Skytrofa 13.3mg Inj Cartridge

Manufacturer ASCENDIS PHARMA Active Ingredient Lonapegsomatropin Injection(LOE na peg SOE ma TROE pin) Pronunciation LOE-na-peg-SOE-ma-TROE-pin
It is used to help with growth and to treat growth hormone deficiency.
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Drug Class
Growth Hormone
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Pharmacologic Class
Recombinant human growth hormone (rhGH) analog; PEGylated somatropin
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Pregnancy Category
Not available
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FDA Approved
Aug 2021
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DEA Schedule
Not Controlled

Overview

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What is this medicine?

Skytrofa is a medicine given as a shot once a week to children who are not growing as they should because their bodies don't make enough natural growth hormone. It helps them grow taller.
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How to Use This Medicine

Administering This Medication

To ensure your child receives this medication correctly, follow the instructions provided by their doctor. Carefully read all accompanying information and follow the instructions precisely. This medication is administered via injection into the fatty tissue on the right or left side of the stomach, thigh, or buttocks.

If you will be giving your child the injection, their doctor or nurse will provide guidance on the proper technique. It is essential that you understand how to use this medication. Refer to the instructions for use that come with the medication, and if you have any questions or concerns, consult with the doctor or pharmacist.

Before administering the injection, remove the medication from the refrigerator and let it sit at room temperature for 15 minutes. Do not heat the medication. As instructed by the doctor, mix the medication before use, following the provided guidelines.

When administering the injection, rotate the injection site with each dose. Avoid injecting through clothing, and do not inject into skin that is irritated, bruised, red, infected, hard, or scarred. Wash your hands before and after handling the medication.

Do not use the medication if the solution appears cloudy, is leaking, or contains particles. Additionally, do not use the medication if the solution has changed color. After mixing, do not refrigerate the medication. Use the medication within 4 hours of preparation and discard any unused portion.

Disposal and Storage

Dispose of used needles and other sharp objects in a designated needle/sharp disposal box. Do not reuse needles or other items. When the disposal box is full, follow local regulations for proper disposal. If you have any questions, consult with a doctor or pharmacist.

Store the medication in the refrigerator, avoiding freezing temperatures. Keep the medication in its original carton to protect it from light. If necessary, you may store the medication at room temperature for up to 6 months. Record the date you remove the medication from the refrigerator, and you may return it to the refrigerator within the 6-month period. Discard the medication if it is not used within 6 months of removal from the refrigerator.

Missed Dose

If a dose is missed, administer it as soon as possible. However, if your child misses a dose by more than 2 days, skip the missed dose and resume the regular schedule. Do not administer two doses within 5 days of each other.
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Lifestyle & Tips

  • Administer the injection exactly as prescribed by your doctor, on the same day each week.
  • Store the medicine properly as instructed (refrigerated).
  • Do not shake the cartridge.
  • Rotate injection sites to prevent skin problems.
  • Maintain a healthy diet and regular exercise as recommended by your healthcare provider.
  • Attend all scheduled doctor appointments and lab tests to monitor treatment effectiveness and safety.

Dosing & Administration

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Adult Dosing

Standard Dose: Not indicated for adult growth hormone deficiency (GHD)
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Pediatric Dosing

Neonatal: Not established
Infant: Not established
Child: Initial dose: 0.24 mg/kg/week, administered once weekly by subcutaneous injection. Dose may be adjusted based on IGF-1 levels and clinical response, up to a maximum of 0.48 mg/kg/week. Administer on the same day each week.
Adolescent: Initial dose: 0.24 mg/kg/week, administered once weekly by subcutaneous injection. Dose may be adjusted based on IGF-1 levels and clinical response, up to a maximum of 0.48 mg/kg/week. Administer on the same day each week.
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Dose Adjustments

Renal Impairment:

Mild: No specific dose adjustment recommended, monitor closely.
Moderate: No specific dose adjustment recommended, monitor closely.
Severe: Use with caution; close monitoring of IGF-1 levels and clinical response is recommended.
Dialysis: Not available; use with caution and close monitoring.

Hepatic Impairment:

Mild: No specific dose adjustment recommended, monitor closely.
Moderate: No specific dose adjustment recommended, monitor closely.
Severe: Use with caution; close monitoring of IGF-1 levels and clinical response is recommended.

Pharmacology

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Mechanism of Action

Lonapegsomatropin is a prodrug of somatropin. It is a long-acting C-terminally PEGylated somatropin. The PEGylation allows for a prolonged half-life and sustained release of somatropin. Somatropin binds to specific growth hormone (GH) receptors on target cells, including chondrocytes, osteoblasts, and hepatocytes, stimulating linear growth in children with GHD. It also stimulates production of insulin-like growth factor-1 (IGF-1) and IGF-binding protein-3 (IGFBP-3).
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Pharmacokinetics

Absorption:

Bioavailability: Not explicitly quantified as a percentage for subcutaneous administration, but well absorbed.
Tmax: Approximately 75 hours (range 24-168 hours) for lonapegsomatropin-tcgd.
FoodEffect: Not applicable (subcutaneous injection).

