Skytrofa 3.6mg 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
Human Growth Hormone (hGH) analog, pegylated
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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 used to help children grow taller when their bodies don't make enough natural growth hormone. It's given as a shot under the skin once a week.
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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 of the skin, typically on the right or left side of the stomach, thigh, or buttocks.

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

Before use, if the medication has been stored in the refrigerator, allow it to reach room temperature for 15 minutes. Do not heat the medication. This medication requires mixing before administration; follow the instructions provided by the doctor to ensure proper preparation.

Important Administration Guidelines

Rotate the injection site with each dose to minimize the risk of tissue damage.
Avoid injecting through clothing.
Do not administer the medication into skin that is irritated, bruised, red, infected, hard, or scarred.
Wash your hands before and after handling the medication.
Inspect the solution before use; do not use if it appears cloudy, is leaking, or contains particles. Additionally, do not use the solution if it has changed color.
After mixing, do not refrigerate the medication.
Use the medication within 4 hours of preparation.
Dispose of needles and other sharp objects in a designated disposal box. Do not reuse needles or other items. When the box is full, follow local regulations for proper disposal. If you have any questions, consult with a doctor or pharmacist.

Storage and Disposal

Store this medication in the refrigerator to maintain its potency. Do not freeze the medication. Keep it in the original outer carton to protect it from light. If necessary, you can store the medication at room temperature for up to 6 months. Record the date you remove the medication from the refrigerator. You can return the medication to the refrigerator within the 6-month period. If the medication is not used within 6 months after removal from the refrigerator, discard it.

Missed Dose

If you miss a dose, 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 normal schedule. Do not administer two doses within 5 days of each other.
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Lifestyle & Tips

  • Store Skytrofa cartridges in the refrigerator (2Β°C to 8Β°C / 36Β°F to 46Β°F) in the original carton to protect from light.
  • Do not freeze. Do not use if frozen.
  • Once a cartridge is inserted into the Skytrofa Auto-Injector, it can be stored at room temperature (up to 25Β°C / 77Β°F) for up to 7 days.
  • Administer the injection subcutaneously (under the skin) once weekly, rotating injection sites (e.g., abdomen, thigh, buttocks).
  • Follow the instructions for use provided with the auto-injector carefully.
  • Do not share your Skytrofa pen or cartridges with anyone else, even if they have the same condition.

Dosing & Administration

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Adult Dosing

Standard Dose: Not indicated for adult GHD
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Pediatric Dosing

Neonatal: Not established
Infant: Not established
Child: Initial dose: 0.24 mg/kg once weekly subcutaneously. Dose may be adjusted based on IGF-1 levels and clinical response, up to a maximum of 0.48 mg/kg once weekly.
Adolescent: Initial dose: 0.24 mg/kg once weekly subcutaneously. Dose may be adjusted based on IGF-1 levels and clinical response, up to a maximum of 0.48 mg/kg once weekly.
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Dose Adjustments

Renal Impairment:

Mild: No specific dose adjustment recommended, but monitor IGF-1 levels and clinical response.
Moderate: No specific dose adjustment recommended, but monitor IGF-1 levels and clinical response.
Severe: No specific dose adjustment recommended, but monitor IGF-1 levels and clinical response.
Dialysis: No specific dose adjustment recommended, but monitor IGF-1 levels and clinical response.

Hepatic Impairment:

Mild: No specific dose adjustment recommended, but monitor IGF-1 levels and clinical response.
Moderate: No specific dose adjustment recommended, but monitor IGF-1 levels and clinical response.
Severe: No specific dose adjustment recommended, but monitor IGF-1 levels and clinical response.

Pharmacology

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Mechanism of Action

Lonapegsomatropin is a prodrug of somatropin. Following subcutaneous administration, lonapegsomatropin undergoes proteolytic cleavage to release somatropin. Somatropin binds to specific growth hormone (GH) receptors on target cells, including chondrocytes, osteoblasts, and hepatocytes, stimulating linear growth, protein synthesis, and lipid metabolism. Its primary effects are mediated through insulin-like growth factor-1 (IGF-1), which is produced in the liver and other tissues.
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Pharmacokinetics

Absorption:

Bioavailability: Not available (subcutaneous)
Tmax: Approximately 2-3 days (for released somatropin)
FoodEffect: Not applicable (injectable)

