Does Forteo (teriparatide) cause side effects?

Forteo (teriparatide) is a man-made form of parathyroid hormone used to treat osteoporosis, a bone disease that over time causes bones to become fragile and more likely to break. 

Forteo is similar to human parathyroid hormone (PTH) and is made using recombinant DNA (rDNA) technology. PTH is naturally produced by the body and is the key regulator of calcium and phosphate metabolism in the bone and kidney. 

Calcium and phosphate are the main minerals necessary for bone health. PTH also increases the absorption of calcium in the intestines. Forteo binds to the same receptors as natural PTH and mimics the favorable effects of PTH on bone health. 

Beneficial effects of Forteo in osteoporosis treatment include reduced bone turnover, formation of new bone, and increased bone mineral density and bone strength.

Common side effects of Forteo include

Serious side effects of Forteo include

  • a drop in blood pressure when getting up from a sitting or lying position (orthostatic hypotension),
  • increased blood calcium levels,
  • increased blood uric acid levels, and
  • increased calcium levels in urine. 

Drug interactions of Forteo include digoxin, because Forteo increases calcium in the blood and high levels of calcium may increase the risk for digoxin associated side effects. Forteo injection should be used cautiously with other medicines that may increase calcium in the blood. 

There are no available data on Forteo use in pregnant women to evaluate for drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes. Consider discontinuing Forteo when pregnancy is recognized. 

It is unknown if Forteo is excreted in breast milk, affects milk production, or has effects on a breastfed infant. Because of the potential for osteosarcoma shown with Forteo in animal studies, breastfeeding is not recommended during treatment with Forteo.

What are the important side effects of Forteo (teriparatide)?

The most common side effects of Forteo are

Forteo can cause some serious side effects including a drop in blood pressure when getting up from a sitting or lying position (orthostatic hypotension) and increased calcium in the blood.

In animal studies some rats developed osteosarcoma, a type of bone cancer. Osteosarcoma is a rare but serious form of cancer rarely reported in patients taking Forteo. To investigate if Forteo increases the risk of osteosarcoma, a voluntary patient registry has been developed. Patients can get more information about this registry by calling 1-866-382-6813 or visiting www.Forteoregistry.rti.org.

Possible serious side effects or adverse events:

  • Patients with Paget's disease of bone, pediatric and young adult patients with open epiphyses (ends of long bones that are still growing), and patients with prior external beam or implant radiation involving the skeleton should not receive Forteo.
  • Forteo should not be used for more than 2 years in a patient's lifetime and should not be given to patients with bone cancer, history of skeletal cancer, metabolic bone diseases other than osteoporosis, or hypercalcemic disorders.
  • Forteo may increase blood levels of calcium and uric acid. It may also increase calcium levels in urine.

Forteo (teriparatide) side effects list for healthcare professionals

Clinical Trials Experience

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

Treatment Of Osteoporosis In Men And Postmenopausal Women

  • The safety of Forteo in the treatment of osteoporosis in men and postmenopausal women was assessed in two randomized, double-blind, placebo-controlled trials of 1382 patients (21% men, 79% women) aged 28 to 86 years (mean 67 years).
  • The median durations of the trials were 11 months for men and 19 months for women, with 691 patients exposed to Forteo and 691 patients to placebo.
  • All patients received 1000 mg of calcium plus at least 400 IU of vitamin D supplementation per day.
  • The incidence of all cause mortality was 1% in the Forteo group and 1% in the placebo group.
  • The incidence of serious adverse events was 16% in Forteo patients and 19% in placebo patients.
  • Early discontinuation due to adverse events occurred in 7% of Forteo patients and 6% of placebo patients.
  • Table 1 lists adverse events from the two principal osteoporosis trials in men and postmenopausal women that occurred in ≥2% of Forteo-treated and more frequently than placebo-treated patients.

Table 1. Percentage of Patients with Adverse Events Reported by at Least 2% of Forteo-Treated Patients and in More Forteo-Treated Patients than Placebo-Treated Patients from the Two Principal Osteoporosis Trials in Women and Men Adverse Events are Shown Without Attribution of Causality

Forteo
N=691
Placebo
N=691
Event Classification(%)(%)
Body as a Whole
Pain21.320.5
Headache7.57.4
Asthenia8.76.8
Neck pain3.02.7
Cardiovascular
Hypertension7.16.8
Angina pectoris2.51.6
Syncope2.61.4
Digestive System
Nausea8.56.7
Constipation5.44.5
Diarrhea5.14.6
Dyspepsia5.24.1
Vomiting3.02.3
Gastrointestinal disorder2.32.0
Tooth disorder2.01.3
Musculoskeletal
Arthralgia10.18.4
Leg cramps2.61.3
Nervous System
Dizziness8.05.4
Depression4.12.7
Insomnia4.33.6
Vertigo3.82.7
Respiratory System
Rhinitis9.68.8
Cough increased6.45.5
Pharyngitis5.54.8
Dyspnea3.62.6
Pneumonia3.93.3
Skin and Appendages
Rash4.94.5
Sweating2.21.7

Immunogenicity
  • In the clinical trial, antibodies that cross-reacted with teriparatide were detected in 3% of women (15/541) receiving Forteo.
  • Generally, antibodies were first detected following 12 months of treatment and diminished after withdrawal of therapy.
  • There was no evidence of hypersensitivity reactions or allergic reactions among these patients.
  • Antibody formation did not appear to have effects on serum calcium, or on bone mineral density (BMD) response.