Distribution:

Vd: Similar to endogenous GH (approximately 0.05-0.1 L/kg for somatropin).
ProteinBinding: Not extensively protein bound.
CnssPenetration: Limited

Elimination:

HalfLife: Approximately 25-30 hours (for lonapegsomatropin-tcgd, which releases somatropin). The effective half-life of the released somatropin is prolonged, allowing for weekly dosing.
Clearance: Not explicitly quantified for lonapegsomatropin-tcgd, but somatropin clearance is approximately 0.1-0.2 L/kg/hr.
ExcretionRoute: Primarily renal and hepatic.
Unchanged: Minimal
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Pharmacodynamics

OnsetOfAction: Growth effects are gradual, typically observed over months of treatment.
PeakEffect: Sustained elevation of IGF-1 levels observed with weekly dosing.
DurationOfAction: Approximately 7 days, allowing for once-weekly administration.

Safety & Warnings

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BLACK BOX WARNING

Increased mortality in patients with acute critical illness due to complications following open heart surgery, accidental trauma, or acute respiratory failure. Not for use in patients with Prader-Willi syndrome who are severely obese or have severe respiratory impairment due to risk of sudden death.
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Side Effects

Urgent Side Effects: Seek Medical Help Right Away

Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If your child exhibits any of the following symptoms, contact their doctor immediately or seek medical attention:

Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of high blood sugar, including:
+ Confusion
+ Feeling sleepy
+ Unusual thirst or hunger
+ Passing urine more often
+ Flushing
+ Fast breathing
+ Breath that smells like fruit
Signs of pancreatitis (pancreas problem), such as:
+ Severe stomach pain
+ Severe back pain
+ Severe upset stomach or vomiting
Signs of a weak adrenal gland, including:
+ Severe upset stomach or vomiting
+ Severe dizziness or passing out
+ Muscle weakness
+ Feeling very tired
+ Mood changes
+ Decreased appetite
+ Weight loss
Signs of low thyroid levels, such as:
+ Constipation
+ Sensitivity to cold
+ Memory problems
+ Mood changes
+ Burning, numbness, or tingling sensations that are not normal
Signs of infection, including:
+ Fever
+ Chills
+ Severe sore throat
+ Ear or sinus pain
+ Cough
+ Increased or changed sputum production
+ Pain while urinating
+ Mouth sores
+ Wounds that will not heal
A skin lump or growth
Changes in the color or size of a mole
Skin breakdown at the site of application
Unexplained bruising or bleeding
Muscle or joint pain
Burning, numbness, pain, or tingling in the hands, arms, wrists, legs, or feet
Children using this medication can rarely experience a bone problem in the hip (slipped growth plate); seek medical attention if your child experiences hip or knee pain or a limp
Severe bone problems have been reported; contact the doctor if your child experiences new or worsening bone pain
Raised pressure in the head has rarely occurred, particularly in patients with Turner syndrome or Prader-Willi syndrome; seek medical attention if your child exhibits:
+ Changes in vision
+ Severe headache
+ Upset stomach
+ Vomiting

Other Possible Side Effects

While many people do not experience side effects or only have mild ones, it is essential to monitor your child's health. If your child experiences any of the following side effects or any other symptoms that concern you, contact their doctor:

Upset stomach or vomiting
* Stomach pain or diarrhea

This is not an exhaustive list of potential side effects. If you have questions or concerns about side effects, consult your child's doctor for medical advice.
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Seek Immediate Medical Attention If You Experience:

  • Severe or persistent headache, especially with nausea, vomiting, or vision changes (e.g., blurred vision, double vision)
  • New or worsening limping, hip pain, or knee pain
  • New or worsening back pain or curvature of the spine
  • Signs of an allergic reaction (e.g., rash, hives, swelling of the face/lips/tongue, difficulty breathing)
  • Increased thirst, increased urination, or unusual fatigue (signs of high blood sugar)
  • Any new or unusual skin growths or changes in existing moles
  • Swelling in hands or feet
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Before Using This Medicine

Before Your Child Takes This Medication: Important Information to Share with Your Doctor

It is essential to inform your doctor about the following:

