoporosis In Men

In two placebo-controlled, double-blind, multicenter studies in men (a two-year study of Fosamax 10 mg/day and a one-year study of once weekly Fosamax 70 mg) the rates of discontinuation of therapy due to any clinical adverse event were 2.7% for Fosamax 10 mg/day vs. 10.5% for placebo, and 6.4% for once weekly Fosamax 70 mg vs. 8.6% for placebo.

The adverse reactions considered by the investigators as possibly, probably, or definitely drug related in greater than or equal to 2% of patients treated with either Fosamax or placebo are presented in Table 4.

Table 4: Osteoporosis Studies in Men Adverse Reactions Considered Possibly, Probably, or Definitely Drug Related by the Investigators and Reported in Greater Than or Equal to 2% of Patients

Two-year StudyOne-year Study
Fosamax
10 mg/day
%
(n=146)
Placebo
%
(n=95)
Once Weekly
Fosamax 70 mg
%
(n=109)
Placebo
%
(n=58)
Gastrointestinal
  acid regurgitation4.13.20.00.0
  flatulence4.11.10.00.0
  gastroesophageal reflux disease0.73.22.80.0
  dyspepsia3.40.02.81.7
  diarrhea1.41.12.80.0
  abdominal pain2.11.10.93.4
  nausea2.10.00.00.0

Glucocorticoid-Induced Osteoporosis

In two, one-year, placebo-controlled, double-blind, multicenter studies in patients receiving glucocorticoid treatment, the overall safety and tolerability profiles of Fosamax 5 and 10 mg/day were generally similar to that of placebo. The adverse reactions considered by the investigators as possibly, probably, or definitely drug related in greater than or equal to 1% of patients treated with either Fosamax 5 or 10 mg/day or placebo are presented in Table 5.

Table 5: One-Year Studies in Glucocorticoid-Treated Patients Adverse Reactions Considered Possibly, Probably, or Definitely Drug Related by the Investigators and Reported in Greater Than or Equal to 1% of Patients

Fosamax
10 mg/day
%
(n=157)
Fosamax
5 mg/day
%
(n=161)
Placebo
%
(n=159)
Gastrointestinal
  abdominal pain3.21.90.0
  acid regurgitation2.51.91.3
  constipation1.30.60.0
  melena1.30.00.0
  nausea0.61.20.6
  diarrhea0.00.01.3
Nervous System/Psychiatric
  headache0.60.01.3

The overall safety and tolerability profile in the glucocorticoid-induced osteoporosis population that continued therapy for the second year of the studies (Fosamax: n=147) was consistent with that observed in the first year.

Paget's Disease Of Bone
  • In clinical studies (osteoporosis and Paget's disease), adverse events reported in 175 patients taking Fosamax 40 mg/day for 3-12 months were similar to those in postmenopausal women treated with Fosamax 10 mg/day.
  • However, there was an apparent increased incidence of upper gastrointestinal adverse reactions in patients taking Fosamax 40 mg/day (17.7% Fosamax vs. 10.2% placebo). One case of esophagitis and two cases of gastritis resulted in discontinuation of treatment.
  • Additionally, musculoskeletal (bone, muscle or joint) pain, which has been described in patients with Paget's disease treated with other bisphosphonates, was considered by the investigators as possibly, probably, or definitely drug related in approximately 6% of patients treated with Fosamax 40 mg/day versus approximately 1% of patients treated with placebo, but rarely resulted in discontinuation of therapy.
  • Discontinuation of therapy due to any clinical adverse events occurred in 6.4% of patients with Paget's disease treated with Fosamax 40 mg/day and 2.4% of patients treated with placebo.

Post-Marketing Experience

The following adverse reactions have been identified during post-approval use of Fosamax. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Body as a Whole: hypersensitivity reactions including urticaria and angioedema. Transient symptoms of myalgia, malaise, asthenia and fever have been reported with Fosamax, typically in association with initiation of treatment. Symptomatic hypocalcemia has occurred, generally in association with predisposing conditions. Peripheral edema.

Gastrointestinal: esophagitis, esophageal erosions, esophageal ulcers, esophageal stricture or perforation, and oropharyngeal ulceration. Gastric or duodenal ulcers, some severe and with complications, have also been reported.

Localized osteonecrosis of the jaw, generally associated with tooth extraction and/or local infection with delayed healing, has been reported.

Musculoskeletal: bone, joint, and/or muscle pain, occasionally severe, and incapacitating; joint swelling; low-energy femoral shaft and subtrochanteric fractures.

Nervous System: dizziness and vertigo.

Pulmonary: acute asthma exacerbations.

Skin: rash (occasionally with photosensitivity), pruritus, alopecia, severe skin reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis.

Special Senses: uveitis, scleritis or episcleritis. Cholesteatoma of the external auditory canal (focal osteonecrosis).

What drugs interact with Fosamax (alendronate)?

Calcium Supplements/Antacids

Co-administration of Fosamax and calcium, antacids, or oral medications containing multivalent cations will interfere with absorption of Fosamax. Therefore, instruct patients to wait at least one-half hour after taking Fosamax before taking any other oral medications.

Aspirin

In clinical studies, the incidence of upper gastrointestinal adverse events was increased in patients receiving concomitant therapy with daily doses of Fosamax greater than 10 mg and aspirin-containing products.

Nonsteroidal Anti-Inflammatory Drugs

Fosamax may be administered to patients taking nonsteroidal anti-inflammatory drugs (NSAIDs). In a 3-year, controlled, clinical study (n=2027) during which a majority of patients received concomitant NSAIDs, the incidence of upper gastrointestinal adverse events was similar in patients taking Fosamax 5 or 10 mg/day compared to those taking placebo. However, since NSAID use is associated with gastrointestinal irritation, caution should be used during concomitant use with Fosamax.

Summary

Fosamax (alendronate) is a bisphosphonate used for treating osteoporosis (reduced density of bone that leads to fractures) and bone pain from diseases such as metastatic breast cancer, multiple myeloma, and Paget’s disease. Off-label uses for Fosamax include vitamin D overdose and osteoporosis caused by spinal injury. Common side effects of Fosamax include stomach pain, nausea, vomiting, bloating, constipation, diarrhea, gas, black stool (due to intestinal bleeding), change in taste perception, and muscle or joint pain. Serious side effects of Fosamax include femoral fractures. Drug interactions of Fosamax include calcium supplements and antacids, intravenous ranitidine, and aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs). Fosamax has not been studied in pregnant women.It is unknown if Fosamax is secreted in human milk. Consult your doctor before breastfeeding.

Treatment & Diagnosis

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Medically Reviewed on 3/25/2020
References
FDA Prescribing Information
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