What is Teriparatide used for?

Teriparatide, a recombinant form of parathyroid hormone, has revolutionized the treatment landscape for osteoporosis. Sold under trade names such as Forteo and Forsteo, it is primarily indicated for individuals who are at high risk of fractures. The drug is particularly beneficial for postmenopausal women and men with primary or hypogonadal osteoporosis, as well as individuals with osteoporosis associated with prolonged systemic glucocorticoid therapy. Developed and researched by pharmaceutical companies like Eli Lilly and approved by the FDA in 2002, teriparatide remains a cornerstone in osteoporosis treatment protocols.

Teriparatide works by stimulating bone formation. Unlike other osteoporosis medications that mainly prevent bone resorption, teriparatide promotes the building of new bone, making it unique among osteoporosis treatments. This mechanism involves the activation of osteoblasts, the cells responsible for bone formation. By binding to specific receptors on osteoblasts, teriparatide promotes these cells' proliferation and activity, leading to increased bone mass and improved bone architecture. This anabolic effect is vital for patients at high risk of fractures as it not only increases bone density but also enhances bone quality.

The administration of teriparatide is relatively straightforward but requires patient education and compliance. It is given as a daily subcutaneous injection, typically in the thigh or abdomen. The recommended dosage is 20 micrograms per day, and the drug comes in a prefilled pen-like device for ease of use. Patients are usually advised to administer the injection around the same time each day to maintain consistent blood levels of the medication. The onset of action can be observed within a few weeks of initiating treatment, with significant improvements in bone mineral density typically noticeable within 18 to 24 months. However, it is essential to note that the use of teriparatide is generally limited to a maximum of two years due to the risk of osteosarcoma observed in animal studies.

Like all medications, teriparatide comes with its own set of potential side effects and contraindications. Common side effects include nausea, leg cramps, and dizziness. Some patients may also experience pain or redness at the injection site. More severe side effects, although rare, can include hypercalcemia, which is an elevated level of calcium in the blood, and orthostatic hypotension, which is a drop in blood pressure upon standing. Due to the potential risk of osteosarcoma, teriparatide is contraindicated in individuals with pre-existing hypercalcemia, bone metastases or skeletal malignancies, and those with a history of radiation therapy involving the skeleton. Patients with Paget's disease of bone, a condition characterized by abnormal bone destruction and regrowth, should also avoid using teriparatide. Regular monitoring of calcium levels and bone markers is recommended during treatment to mitigate these risks.

Drug interactions are an important consideration when prescribing teriparatide. Certain medications can affect how teriparatide works or increase the risk of side effects. For instance, digoxin, a drug used to treat heart conditions, can have its effects potentiated by teriparatide, increasing the risk of digoxin toxicity. It is crucial to monitor patients closely if they are on both medications. Additionally, the concurrent use of bisphosphonates, another class of osteoporosis drugs that work by inhibiting bone resorption, may blunt the anabolic effects of teriparatide. Therefore, it is generally recommended to avoid using these two classes of drugs together. Other medications that may interact with teriparatide include diuretics, which can alter calcium levels and potentially exacerbate hypercalcemia when used alongside teriparatide.

In conclusion, teriparatide is a powerful medication offering hope for patients with severe osteoporosis and a high risk of fractures. Its ability to stimulate new bone formation sets it apart from other osteoporosis treatments. However, its use requires careful patient selection, education, and monitoring to maximize benefits and minimize risks. Understanding the drug's mechanism of action, proper administration techniques, potential side effects, contraindications, and drug interactions is essential for healthcare providers and patients alike to ensure the safe and effective use of teriparatide.