If your child is allergic to this medication, any of its components, or any other substances, including foods or drugs. Please describe the allergic reaction and its symptoms.
If your child has any of the following health conditions:
+ Breathing problems, such as sleep apnea
+ Cancer or other tumors, including brain tumors
+ Diabetic eye disease
+ Recent illness after open heart surgery, stomach surgery, or accidental injury
If your child has Prader-Willi syndrome and is severely overweight, experiences breathing difficulties, or has sleep apnea
If your child's bones have stopped growing (closed epiphyses)

This list is not exhaustive, and it is crucial to discuss all of your child's medications (prescription, over-the-counter, natural products, and vitamins) and health problems with the doctor and pharmacist. To ensure safe treatment, verify that it is safe to administer this medication with all of your child's other medications and health conditions. Never start, stop, or adjust the dosage of any medication without consulting your doctor.
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Precautions & Cautions

It is essential to inform all of your child's healthcare providers, including doctors, nurses, pharmacists, and dentists, that your child is taking this medication.

Your child may be at risk for high blood sugar, including the development of new-onset diabetes or worsening of existing diabetes. As directed by the doctor, regularly check your child's blood sugar levels to monitor for any changes. Additionally, adhere to the recommended schedule for your child's blood work and eye exams to ensure their health is closely monitored.

This medication may interfere with certain laboratory tests. Therefore, it is crucial to notify all healthcare providers and laboratory personnel that your child is taking this drug to avoid any potential inaccuracies in test results.

If your child experiences any changes in weight, consult with the doctor, as the dosage of this medication may need to be adjusted accordingly.

To prevent the transmission of infections, do not share this product, needles, or syringes with anyone, even if the needle has been changed. Sharing can spread infections, including those that may not be immediately apparent.

One of the potential side effects of this medication is an excess of fluid in the body, which can lead to heart failure in some cases. If your child exhibits symptoms such as shortness of breath, significant weight gain, or swelling in the arms or legs, contact the doctor immediately.

If your child has a pre-existing abnormal curvature of the spine (scoliosis), discuss this with the doctor, as this medication may exacerbate the condition in children who are still growing.

In children with a history of cancer or tumors, the use of this medication may increase the risk of cancer or tumor growth. Additionally, the development of new tumors may be more likely in some patients. Consult with the doctor to discuss the potential risks and benefits.

Children with Prader-Willi syndrome are at a higher risk for severe and potentially life-threatening lung or breathing problems. This risk may be increased in children who have sleep apnea, lung or airway infections, airway blockages, or are severely overweight. If your child has a fever of 100.4°F (38°C) or higher, cough, sore throat, shortness of breath, chest pain or discomfort, new or worsening snoring, or abnormal breathing during sleep, contact the doctor immediately.

If your child is pregnant or breastfeeding, it is essential to discuss the potential benefits and risks of this medication with the doctor. This will help determine the best course of action for both your child and the baby.
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Overdose Information

Overdose Symptoms:

  • Acute overdose: Initial hypoglycemia followed by hyperglycemia.
  • Chronic overdose: Signs and symptoms of gigantism (in children) or acromegaly (in adults), such as enlarged hands/feet, joint pain, excessive sweating, and other metabolic disturbances.

What to Do:

Seek immediate medical attention. Call 911 or your local emergency number. For poison control, call 1-800-222-1222. Management is supportive and symptomatic.

Drug Interactions

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Major Interactions

  • Glucocorticoids (may inhibit growth-promoting effects)
  • Insulin and/or other antidiabetic agents (may decrease insulin sensitivity, requiring dose adjustment)
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Moderate Interactions

  • Thyroid hormones (may need dose adjustment of thyroid hormones)
  • CYP450-metabolized drugs (e.g., corticosteroids, sex steroids, cyclosporine, anticonvulsants - somatropin may induce CYP3A4, potentially altering metabolism)

Monitoring

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Baseline Monitoring

Height and Weight

Rationale: To establish baseline growth velocity and calculate initial dose.

Timing: Prior to initiation of therapy.

IGF-1 and IGFBP-3 levels

Rationale: To confirm GHD diagnosis and establish baseline for monitoring treatment response.

Timing: Prior to initiation of therapy.

Thyroid Function (TSH, Free T4)

Rationale: To rule out hypothyroidism, which can mimic GHD or impair response to GH therapy.

Timing: Prior to initiation of therapy.

Fasting Glucose and/or HbA1c

Rationale: To assess glucose metabolism, as GH can affect insulin sensitivity.

Timing: Prior to initiation of therapy.

Bone Age

Rationale: To assess skeletal maturity and predict adult height potential.

Timing: Prior to initiation of therapy.

Fundoscopic Examination

Rationale: To screen for papilledema, a sign of benign intracranial hypertension.

Timing: Prior to initiation of therapy, and if symptoms develop.

Scoliosis Assessment

Rationale: To screen for pre-existing scoliosis, which may progress during rapid growth.

Timing: Prior to initiation of therapy.