Distribution:

Vd: Not available
ProteinBinding: Not available
CnssPenetration: Limited

Elimination:

HalfLife: Approximately 25-30 hours (effective half-life of released somatropin, allowing for once-weekly dosing)
Clearance: Not available
ExcretionRoute: Renal and hepatic
Unchanged: Not available
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Pharmacodynamics

OnsetOfAction: Within days (IGF-1 levels begin to rise)
PeakEffect: Within weeks (for growth velocity)
DurationOfAction: Approximately 7 days (due to pegylation and slow release of somatropin)

Safety & Warnings

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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 or seek medical attention immediately:

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 has hip or knee pain or a limp
Severe bone problems have occurred with this medication; 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 help if your child exhibits:
+ Changes in vision
+ Severe headache
+ Upset stomach
+ Vomiting

Other Possible Side Effects

As with all medications, some people may experience side effects. If your child has any of the following side effects or if they bother your child or do not go away, 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. Always contact their doctor for medical advice regarding side effects.
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Seek Immediate Medical Attention If You Experience:

  • Severe or new headaches, especially if accompanied by nausea, vomiting, or vision changes (could be signs of increased pressure in the brain).
  • Limping or new hip/knee pain (could be a sign of a slipped growth plate in the hip).
  • Worsening of a curved spine (scoliosis).
  • Changes in moles or skin lesions.
  • Signs of an allergic reaction: rash, hives, swelling of the face, lips, tongue, or throat, difficulty breathing.
  • Increased thirst or urination (could be signs of high blood sugar).
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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 child's doctor about the following:

Any allergies your child may have to this medication, its components, or other substances, including foods and drugs. Please describe the allergic reaction and its symptoms.
If your child has a history of breathing problems, such as sleep apnea, or other health conditions like:
+ Cancer or 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 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 your child's other medications and health conditions. Never start, stop, or adjust the dosage of any medication without consulting your child's 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 or worsening diabetes, while taking this drug. To monitor this, follow the doctor's instructions for checking your child's blood sugar levels. Additionally, adhere to the recommended schedule for your child's blood work and eye exams as advised by their doctor.

This medication may interfere with certain laboratory tests. Be sure to notify all of your child's healthcare providers and laboratory personnel that your child is taking this drug.

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

Do not share this medication, needles, or syringes with anyone, even if the needle has been changed, as this can lead to the transmission of infections, including those that may not be immediately apparent.

Be aware that this medication can cause an excess of fluid in the body, potentially leading to heart failure. If your child exhibits symptoms such as shortness of breath, significant weight gain, or swelling in the arms or legs, contact their doctor immediately.

If your child has scoliosis (an abnormal curvature of the spine), discuss the potential risks with their doctor, as this medication may exacerbate the condition in children who are still growing.

For children with a history of cancer or tumors, consult with their doctor, as this medication may increase the risk of cancer or tumor growth. Additionally, the development of new tumors may be a concern for some patients.

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

If your child is pregnant or breastfeeding, it is crucial to discuss the benefits and risks of this medication with their doctor, as it may affect both your child and the baby.
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Overdose Information

Overdose Symptoms:

  • Acute overdose: Hypoglycemia (low blood sugar) initially, followed by hyperglycemia (high blood sugar).
  • Chronic overdose: Signs and symptoms of gigantism (in children) or acromegaly (in adults), such as overgrowth of hands and feet, joint pain, 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 involves supportive care, monitoring blood glucose levels, and addressing any symptoms of overgrowth in chronic cases.

Drug Interactions

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Major Interactions

  • Glucocorticoids (may inhibit growth-promoting effects of lonapegsomatropin; monitor growth and adjust dose if necessary)
  • Thyroid hormones (may alter response to growth hormone; monitor thyroid function and adjust thyroid hormone dose as needed)
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Moderate Interactions

  • Insulin and/or other antidiabetic agents (growth hormone may decrease insulin sensitivity, requiring dose adjustments of antidiabetic agents)
  • CYP450 metabolized drugs (growth hormone may alter the activity of CYP450 enzymes, particularly CYP3A4, potentially affecting metabolism of co-administered drugs)

Monitoring

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Baseline Monitoring

IGF-1 and IGFBP-3 levels

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

Timing: Prior to initiation of therapy

Thyroid function tests (TSH, Free T4)

Rationale: Hypothyroidism can interfere with response to growth hormone therapy; correct before starting.

