Strensiq (asfotase alfa)
Metabolic Disease Enzyme Replacement - Hypophosphatasia Subcutaneous Vial (Ml)
Last reviewed · Source: First Databank (FDB) drug data
Overview
Asfotase alfa is a biosynthetic (recombinant DNA origin) form of human tissue-nonspecific alkaline phosphatase (TNSALP), a metalloenzyme that catalyzes the hydrolysis of phosphomonoesters.
Asfotase alfa is a biosynthetic (recombinant DNA origin) form of tissue-nonspecific alkaline phosphatase (TNSALP), a metalloenzyme that catalyzes the hydrolysis of phosphomonoesters, resulting in the release of inorganic phosphate (a precursor of calcium phosphate) and alcohol. The specific activity of asfotase alfa is 620-1250 units/mg, with 1 unit defined as the amount of asfotase alfa that results in the formation of 1 mcmol of p-nitrophenol from p-nitrophenyl phosphate per minute at 37degreesC. Asfotase alfa is a soluble glycoprotein composed of 2 identical polypeptide chains, each containing 726 amino acids covalently linked by 2 disulfide bonds.
Each polypeptide chain consists of the catalytic domain of human TNSALP, the human immunoglobulin G1 (IgG1) Fc domain, and a deca-aspartate peptide used as a bone-targeting domain. The drug is produced using a Chinese hamster ovary cell line.
Hypophosphatasia (HPP) is caused by a deficiency in TNSALP activity, which results in elevations in several TNSALP substrates, including inorganic pyrophosphate and pyridoxal 5'-phosphate. In patients with this condition, asfotase alfa therapy replaces the TNSALP enzyme, reducing accumulation of TNSALP substrates, promoting bone mineralization, and improving skeletal structure. In patients with perinatal/infantile- or juvenile-onset HPP, treatment with asfotase alfa caused reductions in plasma TNSALP substrates, inorganic pyrophosphate and pyridoxal 5'-phosphate, within 6-12 weeks of treatment.
However, reductions in plasma TNSALP substrate concentrations did not correlate with clinical outcomes. Bone biopsy data from patients with perinatal/infantile-onset or juvenile-onset HPP receiving asfotase alfa demonstrated decreases in osteoid volume and thickness indicating improved bone mineralization.
Asfotase alfa appears to exhibit time-independent pharmacokinetics. Pharmacokinetics of the drug were dose-proportional across a dosage range of 0.3-3 mg/kg once every other day (three times weekly) in patients with HPP. The estimated absolute bioavailability of the drug following subcutaneous administration is approximately 62%.
Steady-state exposure was achieved as early as 3 weeks after administration of the first dose. An elimination half-life of approximately 5 days was reported following subcutaneous administration of the drug. Time to peak plasma concentrations following multiple subcutaneous doses of 2 mg/kg 3 times weekly in patients with HPP was approximately 15 or 21 hours in patients 5 years of age or younger or in those older than 5 to 12 years of age, respectively.
Body weight is a major covariate of asfotase alfa clearance, which supports weight-based dosing of the drug. The concentration of asfotase alfa injection affects drug exposure; at the same dosage, asfotase alfa exposure is approximately 25% lower with the 100-mg/mL concentration compared with that of the lower concentration (40 mg/mL). Formation of anti-drug antibodies reduces systemic exposure of asfotase alfa.
Pharmacokinetics of asfotase alfa were generally similar in patients with perinatal/infantile-onset HPP and those with juvenile-onset HPP.
Generic name: asfotase alfa
Drug class: Metabolic Disease Enzyme Replacement - Hypophosphatasia
Therapeutic class: Metabolic Disease Enzyme Replacement Agents
Reference product & biosimilars
No reference, biosimilar or interchangeable associated with this drug.
Today’s intelligence on Strensiq
Indications
The following indications are listed for Strensiq:
- Childhood Hypophosphatasia
- Infantile Hypophosphatasia
Also known as: Childhood Hpp, Childhood-Type Hypophosphatasia, Fetal Hpp, Fetal Hypophosphatasia, Infantile Hpp, Infantile-Type Hypophosphatasia, Juvenile Hpp, Juvenile Hypophosphatasia, Perinatal Hypophosphatasia.
Dosing
Dosage of asfotase alfa is based on patient weight. The patient's weight should be rounded to the nearest kg when determining dosage of the drug.
The calculated total injection volume should be rounded to the nearest 0.01 mL. When the total injection volume exceeds 1 mL, the volume should be divided equally into 2 syringes and injected at separate sites.
For more detailed information on weight-based dosage of this drug by treatment regimen as well as required volume of injection and concentration and number of vials, the dosage tables in the manufacturer's labeling should be consulted.
Asfotase alfa is administered by subcutaneous injection only.
