Forteo

Primary Uses

Forteo is used to treat bone loss and reduce the risk of fractures in specific groups of people. Unlike many other osteoporosis medications that work by slowing down bone loss, this medication helps the body build new bone to increase bone density. It is specifically approved for the following groups:

• Postmenopausal women: For women with osteoporosis who are at high risk for fractures or who have not responded well to other osteoporosis treatments.
• Men with osteoporosis: To increase bone mass in men with primary or hypogonadal osteoporosis who are at high risk for fractures.
• Steroid-induced osteoporosis: For men and women who are at high risk for fractures due to long-term use of systemic glucocorticoid medications, such as prednisone.

When It Is Prescribed

Healthcare providers typically prescribe Forteo for patients who meet certain clinical criteria, including:

• A history of osteoporotic fractures.
• Multiple risk factors for bone fractures.
• Intolerance to other types of osteoporosis treatments.
• Failure of other osteoporosis therapies to increase bone mass or prevent fractures.

Because of its specific mechanism, Forteo is often reserved for those with more severe bone loss or those who require a treatment that actively builds new bone rather than just slowing bone loss.

Mechanism of Action

Forteo contains teriparatide, which is a man-made form of parathyroid hormone. This hormone is naturally produced by the parathyroid glands in the body to regulate calcium and phosphate levels in the blood and bones.

Building New Bone

Most osteoporosis medications work by slowing down the process of bone loss. Forteo works differently because it is an anabolic agent, meaning it actively stimulates the formation of new bone. It achieves this by:

• Stimulating bone-forming cells: It increases the activity of osteoblasts, which are the cells responsible for building new bone tissue.
• Improving bone structure: By increasing the number and activity of these cells, the medication helps to thicken existing bone and improve the overall architecture of the skeleton.
• Increasing bone mineral density: Regular use leads to higher bone mass, particularly in the spine and hips.

While the body naturally breaks down and replaces bone tissue constantly, Forteo shifts this balance so that more bone is created than is removed. By building new, stronger bone, the medication helps to reduce the risk of fractures in people with certain types of osteoporosis.

Common Side Effects

The most frequently reported side effects of Forteo are generally mild and may include:

• Nausea
• Joint pain
• Leg cramps
• Dizziness
• Headache
• Runny nose or cough
• Injection site reactions, such as redness, swelling, or bruising

Serious Side Effects

Some individuals may experience more severe reactions that require medical evaluation:

• High Blood Calcium (Hypercalcemia): This condition can cause symptoms such as nausea, vomiting, constipation, lack of energy, or muscle weakness.
• Dizziness upon Standing: Some people feel faint or dizzy shortly after an injection. This usually happens within the first few doses and typically goes away within a few hours.
• Kidney Stones: Forteo can increase calcium in the urine, which may lead to kidney stones. Symptoms include sharp pain in the lower back or side, or blood in the urine.
• Fast Heartbeat: You may feel like your heart is racing or pounding.

If you experience severe bone pain or persistent symptoms, consult your doctor to evaluate your treatment plan.

Bone Cancer Risk

In animal studies, teriparatide caused an increase in the incidence of osteosarcoma, a rare but serious bone cancer. While the risk in humans is not fully established, the medication is generally avoided in patients who have a higher baseline risk for bone cancer, including:

• Patients with Paget's disease of the bone.
• Children and young adults with open growth plates (epiphyses).
• People who have had radiation therapy involving the skeleton.
• Patients with unexplained elevations of alkaline phosphatase.
• Patients with hereditary disorders predisposing them to bone cancer.

Orthostatic Hypotension

Some patients experience a sudden drop in blood pressure when sitting up or standing shortly after an injection. This may cause dizziness, palpitations, or fainting. These symptoms typically occur within four hours of the dose and usually resolve within a few hours. It is often recommended to administer the injection in a setting where the patient can sit or lie down if needed.

