Important Nursing Guide: Correct Reconstitution and Injection Technique for Asfotase Alfa

Asfotase alfa (Strensiq) is an enzyme replacement therapy used to treat hypophosphatasia. Proper reconstitution and injection are essential to ensure the full dose is delivered safely and effectively. This guide walks you through step by step, using clear language and evidence-based best practices. If at any point you’re concerned about severe symptoms—or if you need more personalized advice—please speak to a doctor. You might also consider a free, online symptom check, using the doctor approved Ubie Symptom Checker.

1. Before You Begin

1. Wash your hands thoroughly with soap and water.

2. Assemble all supplies on a clean, flat surface:

   • Asfotase alfa vial (lyophilized powder)
   • Diluent vial (supplied with each vial of drug)
   • Two sterile syringes
   • Two sterile needles:
     • 21–23 gauge, 1–1.5 inch for reconstitution
     • 27–30 gauge, ½ inch for subcutaneous injection
   • Alcohol swabs
   • Sharps disposal container
   • Gloves (optional, but recommended)

3. Check the expiration dates on both vials.

4. Inspect vials for cracks, particulate matter, or discoloration. Do not use if anything looks abnormal.

2. Diluent and Drug Preparation

2.1 Warming to Room Temperature

• Allow both vials to sit at room temperature for 20–30 minutes.
• Do not use external heat sources or microwave.

2.2 Cleaning the Vial Stoppers

• Use an alcohol swab on each vial stopper.
• Let air-dry for at least 30 seconds—do not blow on them.

3. Reconstitution Technique

1. Attach the 21–23 gauge needle to your syringe (e.g., 1 mL or 3 mL, depending on the volume of diluent).

2. Withdraw the diluent:

   • Pull back plunger to the correct volume line (as prescribed).
   • Insert needle into diluent vial at a slight angle.
   • Inject air into the vial to equalize pressure.
   • Turn vial upright; slowly withdraw diluent, avoiding bubbles.

3. Inject diluent into the drug vial:

   • Hold the drug vial upright.
   • Slowly push the diluent down the vial wall (not directly onto the powder) to minimize foaming.

4. Gently mix:

   • Swirl the vial gently in a circular motion.
   • Do not shake, invert, or tap—excessive agitation can denature the enzyme.
   • Continue swirling until the powder is fully dissolved and the solution is clear or slightly opalescent.

5. Inspect solution:

   • No visible particles or cloudiness (beyond slight opalescence).
   • If particulate remains, discard and reconstitute a new vial.

4. Selecting the Right Needle Gauge

• Reconstitution needle: 21–23 gauge, 1–1.5 inch
  • Larger bore helps withdraw viscous diluent more easily.
• Injection needle: 27–30 gauge, ½ inch
  • Thin gauge minimizes injection pain.
  • Short length reduces risk of intramuscular injection if subcutaneous is intended.

Always change needles between reconstitution and injection to avoid dulling, which can increase discomfort and compromise sterility.

5. Drawing Up the Dose

1. Swap to the injection needle:

   • Remove the reconstitution needle and immediately cap the syringe.
   • Attach the 27–30 gauge needle carefully.

2. Withdraw the dose:

   • Gently invert the vial.
   • Insert needle, pull back plunger to prescribed dose.
   • Keep the needle tip below the fluid line.

3. Remove air bubbles:

   • Tap syringe lightly until bubbles rise.
   • Push plunger until a small droplet appears at the tip.

6. Injection Site Selection

Asfotase alfa is administered subcutaneously (SC). Rotate sites to reduce local irritation.

Common sites include:

• Abdomen (avoiding the 2-inch area around the navel)
• Anterior thighs
• Upper outer arms (if self-administering or with assistance)
• Upper buttocks or flank areas

Rotate sites in a clockwise or counterclockwise pattern, waiting at least 1 inch from the last site.

7. Injection Technique

1. Clean the site:

   • Wipe skin with alcohol swab in a circular motion.
   • Allow to air-dry completely.

2. Pinch the skin:

   • Grasp a fold of skin with thumb and forefinger (especially in thinner patients).
   • For patients with more subcutaneous tissue, stretching the skin flat may be acceptable.

3. Insert the needle:

   • At a 45- to 90-degree angle (more acute for lean patients).
   • Steady, quick motion reduces discomfort.

4. Inject the drug:

   • Hold syringe steady.
   • Depress plunger slowly and evenly until the full dose is delivered.

5. Withdraw the needle:

   • Remove at the same angle of insertion.
   • Release the skin fold.

6. Apply gentle pressure:

   • Use a clean cotton ball or gauze pad.
   • No need to rub; just hold for 5–10 seconds.
   • A small bandage may be applied if there’s minor bleeding.

8. Aftercare and Monitoring

• Observe for immediate reactions (first 30 minutes):
  • Redness, swelling, itching, or pain at the injection site
  • Systemic symptoms (e.g., fever, chills, difficulty breathing)
• Document:
  • Date, time, dose, and site of injection
  • Any reactions or patient comments
• Rotate sites next dose to minimize tissue irritation.

When to Seek Help

• Severe pain, excessive swelling, or signs of infection (red streaks, warmth, pus) at injection site
• Signs of allergic reaction: hives, lip/tongue swelling, difficulty breathing, rapid heart rate
• Any new or worsening symptoms that concern you—speak to a doctor right away. You can also try a free, online symptom check, using the doctor approved Ubie Symptom Checker.

9. Safe Disposal

• Place used needles and syringes in a FDA-approved sharps container immediately.
• Do not recap needles.
• Once full, follow your facility’s or community guidelines for sharps disposal.

10. Tips for Success

• Practice good hand hygiene before and after each injection.
• Stay calm and confident—a relaxed technique reduces patient anxiety and pain.
• Keep a logbook of doses and sites to ensure proper rotation.
• Store reconstituted solution in the refrigerator if not used immediately; discard after recommended timeframe (per prescribing information, typically 24 hours at 2–8 °C and used within that period).
• Educate the patient or caregiver: demonstrate the process, observe them doing it, and answer questions.

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Proper technique in reconstituting and injecting asfotase alfa ensures that patients receive the full therapeutic benefit with minimal discomfort and risk. Always adhere to the manufacturer’s prescribing information and your facility’s protocols. If you have any concerns about serious or life-threatening symptoms, please speak to a doctor immediately.