Dosage & Administration
Perinatal/Infantile-Onset HPP ( 2.2)
Juvenile-Onset HPP ( 2.3)
Preparation and Weight-Based Dosing ( 2.4):
Administration ( 2.5):
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Strensiq Prescribing Information
Patients treated with enzyme replacement therapies have experienced life-threatening hypersensitivity reactions, including anaphylaxis. Anaphylaxis has occurred during the early course of enzyme replacement therapy and after extended duration of therapy.
Initiate STRENSIQ under the supervision of a healthcare provider with appropriate medical monitoring and support measures. If a severe hypersensitivity reaction (e.g., anaphylaxis) occurs, discontinue STRENSIQ and immediately initiate appropriate medical treatment, including use of epinephrine. Inform patients of the symptoms of life-threatening hypersensitivity reactions, including anaphylaxis and to seek immediate medical care should symptoms occur [see Warnings and Precautions (5.1)].
STRENSIQ® is indicated for the treatment of patients with perinatal/infantile- and juvenile-onset hypophosphatasia (HPP).
Recommendations Prior to STRENSIQ Treatment
Initiate STRENSIQ under the supervision of a healthcare provider with appropriate medical monitoring and support measures [see Warnings and Precautions (5.1)].
Dosage for Perinatal/Infantile-Onset HPP
The recommended dosage regimen of STRENSIQ for the treatment of perinatal/infantile-onset HPP is 6 mg/kg per week administered subcutaneously as either:
- 2 mg/kg three times per week, or
- 1 mg/kg six times per week. Injection site reactions may limit the tolerability of the six times per week regimen [see Adverse Reactions (6.1)].
The dose of STRENSIQ may be increased for lack of efficacy (e.g., no improvement in respiratory status, growth, or radiographic findings) up to 9 mg/kg per week administered subcutaneously as 3 mg/kg three times per week.
Dosage for Juvenile-Onset HPP
The recommended dosage regimen of STRENSIQ for the treatment of juvenile-onset HPP is 6 mg/kg per week administered subcutaneously as either:
- 2 mg/kg three times per week, or
- 1 mg/kg six times per week. Injection site reactions may limit the tolerability of the six times per week regimen [see Adverse Reactions (6.1)].
Preparation and Weight-Based Dosing Tables
Caution: Do not use the 80 mg/0.8 mL vial of STRENSIQ in pediatric patients weighing less than 40 kg because the systemic exposure of asfotase alfa achieved with the 80 mg/0.8 mL vial (higher concentration) is lower than that achieved with the other strength vials (lower concentration). A lower exposure may not be adequate for this subgroup of patients [see Dosage Forms and Strengths (3), Clinical Pharmacology (12.3)].
- 1.
- Determine the total weekly volume needed for the prescribed dosage based on the patient's weight and recommended dosage. Follow these steps to determine the patient dose.
- Total weekly dose (mg) = patient's weight (kg) × prescribed dose (mg/kg/week)
- Total injection volume (mL) per week = Total dose (mg/week) divided by the STRENSIQ concentration (40 mg/mL or 100 mg/mL). Note product concentrations are: 40 mg/mL (vial strengths 18 mg/0.45 mL, 28 mg/0.7 mL, 40 mg/mL) or 100 mg/mL (vial strength 80 mg/0.8 mL).
- Round total injection volume to the nearest hundredth of a mL
- Total number of vials per week = Total injection volume divided by vial volume (mL)
- 2.
- Determine the number of injection days per week (three or six per week).
- 3.
- Determine dose per injection day. Patient weights should be rounded to the nearest kilogram when determining dose. Use the following tables for guidance, for patients administering 2 mg/kg three times per week (Table 1), 1 mg/kg six times per week (Table 2) and for dose escalations to 3 mg/kg three times per week, recommended only for patients with perinatal/infantile-onset HPP [see Dosage and Administration (2.2)] (Table 3).