Calcium and Kidney Stones

Forteo can increase the amount of calcium in the blood and urine. It should be used with caution in patients with active or recent kidney stones or those with conditions that cause high calcium levels (hypercalcemia). Healthcare providers may monitor blood and urine calcium levels during treatment.

Treatment Duration

The safety and efficacy of using teriparatide for more than two years during a patient's lifetime have not been well-studied. Consequently, the total lifetime duration of treatment with Forteo is generally limited to 24 months.

Pregnancy

There are no adequate or well-controlled studies of Forteo in pregnant women. Research in animals has shown that the drug may cause harm to a developing fetus. Because Forteo is primarily used to treat osteoporosis in postmenopausal women and in men, it is not commonly prescribed to people of childbearing age.

If you are pregnant or planning to become pregnant, talk with a healthcare provider about the potential risks. The medication is typically only used during pregnancy if the clinical need is clear and the potential benefits justify the risks to the fetus.

Breastfeeding

It is not known if Forteo is excreted in human breast milk. Because of the potential for serious adverse reactions in a nursing infant, a decision must be made whether to stop breastfeeding or stop taking the medication. Patients should discuss these options with their healthcare team to ensure the safety of the infant while managing their own health condition.

Available Forms

Forteo is provided as a prefilled delivery device, commonly referred to as a pen. This device contains a sterile, colorless solution intended for subcutaneous injection (under the skin).

Strengths

The medication is available in a single strength and delivery format:

• Prefilled Pen: Each pen contains enough medication for 28 daily doses. The device is designed to deliver a fixed dose of 20 micrograms of teriparatide per injection.

The pen must be used with compatible disposable needles, which are typically prescribed separately. Each pen is intended for use by a single patient and should be stored in a refrigerator between uses.

FDA Approval and Indications

The U.S. Food and Drug Administration (FDA) has approved Forteo (teriparatide) for the treatment of osteoporosis in specific populations who have a high risk of bone fractures or who have failed other treatments. Approved indications include:

• Postmenopausal women with osteoporosis.
• Men with primary or hypogonadal osteoporosis.
• Men and women with osteoporosis associated with sustained systemic glucocorticoid therapy (such as prednisone).

Regulatory History and Safety Warnings

Forteo previously carried a boxed warning regarding a potential risk of osteosarcoma, a type of bone cancer, based on findings in animal studies. In late 2020, the FDA removed this boxed warning after reviewing long-term safety data that suggested the risk in humans was lower than initially observed in laboratory settings. Despite the removal of the boxed warning, the medication still includes warnings for patients with an increased baseline risk for osteosarcoma, such as those with Paget's disease of the bone, open epiphyses (pediatric patients), or prior radiation therapy involving the skeleton.

Usage Limitations

Due to the potential risks identified in early clinical studies, the FDA-approved labeling specifies that the total lifetime use of teriparatide products should generally be limited to a maximum of two years. This cumulative limit applies to Forteo and any other teriparatide-based medications a patient may receive over their lifetime.

Factors Affecting Price

The total price of Forteo can vary based on the following:

• Insurance Coverage: Most insurance plans, including Medicare Part D, cover Forteo, but it is often placed on a higher specialty tier. This may result in a higher copayment or coinsurance amount. Prior authorization is typically required before the insurance company will cover the medication.
• Generic Availability: Teriparatide, the active ingredient in Forteo, is available as a generic or biosimilar. Generic versions are usually significantly less expensive than the brand-name drug.
• Pharmacy Type: Because Forteo is an injectable medication that requires refrigeration, it is often dispensed through specialty pharmacies rather than standard retail pharmacies.

Additional Costs

Patients should also account for the cost of pen needles, which are required for the injection but are usually sold separately from the prefilled pen. Additionally, because the medication must be kept cold, patients may need to purchase insulated travel kits if they frequently transport the medication.

Financial Assistance Programs

The manufacturer may offer savings cards or copay assistance for patients with commercial insurance. For those without insurance or with limited financial resources, patient assistance programs may be available to help provide the medication at a lower cost or for free. Eligibility for these programs is usually based on income and insurance status.