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Asfotase alfa (Subcutaneous)

Generic name: asfotase alfa [ AS-foe-tase-AL-fa ]
Drug class: Miscellaneous metabolic agents

Medically reviewed by Last updated on Oct 23, 2022.

Uses for asfotase alfa

Asfotase alfa injection is used to treat patients with perinatal, infantile, and juvenile-onset hypophosphatasia (HPP). Hypophosphatasia is a genetic condition that weakens and softens the bones, causing abnormal development of the bones and teeth.

This medicine is available only with your doctor's prescription.

Before using asfotase alfa

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of asfotase alfa injection in the pediatric population. Safety and efficacy have been established.


No information is available on the relationship of age to the effects of asfotase alfa injection in geriatric patients.

Breast Feeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with Medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Eye or vision problems or
  • Kidney disease—Use with caution. May make these conditions worse.

Proper use of asfotase alfa

A nurse or other trained health professional may give you this medicine. It is given as a shot under the skin of your upper arm, buttock, stomach, or thigh. Do not inject this medicine into the buttocks for infants.

You may be taught how to give this medicine at home. Make sure you understand all of the instructions before giving yourself or your child an injection. Do not use more medicine or use it more often than your doctor tells you to.

This medicine comes with a patient information leaflet and patient instructions. Read and follow these instructions carefully. Ask your doctor if you have any questions about:

  • How to prepare the injection.
  • The proper use of disposable syringes.
  • How to give the injection.
  • How long the injection can be stored at home.

Allow this medicine to warm to room temperature for at least 15 to 30 minutes before you use it. Do not warm it in any other way.

Check the liquid in the vial. It should be clear or slightly yellow and may have a few small white particles in it. Do not use the medicine if the liquid is discolored or has lumps or large particles in it. Do not shake the vial.

Use the vial only once. Do not save leftover medicine.


The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For injectable dosage form (solution):
    • For perinatal, infantile, and juvenile-onset hypophosphatasia:
      • Children weighing 3 to 80 kilograms (kg)—Dose is based on body weight and must be determined by your doctor. The dose is usually 6 milligrams (mg) per kg (mg/kg) per week (given either as 2 mg/kg three times a week or 1 mg/kg six times a week) given as a shot under the skin.
      • Children weighing less than 3 kg—Use and dose must be determined by your doctor.

Missed Dose

This medicine needs to be given on a fixed schedule. If you miss a dose or forget to use your medicine, call your doctor or pharmacist for instructions.


Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Store in the refrigerator. Do not freeze.

Use the vial within 3 hoursafter removing it from the refrigerator. Throw away any unused medicine.

Throw away used needles in a hard, closed container where the needles cannot poke through. Keep this container away from children and pets.

Precautions while using asfotase alfa

It is very important that your doctor check you or your child's progress at regular visits to make sure that this medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.

This medicine may cause serious allergic reactions, including anaphylaxis, which can be life-threatening and requires immediate medical attention. Tell your doctor right away if you or your child have a rash, itching, hoarseness, trouble breathing, trouble swallowing, or any swelling of the hands, face, or mouth after using this medicine.

This medicine may cause redistribution of body fat or thickening, depression, or indentation of the skin at the injection site after several months of using it. Make sure to follow the instructions on the proper way of injecting the medicine and to rotate the injection sites regularly. Use 2 separate injection sites when giving 2 doses of this medicine.

This medicine may cause calcium to build-up in the eyes or kidneys, which could lead to more serious unwanted effects. Check with your doctor right away if you or you child have redness or dryness of the eye, difficult or painful urination, bloody urine, nausea, vomiting, pain in the groin or genitals, sharp back pain just below the ribs, or if you or your child see floating dark spots or material before the eyes.

Asfotase alfa may possibly cause the body to develop antibodies against it, which can lessen the effects of this medicine. If your or your child's symptoms do not improve within a few days, or if they become worse, check with your doctor.

Make sure any doctor or dentist who treats you knows that you are using this medicine. This medicine may affect the results of certain medical tests.

Side Effects of asfotase alfa

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

  • Bloody urine
  • chest tightness
  • depression, indentation, or thickening of the skin at the injection site
  • difficult or painful urination
  • dryness or redness of the eye
  • fast heartbeat
  • fever
  • hives, itching, skin rash
  • hoarseness
  • irritation
  • joint pain, stiffness, or swelling
  • nausea
  • pain in the groin or genitals
  • redistribution or accumulation of body fat
  • redness of the skin
  • seeing floating dark spots or material before the eyes
  • sharp back pain just below the ribs
  • swelling of the eyelids, face, lips, hands, or feet
  • trouble breathing or swallowing
  • vomiting


  • Chills
  • clay-colored stools
  • confusion
  • dark urine
  • diarrhea
  • dizziness
  • fever
  • headache
  • irregular heartbeat
  • loss of appetite
  • mood or mental changes
  • muscle cramps in the hands, arms, feet, legs, or face
  • numbness and tingling around the mouth, fingertips, or feet
  • seizures
  • stomach cramps or pain
  • tremor
  • unpleasant breath odor
  • unusual tiredness or weakness
  • vomiting of blood
  • yellow eyes or skin

Incidence not known

  • Increased troubled breathing
  • increased difficulty walking
  • new pain or swelling in the arms or legs without any injury

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

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

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.