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Strensiq Side Effects

Generic name: asfotase alfa

Medically reviewed by Drugs.com. Last updated on Feb 28, 2025.

Note: This document provides detailed information about Strensiq Side Effects associated with asfotase alfa. Some dosage forms listed on this page may not apply specifically to the brand name Strensiq.

Applies to asfotase alfa: subcutaneous solution.

Serious side effects of Strensiq

Along with its needed effects, asfotase alfa (the active ingredient contained in Strensiq) 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 while taking asfotase alfa:

More common side effects

  • 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

Rare side effects

  • 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

Other side effects of Strensiq

Some side effects of asfotase alfa 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 side effects

  • 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

Managing side effects (general information)

For healthcare professionals

Applies to asfotase alfa: subcutaneous solution.

General adverse events

The most common adverse reactions include injection site reactions, lipodystrophy, ectopic calcifications, and hypersensitivity reactions.[Ref]

Hypersensitivity

In clinical trials 1 treated-patient (n=99; 1%) experienced signs and symptoms consistent with anaphylaxis. This patient had been receiving this drug for 3.5 years before this reaction occurred. The reaction (difficulty breathing, nausea, periorbital edema, and dizziness) occurred approximately 1 minute after injection and resolved without medical treatment. This patient continued on therapy with premedication and eventually continued treatment without premedication.

Hypersensitivity reactions including nausea/vomiting, fever, headache, flushing, irritability, rigor/chills, skin erythema, rash, pruritus, and oral hypoesthesia have been reported.[Ref]

Local

Localized lipodystrophy, including lipoatrophy and lipohypertrophy, has been reported after several months. The frequency of injection site reactions and lipodystrophy were higher in patients with juvenile-onset hypophosphatasia (HPP) as compared to perinatal/infantile onset HPP patients.

Injection site reactions included erythema, discoloration/hyperpigmentation, pain/tenderness, pruritus/itching, swelling, induration, macule, bruising, nodule, injection site rash, inflammation, papules, hemorrhage, hematoma, urticaria, warmth, calcification, mass, scar, and cellulitis. The majority of injection site reactions resolved within 1 week. One patient experienced a severe injection site reaction of injection site discoloration and withdrew from the clinical trial.[Ref]

Renal

In clinical trials, there were 14 cases (14%) of ectopic calcification of the eye (including the cornea and conjunctiva) and the kidneys (nephrocalcinosis). No visual changes or changes in renal function were reported as a result of these ectopic calcifications. The frequency of ectopic calcifications was higher in patients with juvenile-onset hypophosphatasia (HPP) as compared to perinatal/infantile onset HPP patients.

Renal stones have been reported in less than 1% of patients.[Ref]

Ocular

In clinical trials, there were 14 cases (14%) of ectopic calcification of the eye (including the cornea and conjunctiva) and the kidneys (nephrocalcinosis). No visual changes or changes in renal function were reported as a result of these ectopic calcifications. The frequency of ectopic calcifications was higher in patients with juvenile-onset hypophosphatasia (HPP) as compared to perinatal/infantile onset HPP patients.[Ref]

Hepatic

Chronic hepatitis has been reported in less than 1% of patients.

Immunologic

In clinical trials, 78% (76/98) of patients tested positive for anti-drug antibodies at some point after receiving treatment. Of these patients, 45% (34/76) had neutralizing antibodies. No correlation was observed between anti-drug antibody titer and neutralizing antibody (% inhibition) values. Formation of anti-drug antibody resulted in a reduced systemic exposure.

Metabolic

Hypocalcemia and decreased vitamin B6 have been reported in less than 1% of patients

References

1. Cerner Multum, Inc. "UK Summary of Product Characteristics."

2. (2015) "Product Information. Strensiq (asfotase alfa)." Alexion Pharmaceuticals Inc

Further information

Strensiq side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

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