| Body Weight (kg) * | Dose to Inject | Volume to Inject | Vial Configuration |
|---|---|---|---|
| |||
| 3 | 6 mg | 0.15 mL | 18 mg/0.45 mL |
| 4 | 8 mg | 0.2 mL | 18 mg/0.45 mL |
| 5 | 10 mg | 0.25 mL | 18 mg/0.45 mL |
| 6 | 12 mg | 0.3 mL | 18 mg/0.45 mL |
| 7 | 14 mg | 0.35 mL | 18 mg/0.45 mL |
| 8 | 16 mg | 0.4 mL | 18 mg/0.45 mL |
| 9 | 18 mg | 0.45 mL | 18 mg/0.45 mL |
| 10 | 20 mg | 0.5 mL | 28 mg/0.7 mL |
| 15 | 30 mg | 0.75 mL | 40 mg/1 mL |
| 20 | 40 mg | 1 mL | 40 mg/1 mL |
| 25 | 50 mg | 1.25 mL | Two 28 mg/0.7 mL vials |
| 30 | 60 mg | 1.5 mL | Two 40 mg/1 mL vials |
| 35 | 70 mg | 1.75 mL | Two 40 mg/1 mL vials |
| 40 | 80 mg | 0.8 mL | 80 mg/0.8 mL |
| 50 | 100 mg | 1 mL | Two 80 mg/0.8 mL vials |
| 60 | 120 mg | 1.2 mL † | Two 80 mg/0.8 mL vials |
| 70 | 140 mg | 1.4 mL † | Two 80 mg/0.8 mL vials |
| 80 | 160 mg | 1.6 mL † | Two 80 mg/0.8 mL vials |
| Body Weight (kg) * | Dose to Inject | Volume to Inject | Vial Configuration |
|---|---|---|---|
| |||
| 3 | 3 mg | 0.08 mL | 18 mg/0.45 mL |
| 4 | 4 mg | 0.1 mL | 18 mg/0.45 mL |
| 5 | 5 mg | 0.13 mL | 18 mg/0.45 mL |
| 6 | 6 mg | 0.15 mL | 18 mg/0.45 mL |
| 7 | 7 mg | 0.18 mL | 18 mg/0.45 mL |
| 8 | 8 mg | 0.2 mL | 18 mg/0.45 mL |
| 9 | 9 mg | 0.23 mL | 18 mg/0.45 mL |
| 10 | 10 mg | 0.25 mL | 18 mg/0.45 mL |
| 15 | 15 mg | 0.38 mL | 18 mg/0.45 mL |
| 20 | 20 mg | 0.5 mL | 28 mg/0.7 mL |
| 25 | 25 mg | 0.63 mL | 28 mg/0.7 mL |
| 30 | 30 mg | 0.75 mL | 40 mg/1 mL |
| 35 | 35 mg | 0.88 mL | 40 mg/1 mL |
| 40 | 40 mg | 1 mL | 40 mg/1 mL |
| 50 | 50 mg | 0.5 mL | 80 mg/0.8 mL |
| 60 | 60 mg | 0.6 mL | 80 mg/0.8 mL |
| 70 | 70 mg | 0.7 mL | 80 mg/0.8 mL |
| 80 | 80 mg | 0.8 mL | 80 mg/0.8 mL |
| 90 | 90 mg | 0.9 mL | Two 80 mg/0.8 mL vials |
| 100 | 100 mg | 1 mL | Two 80 mg/0.8 mL vials |
| Body Weight (kg) † | Dose to Inject | Volume to Inject | Vial Configuration |
|---|---|---|---|
| |||
| 3 | 9 mg | 0.23 mL | 18 mg/0.45 mL |
| 4 | 12 mg | 0.3 mL | 18 mg/0.45 mL |
| 5 | 15 mg | 0.38 mL | 18 mg/0.45 mL |
| 6 | 18 mg | 0.45 mL | 18 mg/0.45 mL |
| 7 | 21 mg | 0.53 mL | 28 mg/0.7 mL |
| 8 | 24 mg | 0.6 mL | 28 mg/0.7 mL |
| 9 | 27 mg | 0.68 mL | 28 mg/0.7 mL |
| 10 | 30 mg | 0.75 mL | 40 mg/1 mL |
| 15 | 45 mg | 1.13 mL ‡ | Two 28 mg/0.7 mL vials |
| 20 | 60 mg | 1.5 mL ‡ | Two 40 mg/1 mL vials |
| 25 | 75 mg | 1.88 mL ‡ | Two 40 mg/1 mL vials |
- 4.