Laboratory Findings

Serum Calcium
  • Forteo transiently increased serum calcium, with the maximal effect observed at approximately 4 to 6 hours post-dose.
  • Serum calcium measured at least 16 hours post-dose was not different from pretreatment levels.
  • In clinical trials, the frequency of at least 1 episode of transient hypercalcemia in the 4 to 6 hours after Forteo administration was increased from 2% of women and none of the men treated with placebo to 11% of women and 6% of men treated with Forteo.
  • The number of patients treated with Forteo whose transient hypercalcemia was verified on consecutive measurements was 3% of women and 1% of men.
Urinary Calcium
  • Forteo increased urinary calcium excretion, but the frequency of hypercalciuria in clinical trials was similar for patients treated with Forteo and placebo.
Serum Uric Acid
  • Forteo increased serum uric acid concentrations. In clinical trials, 3% of Forteo patients had serum uric acid concentrations above the upper limit of normal compared with 1% of placebo patients.
  • However, the hyperuricemia did not result in an increase in gout, arthralgia, or urolithiasis.
Renal Function
  • No clinically important adverse renal effects were observed in clinical studies.
  • Assessments included creatinine clearance; measurements of blood urea nitrogen (BUN), creatinine, and electrolytes in serum; urine specific gravity and pH; and examination of urine sediment.

Studies In Men And Women With Glucocorticoid-Induced Osteoporosis

The safety of Forteo in the treatment of men and women with glucocorticoid-induced osteoporosis was assessed in a randomized, double-blind, active-controlled trial of 428 patients (19% men, 81% women) aged 22 to 89 years (mean 57 years) treated with ≥ 5mg per day prednisone or equivalent for a minimum of 3 months.

The duration of the trial was 18 months with 214 patients exposed to Forteo and 214 patients exposed to oral daily bisphosphonate (active control). All patients received 1000 mg of calcium plus 800 IU of vitamin D supplementation per day.

The incidence of all cause mortality was 4% in the Forteo group and 6% in the active control group. The incidence of serious adverse events was 21% in Forteo patients and 18% in active control patients, and included pneumonia (3% Forteo, 1% active control). Early discontinuation because of adverse events occurred in 15% of Forteo patients and 12% of active control patients, and included dizziness (2% Forteo, 0% active control).

Adverse events reported at a higher incidence in the Forteo group and with at least a 2% difference in Forteo-treated patients compared with active control-treated patients were:

Postmarketing Experience

The following adverse reactions have been identified during postapproval use of Forteo. 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.

  • Osteosarcoma: Cases of bone tumor and osteosarcoma have been reported rarely in the postmarketing period. The causality to Forteo use is unclear. Long term osteosarcoma surveillance studies are ongoing
  • Hypercalcemia: Hypercalcemia greater than 13.0 mg/dL has been reported with Forteo use.

Adverse events reported since market introduction that were temporally (but not necessarily causally) related to Forteo therapy include the following:

  • Allergic Reactions: Anaphylactic reactions, drug hypersensitivity, angioedema, urticaria
  • Investigations: Hyperuricemia
  • Respiratory System: Acute dyspnea, chest pain
  • Musculoskeletal: Muscle spasms of the leg or back
  • Other: Injection site reactions including injection site pain, swelling and bruising; oro-facial edema

What drugs interact with Forteo (teriparatide)?

Digoxin

  • A single Forteo dose did not alter the effect of digoxin on the systolic time interval (from electrocardiographic Q-wave onset to aortic valve closure, a measure of digoxin's calcium-mediated cardiac effect).
  • However, because Forteo may transiently increase serum calcium, Forteo should be used with caution in patients taking digoxin.

Hydrochlorothiazide

  • The coadministration of hydrochlorothiazide 25 mg with teriparatide did not affect the serum calcium response to teriparatide 40 mcg.
  • The effect of coadministration of a higher dose of hydrochlorothiazide with teriparatide on serum calcium levels has not been studied.

Furosemide

  • Coadministration of intravenous furosemide (20 to 100 mg) with teriparatide 40 mcg in healthy people and patients with mild, moderate, or severe renal impairment (CrCl 13 to 72 mL/min) resulted in small increases in the serum calcium (2%) and 24-hour urine calcium (37%) responses to teriparatide that did not appear to be clinically important.

Summary

Forteo (teriparatide) is a man-made form of parathyroid hormone used to treat osteoporosis, a bone disease that over time causes bones to become fragile and more likely to break. Common side effects of Forteo include nausea, joint aches, and pain. There are no available data on Forteo use in pregnant women to evaluate for drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes. It is unknown if Forteo is excreted in breast milk, affects milk production, or has effects on a breastfed infant.

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Medically Reviewed on 11/17/2020
References
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Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.