FAQs About Natpara for Hypoparathyroidism
Natpara is the only approved treatment for patients with hypoparathyroidism.
A U.S. recall related to problems with its packaging, which came in effect in September 2019, has led to continuing difficulties in obtaining the medication in the country.
Natpara is marketed by Takeda Pharmaceuticals, and was developed by Shire, now part of Takeda.
How does Natpara work?
Hypoparathyroidism results from low levels of parathyroid hormone (PTH), produced in the four parathyroid glands of the neck. PTH deficiency leads to low blood levels of calcium ions (hypocalcemia) and high blood levels of phosphorus. The imbalance of these two elements causes the symptoms of hypoparathyroidism.
Natpara is a hormone replacement therapy. It is a solution containing PTH that you inject under the skin to help replace the missing PTH and restore adequate calcium levels.
How can I get it?
Takeda issued a U.S. recall for Natpara in September 2019 due to issues with its packaging that raised a risk of rubber fragments breaking from its capsule. The company set up a special use program (SUP) for patients using the treatment and facing life-threatening complications due to Natpara’s inavailability. Only a limited number of people, however, qualify for this program.
The European Medicines Agency (EMA) chose not to recall Natpar (Natpara’s brand name in Europe) for patients in EU countries.
Takeda announced a need for more modifications and testing in addressing capsule problems than initially anticipated in January 2020, affecting its timeline for reintroducing Natpara to U.S. patients. A restoration of treatment availability was reported to be pushed back at least to March 2021.
In a potential setback, Takeda also announced a possible supply interruption for SUP patients in the U.S. using its 100 mcg dose in October 2020. The interruption could begin the following month, as early as Nov. 21, the company said, attributing it to a separate issue from that which led to the recall.
Patients in the SUP program using that daily dose and their doctors were to be contacted by representatives with the company’s OnePath program, offering more information and recommendations for treatment options should availability of this Natpara dose be affected.
What is OnePath?
OnePath is Takeda’s patient support program. It is designed to help you navigate insurance, provide information on potential financial support for treatment, aid you in getting your prescriptions, and help to train you in preparing and injecting your treatment.
Why was there a U.S. recall?
The recall was due to issues with the Natpara cartridge packaging. The cartridge, which is used for 14 days, has a rubber stopper that is punctured by a needle each day in order to deliver the necessary dose of medication. Repeated puncturing of the rubber stopper can lead to small rubber particles being released into the solution, potentially clogging the needle and leading to patients getting an insufficient dose.
What alternatives are available?
If you were taking Natpara, the Endocrine Society and the American Society for Bone Mineral Research (ASBMR) recommends transitioning either to the previous standard hypoparathyroidism treatment of oral calcium and calcitriol (activated vitamin D), or moving to off-label use of teriparatide. The U.S. Food and Drug Administration (FDA) has not approve teriparatide to treat hypoparathyroidism. It is an FDA-approved treatment for osteoporosis, sold under the brand name Forteo.
How do I take Natpara?
Natpara is injected under the skin of the thigh once daily, using an alternate thigh each day. It comes in four dosage strengths: 25 mcg, 50, mcg, 75 mcg, and 100 mcg. Most patients start with a 50 mcg dose, and your doctor will adjust your dose as necessary to ensure you achieve a calcium level that reaches at least the lower range of normal.
When your doctor prescribes this medication, a nurse will guide you in learning how to prepare and inject the treatment. Your doctor may also have you adjust your daily intake of calcium and vitamin D.
How often should I take Natpara?
You should inject Natpara once a day into the skin of your thigh. You should alternate which thigh you inject each day.
What are potential side effects?
Natpara has a potential to cause serious side effects. The most serious risk of taking the medication is that of osteosarcoma, a form of bone cancer.
Natpara can also cause hypercalcemia (high levels of calcium in the blood), which can lead to kidney stones and interfere with the function of your brain and heart. Hypercalcemia can also cause nausea or vomiting, drops in energy, constipation, and muscle weakness.
Missing doses of Natpara can result in severe hypocalcemia, with calcium levels dropping lower than usual. Signs of hypocalcemia can include tingling sensations, muscle cramping, depression, seizures, and problems with memory or thinking.
A risk of a reaction to the treatment is also possible, including a severe allergic reaction known as anaphylaxis. You should notify your doctor immediately if you develop swelling, itching, a rash, hives, breathing problems, or episodes of fainting or dizziness with its use.
Are there reasons I shouldn’t take Natpara?
You should not take Natpara if you are allergic to PTH or other substances in the medication. You should also tell your doctor if you are using digoxin, as hypercalcemia may lead to digoxin toxicity.
How should I store Natpara?
You should store both unmixed and prepared cartridges of Natpara in the refrigerator, with temperatures set between 36 F to 46 F (2 C to 8 C). It is important that you do not freeze or shake the solution.
You should not store or use mixed cartridges for more than 14 days.
Last updated: Oct. 30, 2020
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