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Routine Monitoring

Height and Weight

Frequency: Quarterly (every 3 months)

Target: Increased growth velocity, appropriate weight gain.

Action Threshold: Lack of adequate growth response may indicate need for dose adjustment or re-evaluation.

IGF-1 levels

Frequency: 4-6 weeks after dose change, then every 3-6 months

Target: Within age- and sex-appropriate reference ranges (e.g., 0 to +2 SDS).

Action Threshold: Levels consistently above +2 SDS may indicate need for dose reduction; levels consistently below -2 SDS may indicate need for dose increase.

Thyroid Function (TSH, Free T4)

Frequency: Annually, or as clinically indicated (e.g., if symptoms of hypothyroidism develop).

Target: Within normal limits for age.

Action Threshold: Abnormal levels require evaluation and potential thyroid hormone replacement.

Fasting Glucose and/or HbA1c

Frequency: Annually

Target: Within normal limits for age.

Action Threshold: Elevated levels require further evaluation for glucose intolerance or diabetes.

Fundoscopic Examination

Frequency: As clinically indicated (e.g., if symptoms of headache, visual changes, nausea/vomiting develop).

Target: No papilledema.

Action Threshold: Presence of papilledema requires immediate evaluation and potential discontinuation of therapy.

Scoliosis Assessment

Frequency: Annually, or as clinically indicated.

Target: No significant progression of scoliosis.

Action Threshold: Significant progression requires orthopedic evaluation.

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Symptom Monitoring

  • Severe or persistent headache
  • Visual changes (e.g., blurred vision, double vision)
  • Nausea and/or vomiting
  • Limping or new hip/knee pain (slipped capital femoral epiphysis)
  • New or worsening back pain (scoliosis progression)
  • Signs of allergic reaction (e.g., rash, itching, swelling, difficulty breathing)
  • Signs of high blood sugar (e.g., increased thirst, increased urination, fatigue)
  • Changes in skin lesions (e.g., moles, birthmarks) for malignancy risk

Special Patient Groups

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Pregnancy

There are no adequate and well-controlled studies of lonapegsomatropin in pregnant women. Animal reproduction studies have not been conducted. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Trimester-Specific Risks:

First Trimester: Risk unknown; avoid unless clearly necessary.
Second Trimester: Risk unknown; avoid unless clearly necessary.
Third Trimester: Risk unknown; avoid unless clearly necessary.
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Lactation

It is unknown whether lonapegsomatropin is excreted in human milk. Many drugs are excreted in human milk, and there is a potential for serious adverse reactions in the breastfed infant from lonapegsomatropin. A decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Infant Risk: L3 (Moderate risk) - Potential for adverse effects on infant growth or metabolism, though large protein molecules are generally poorly transferred into milk.
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Pediatric Use

Skytrofa is indicated for the treatment of pediatric patients 1 year and older with growth hormone deficiency. Safety and effectiveness in infants younger than 1 year have not been established.

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Geriatric Use

Not indicated for geriatric patients. Safety and efficacy have not been established in this population.

Clinical Information

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Clinical Pearls

  • Skytrofa is a once-weekly subcutaneous injection, offering a significant convenience advantage over daily growth hormone injections, which may improve adherence.
  • Dosing is weight-based and should be individualized based on IGF-1 levels and clinical response, aiming for IGF-1 levels within the age- and sex-appropriate reference range.
  • Patients and caregivers must be thoroughly trained on proper injection technique, site rotation, and storage.
  • Monitor for potential adverse effects common to growth hormone therapy, including benign intracranial hypertension, slipped capital femoral epiphysis, scoliosis progression, and glucose intolerance.
  • Regular monitoring of IGF-1, thyroid function, and glucose metabolism is crucial for safe and effective treatment.
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Alternative Therapies

  • Other recombinant human growth hormone (rhGH) products (daily injections): Somatropin (e.g., Genotropin, Humatrope, Norditropin, Nutropin, Omnitrope, Saizen, Zomacton)
  • Other long-acting rhGH products: Somatrogon (Ngenla), Somapacitan (Sogroya - for adult GHD)
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Cost & Coverage

Average Cost: Highly variable, typically several thousand dollars per month per cartridge
Insurance Coverage: Specialty Tier (requires prior authorization and often subject to step therapy)
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General Drug Facts

If your child's symptoms or health issues persist or worsen, it is essential to contact their doctor promptly. To ensure safe and effective treatment, never share your child's medication with others, and do not administer someone else's medication to your child. Some medications may include an additional patient information leaflet; if you have questions or concerns about this medication, consult with your child's doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately contact your local poison control center or seek urgent medical attention. When reporting the incident, be prepared to provide detailed information, including the substance taken, the quantity, and the time it occurred.