The manufacturer states that the 80 mg/0.8 mL vial of asfotase alfa should not be used in pediatric patients weighing less than 40 kg, because the systemic exposure of asfotase alfa achieved with this concentration is lower than that achieved with other strength vials. The lower exposure achieved with the 80 mg/0.8 mL vial may provide inadequate efficacy in such patients.
Vials of asfotase alfa injection should be inspected for particulate matter and discoloration prior to use. Asfotase alfa injection should be clear, slightly opalescent or opalescent, and colorless to slightly yellow, possibly with a few small translucent or white particles; solutions not consistent with this appearance should be discarded. Unopened vials of asfotase alfa should be removed from refrigeration 15 to 30 minutes before injecting to allow for the medication to reach room temperature; asfotase alfa should not be warmed in any other manner. Asfotase alfa injection should be administered within 3 hours of removing the vial(s) from refrigeration. Vials of asfotase alfa injection are preservative-free and are for single use only; any unused solution should be discarded.
Asfotase alfa injection should be administered using disposable 1-mL syringes and 1/2-inch, 25- to 29-gauge needles; a new syringe and needle should be used for each injection. The use of 2 different gauge needles is recommended--a larger bore (e.g., 25 gauge) needle for medication withdrawal and a smaller bore (e.g., 29 gauge) needle for the injection. To reduce the risk of lipodystrophy, injection sites should be rotated at the abdominal, thigh, deltoid, and buttock areas. Injection into areas that are reddened, inflamed, or swollen should be avoided.
Vials of asfotase alfa should be stored in the original carton at 2-8degreesC and protected from light. Do not freeze or shake asfotase alfa vials.
No dosing information is available for this tab.
No dosing information is available for this tab.
Drug interactions
Formal drug-drug interaction studies have not been performed to date.
Studies have revealed analytical interference between asfotase alfa and laboratory tests that utilize an alkaline phosphatase-conjugated test system, which results in incorrect test results in patients administered asfotase alfa. These test systems are utilized to measure substances such as hormones, bacterial antigens, and antibodies. Laboratory assays which do not have alkaline phosphatase-conjugate technology are recommended for use when testing samples from patients receiving asfotase alfa. Laboratory personnel should be informed that a patient is being treated with asfotase alfa and use of a testing platform which does not utilize an alkaline phosphatase-conjugated test system should be discussed.
Elevated levels of serum alkaline phosphatase are expected in patients administered asfotase alfa. Clinicians should not rely on serum alkaline phosphatase measurements for clinical decision making in these patients.
There are no contraindication interactions for this drug.
There are no severe interactions for this drug.
There are no moderate interactions for this drug.
Contraindications
*None.
There are no contraindication contraindications for this drug.
There are no severe contraindications for this drug.
- No disease contraindications
Adverse reactions
The most common adverse reactions (>=10%) with asfotase alfa in clinical trials include injection site reactions, lipodystrophy, ectopic calcifications, and hypersensitivity reactions.
More Frequent
- Hypersensitivity drug reaction
Rare or Very Rare
- Anaphylaxis
- Calcification of cornea
- Hepatitis
- Nephrocalcinosis
More Frequent
- Dyschromia
- Erythema
- Induration of skin
- Injection site sequelae
- Lipodystrophy
- Pruritus of skin
- Skin swelling
Less Frequent
- Skin atrophy
- Skin hypertrophy
Rare or Very Rare
- Chills
- Drug-induced pyridoxine deficiency
- Fever
- Flushing
- Headache disorder
- Hypocalcemia
- Irritability
- Oral hypoesthesia
- Skin rash
- Vomiting
Precautions
No enhanced messaging available.
The efficacy and safety of asfotase alfa have been established in pediatric patients with perinatal/infantile- and juvenile-onset HPP. Clinical evidence supporting use is based on results from 4 prospective, open-label clinical studies involving 89 pediatric patients with this condition.
No data on the use of asfotase alfa in pregnant women are available. In animal reproduction studies in rats and rabbits, IV administration of asfotase alfa (at dosages resulting in plasma exposures up to 21 and 24 times the exposure at the recommended human dosage, respectively) during the period of organogenesis resulted in no evidence of fetotoxicity, embryolethality, or teratogenicity.
It is not known whether asfotase alfa is distributed into human milk. The effects of the drug on milk production or on the breast-fed infant also are unknown. The known benefits of breast-feeding should be considered along with the mother's clinical need for asfotase alfa and any potential effects of the drug or disease on the infant.
Clinical studies of asfotase alfa did not include patients 65 years of age or older. It is not known whether geriatric patients respond differently than younger patients.
ICD codes
No ICD codes are available for this drug.
Formulary status
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Last reviewed · Source: First Databank (FDB) drug data
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