- Take the unopened STRENSIQ vial(s) out of the refrigerator 15 to 30 minutes before injecting to allow the liquid to reach room temperature.
Do not warm STRENSIQ in any other way (for example, do not warm it in a microwave or in hot water). - 5.
- Inspect the solution in the vial(s) for particulate matter and discoloration. STRENSIQ is supplied as a clear, slightly opalescent or opalescent, colorless to slightly yellow aqueous solution; a few small translucent or white particles may be present. Discard any vial(s) not consistent with this appearance.
- 6.
- Assemble injection supplies. Administer STRENSIQ using sterile disposable 1 mL syringes and ½ inch injection needles, between 25 to 29 gauge are recommended. The use of two different gauge needles is recommended, a larger bore needle (e.g. 25 gauge) for withdrawal of the medication, and a smaller bore needle (e.g. 29 gauge) for the injection. For doses greater than 1 mL, the injection volume should be split equally between two 1 mL syringes. Always use a new syringe and needle for each injection.
- 7.
- Remove vial cap, aseptically prepare the vial and insert the syringe into the vial to withdraw the prescribed dose for administration. Do not shake.
- 8.
- Remove any air bubbles in the syringe and verify the correct dose.
- 9.
- STRENSIQ vials are for one time use only. Discard any unused product.
Administration
STRENSIQ is for subcutaneous injection only.
- When administering two injections, use two separate injection sites.
- Administer STRENSIQ within 3 hours upon removal of the vial(s) from refrigeration.
- Rotate the injection from among the following sites to reduce the risk of lipodystrophy: abdominal area, thigh, deltoid, or buttocks [see Warnings and Precautions (5.2), Adverse Reactions (6.1)].
- Do NOT administer injections in areas that are reddened, inflamed, or swollen.
- Inject STRENSIQ subcutaneously into the determined site and properly dispose of the syringe and the needle.
STRENSIQ is a clear, slightly opalescent or opalescent, colorless to slightly yellow aqueous solution; few small translucent or white particles may be present. The product is available as:
- Injection: 18 mg/0.45 mL, 28 mg/0.7 mL, 40 mg/mL, or 80 mg/0.8 mL solution in single-dose vials
Pregnancy
Risk Summary
There are no available data on STRENSIQ use in pregnant women to inform a drug associated risk. In animal reproduction studies, asfotase alfa administered intravenously to pregnant rats and rabbits during the period of organogenesis showed no evidence of fetotoxicity, embryolethality or teratogenicity at doses causing plasma exposures up to 21 and 24 times, respectively, the exposure at the recommended human dose (see Data).
In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.
Data
Animal Data
Asfotase alfa administered during the period of organogenesis to rats (from gestation Day 6 to Day 19 post-partum) and rabbits (on gestation days 7 to 19) at intravenous doses up to 50 mg/kg/day, approximately 21 and 24 times the human AUC of 65486 ng.h/mL at 2 mg/kg dose administered three times weekly for a 50 kg individual, respectively did not cause any adverse effects on embryofetal development. A pre- and post-natal development study in pregnant rats showed no evidence of adverse effects on pre- and post-natal development at intravenous doses (from Day 6 of gestation to Day 19 postpartum) of asfotase alfa up to 50 mg/kg/day approximately 21 times the human AUC of 65486 ng.h/mL at 2 mg/kg dose administered three times weekly for a 50 kg individual.
Lactation
Risk Summary
There are no data on the presence of asfotase alfa in human milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for STRENSIQ and any potential adverse effects on the breastfed infant from asfotase alfa or from the underlying maternal condition.
Pediatric Use
The safety and effectiveness of STRENSIQ for the treatment of perinatal/infantile- and juvenile-onset HPP have been established in pediatric patients. Use of STRENSIQ for this indication is based on 4 prospective, open-label clinical trials conducted in 89 pediatric patients with perinatal/infantile-onset or juvenile-onset HPP [see Clinical Studies (14)].
Geriatric Use
No patients with perinatal/infantile- or juvenile-onset HPP aged 65 years were enrolled in clinical trials of STRENSIQ. Therefore, there is no information available to determine whether patients aged 65 years and over respond differently from younger patients.
None.