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Frequently asked questions about Strensiq® (asfotase alfa)

Below are the questions we hear the most from people who are new to Strensiq. If you don't see what you’re looking for, call OneSource™ Treatment Support at
1-888-765-4747 to speak with an Alexion nurse case manager.

Strensiq is a prescription medicine that is indicated for the treatment of patients with perinatal/infantile- and juvenile-onset hypophosphatasia. People with hypophosphatasia have low levels of alkaline phosphatase.

People with hypophosphatasia have low levels of alkaline phosphatase. Strensiq replaces the alkaline phosphatase enzyme. When alkaline phosphatase is replaced with Strensiq, phosphate and calcium are able to bond together and improve bone health.

Strensiq is given as an injection under the skin (called a subcutaneous injection). Depending on a person's age and ability, Strensiq can be self-injected or injected by a caregiver.

Your doctor will prescribe a specific dose of Strensiq based on your weight or your child's weight and will decide how often it should be given. If there are any significant changes in weight, your doctor will adjust the dose. If you miss a dose of Strensiq, contact your doctor for advice. It is important to use Strensiq as described in the Patient Prescribing Information and Instructions for Use, and as instructed by your doctor, nurse, or pharmacist.

Strensiq does not need to be taken at a specific time, but it is important to inject Strensiq around the same time each day. Find a time that works for you and your family. Some people find taking Strensiq right after they wake up helps it become part of their daily routine, while others prefer to take Strensiq in the evening before bed.

Strensiq can cause side effects. The most common side effects of Strensiq include local skin injection-site reactions (including red skin patches, bruising, color change, pain, itching, thinning, swelling, pits, and bumps) and calcium buildup in your eyes and kidneys.

Rotating the area on the body where you inject Strensiq can help avoid irritation and reactions at the injection site. Talk to your doctor about other ways to help manage these reactions.

Please see the Important Safety Information for a complete list of possible side effects of Strensiq.

Strensiq should be refrigerated in its original package at 36°F to 46°F (2° to 8°C). Since medications should be kept out of the reach of children, OneSource™ can provide access to a specialized medication refrigerator to help store Strensiq and track injections. Call OneSource™ at 1-888-765-4747 for more information.

When traveling with Strensiq, make sure to keep your Strensiq refrigerated throughout your trip. Before traveling, gather your injection supplies and check with your destination to make sure there will be a place to refrigerate Strensiq when you get there. If you are planning a trip, call OneSource™ at 1-888-765-4747 to learn more about traveling with Strensiq.

OneSource™ is staffed by Alexion nurse case managers who are registered nurses with healthcare and insurance experience. After enrolling, you'll be matched with a nurse case manager who can answer questions about hypophosphatasia and treatment with Strensiq, send you useful educational tools and resources, provide treatment support, and connect you with others living with hypophosphatasia.

Call your Alexion nurse case manager at 1-888-765-4747 for information regarding financial assistance, co-pay programs, and the Alexion Access Foundation, which can provide useful information about treatment to people without access to insurance. Alexion nurse case managers can assist with insurance issues and help you find solutions to maintain continuous care. Some people may not be eligible for certain services.



Strensiq is a prescription medicine used to treat people with perinatal/infantile- and juvenile-onset hypophosphatasia (HPP).

What are the possible side effects of STRENSIQ?
STRENSIQ may cause serious side effects, including
  • Serious allergic (hypersensitivity) reactions happened in some people who use STRENSIQ. Stop using STRENSIQ and go to the nearest hospital emergency room right away if you or your loved one have any of the signs and symptoms of a serious allergic reaction, including
    • Difficulty breathing
    • Swelling of your eyes, lips, or tongue
    • Hives
    • Feeling faint
    • Nausea or vomiting
    • Dizziness
    • Itching of your lips, tongue, or throat
    • Choking sensation
  • Skin thickening or pits at the injection site (lipodystrophy) has happened several months after using STRENSIQ.
  • Calcium buildup in the eyes and kidneys can occur if you or your loved one have HPP. Your healthcare provider should check the eyes and kidneys while you or your loved one use STRENSIQ.
  • Decreased efficacy. Contact your healthcare provider if you or your loved one notice STRENSIQ is no longer working or experience worsening symptoms of HPP (e.g., increased respiratory support, increased difficulty walking, new fractures).
The most common side effects of STRENSIQ include local skin injection-site reactions (including red skin patches, bruising, color change, pain, itching, thinning, swelling, pits, and bumps) and calcium buildup in your eyes and kidneys.

Strensiq may affect other lab test results, therefore it is important that you present your Medical Alert Card to your healthcare team so they are aware that you are being treated with an alkaline phosphatase (ALP) replacement therapy which may cause incorrect results on certain laboratory tests.

 Tell your doctor if you are pregnant or plan to become pregnant, or are breastfeeding or plan to breastfeed.

These are not all the possible side effects of STRENSIQ. For more information, ask your healthcare provider or pharmacist. Call your healthcare provider for medical advice about side effects. You may report side effects to the US Food and Drug Administration at 1-800-FDA-1088.

Please see STRENSIQ full Prescribing Information, including Patient Information and Instructions for Use.