Asfotase alfa

Asfotase alfa is a prescription medication used to treat hypophosphatasia, a rare inherited, metabolic disease that affects the development of bones and teeth.

Asfotase alfa works by replacing the enzyme (known as tissue-nonspecific alkaline phosphatase) responsible for formation of an essential mineral in normal bone. 

This medication is available as an injection to be given under the skin. It is typically injected three or six times per week by a healthcare professional. 

Common side effects of asfotase alfa include injection site reactions and severe allergic reactions such as difficulty breathing, nausea, dizziness and fever. 

Asfotase alfa is a prescription medication used to treat hypophosphatasia, a rare inherited, metabolic disease that has started in childhood. Hypophosphatasia affects the development of bones and teeth. 

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Asfotase alfa may be found in some form under the following brand names:

• Strensiq

Serious side effects have been reported with asfotase alfa. See the “Asfotase alfa Precautions” section.

Common side effects of asfotase alfa include the following:

• injection site reactions
• severe allergic (hypersensitivity) reactions (such as difficulty breathing, nausea, dizziness and fever)
• lipodystrophy (a loss of fat tissue resulting in an indentation in the skin or a thickening of fat tissue resulting in a lump under the skin) at the injection site
• ectopic calcifications of the eyes and kidney

This is not a complete list of asfotase alfa side effects. Ask your doctor or pharmacist for more information.

Tell your doctor if you have any side effect that bothers you or that does not go away.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

No drug interactions for asfotase alfa have been evaluated by the manufacturer. However, you should tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Not all drug interactions are known or reported and new drug interactions are continually being reported.

Serious side effects have been reported with asfotase alfa including the following:

• Hypersensitivity (severe allergic reaction). Tell your healthcare provider about any signs or symptoms of hypersensitivity, which include the following:

  • chest pain
  • swelling of the face, eyes, lips, tongue, arms, or legs
  • difficulty breathing or swallowing
  • rash
  • nausea or vomiting
  • fever
  • itching of the lips, tongue, or throat
• Lipodystrophy (a loss of fat tissue resulting in an indentation in the skin or a thickening of fat tissue resulting in a lump under the skin) at the site where asfotase alfa is injected
• Ectopic calcifications (calcium buildup in your eyes and kidneys). Your doctor may recommend eye exams and imaging of your kidneys while you are on asfotase alfa.

Do not take asfotase alfa if you are allergic to asfotase alfa or any of its ingredients.

Medications can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of asfotase alfa, there are no specific foods that you must exclude from your diet when receiving this medication.

Before taking asfotase alfa, tell your doctor about all of your medical conditions. Especially tell your doctor if you:

• are allergic to asfotase alfa or any of its ingredients
• are pregnant or planning to become pregnant
• are breastfeeding or planning to breastfeed

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

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

There are no studies that have been done in humans with asfotase alfa. In animal studies, pregnant animals were given this medication, and the babies did not show any medical issues related to this medication.

It is not known if asfotase alfa crosses into human milk. Because many medications can cross into human milk and because of the possibility for serious adverse reactions in nursing infants with use of this medication, a choice should be made whether to stop nursing or stop the use of this medication. Your doctor and you will decide if the benefits outweigh the risk of using asfotase alfa.

Use asfotase alfa exactly as prescribed.

Asfotase alfa comes as an injection to be given under the skin. It is typically injected three or six times per week.

Your healthcare provider will tell you how much asfotase alfa to use and when to use it.

Your healthcare provider may change your dose if needed.

Change (rotate) your injection site with each injection. Do not use the same injection site for each injection.

To inject asfotase alfa, follow these instructions:

1. Wash your hands.
2. Check the liquid in the vial of asfotase alfa. Do not use if it is discolored or contains large particles in it.
3. Pull back the plunger on your syringe until the black tip reaches the line for your prescribed dose.
4. Push the needle through the rubber stopper into the vial.
5. Turn the vial and syringe upside down and push the plunger all the way in, inserting air into the vial.
6. Slowly pull the plunger back to the line slightly beyond the correct dose that you need.
7. With the needle still in the vial, slowly push the plunger up until the top of it reaches the line for your prescribed dose.
8. Pull the syringe out of the vial. If there are air bubbles, tap the syringe gently with your finger to remove them.
9. Clean your injection site with an alcohol wipe and let dry.
10. Inject asfotase alfa in your stomach area, upper arms, or upper legs as directed by your doctor. Do not inject if your skin is red or swollen.

If the volume to be injected is more than 1 mL, it will need to be split into two syringes and injected into two different injection sites. Make sure that you rotate the sites where you are injecting asfotase alfa.

If you miss a dose, take the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed dose and take your next dose at the regular time. Do not take two doses of asfotase alfa at the same time.

Take this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The dose your doctor recommends may be based on your weight and how you respond to asfotase alfa.

The recommended dose of Strensiq (asfotase alfa) for hypophosphatasia is 6 mg per kilogram of body weight per week, given subcutaneously (under the skin) as either three or six injections per week. Your doctor may adjust your dose based on your response up to the maximum dose of 9 mg per kilogram of body weight per week.

If you take too much asfotase alfa, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

If asfotase alfa is administered by a healthcare provider in a medical setting, it is unlikely that an overdose will occur. However, if overdose is suspected, seek emergency medical attention.

• Store asfotase alfa in the original carton in the refrigerator.
• Keep asfotase alfa vials away from light until you are about to use it.
• Use asfotase alfa within one hour of removing it from the refrigerator.
• Do not freeze or shake asfotase alfa vials.
• Asfotase alfa vials are single-use vials; throw away any unused product.