Timing: Prior to initiation of therapy

Fasting glucose and HbA1c

Rationale: To assess baseline glucose metabolism; growth hormone can affect insulin sensitivity.

Timing: Prior to initiation of therapy

Bone age

Rationale: To assess skeletal maturity and growth potential.

Timing: Prior to initiation of therapy

Fundoscopic examination

Rationale: To rule out pre-existing papilledema, which can be exacerbated by intracranial hypertension.

Timing: Prior to initiation of therapy

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Routine Monitoring

IGF-1 levels

Frequency: Every 4-6 weeks initially, then every 3-6 months or as clinically indicated

Target: Age- and sex-adjusted normal range (0 to +2 SDS)

Action Threshold: If IGF-1 levels are consistently above +2 SDS, consider dose reduction. If consistently below -2 SDS, consider dose increase.

Growth velocity (height)

Frequency: Every 3-6 months

Target: Increased growth velocity appropriate for age

Action Threshold: Lack of expected growth response may indicate need for dose adjustment or evaluation for other causes.

Thyroid function tests (TSH, Free T4)

Frequency: Every 6-12 months or as clinically indicated

Target: Normal range

Action Threshold: Treat hypothyroidism if present, as it can impair growth response.

Fasting glucose and HbA1c

Frequency: Annually or as clinically indicated

Target: Normal range

Action Threshold: Monitor for glucose intolerance or new-onset diabetes; adjust antidiabetic therapy if needed.

Scoliosis assessment

Frequency: Annually or as clinically indicated

Target: No progression

Action Threshold: Monitor for progression of pre-existing scoliosis.

Fundoscopic examination

Frequency: Periodically, especially if symptoms of intracranial hypertension (e.g., severe headache, visual disturbances) occur.

Target: No papilledema

Action Threshold: Discontinue therapy if papilledema is confirmed.

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Symptom Monitoring

  • Severe or recurrent headache
  • Visual disturbances (e.g., blurred vision, double vision)
  • Nausea and vomiting
  • Limping or hip/knee pain (suggestive of slipped capital femoral epiphysis)
  • Progression of scoliosis
  • Changes in skin lesions (e.g., pigmented nevi)
  • Signs of allergic reaction (rash, itching, swelling, difficulty breathing)
  • Injection site reactions (pain, redness, swelling)

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 shown evidence of harm to the fetus. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Trimester-Specific Risks:

First Trimester: Limited human data; animal studies suggest no clear risk.
Second Trimester: Limited human data; animal studies suggest no clear risk.
Third Trimester: Limited human data; animal studies suggest no clear risk.
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Lactation

It is not known whether lonapegsomatropin is excreted in human milk. Many drugs are excreted in human milk, and there is a potential for serious adverse reactions in breastfed infants from lonapegsomatropin. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for Skytrofa and any potential adverse effects on the breastfed infant from Skytrofa or from the underlying maternal condition. Caution should be exercised when Skytrofa is administered to a nursing mother.

Infant Risk: Unknown; potential for adverse effects.
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Pediatric Use

Skytrofa is indicated for the treatment of pediatric patients 1 year and older with growth hormone deficiency (GHD). Safety and effectiveness in pediatric patients less than 1 year of age have not been established.

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Geriatric Use

The safety and effectiveness of Skytrofa in geriatric patients have not been established. Skytrofa is not indicated for use in adults.

Clinical Information

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Clinical Pearls

  • Skytrofa offers a once-weekly dosing regimen, which can significantly improve adherence compared to daily growth hormone injections.
  • Dosing is weight-based and should be individualized based on IGF-1 levels and growth response.
  • Patients and caregivers must be thoroughly trained on proper subcutaneous injection technique and auto-injector use.
  • Regular monitoring of IGF-1, growth velocity, thyroid function, and glucose metabolism is crucial.
  • Educate patients/caregivers on signs and symptoms of potential serious adverse effects, such as intracranial hypertension, slipped capital femoral epiphysis, and progression of scoliosis, and when to seek medical attention.
  • Ensure patients understand the importance of rotating injection sites to prevent lipoatrophy or lipohypertrophy.
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Alternative Therapies

  • Other somatropin (recombinant human growth hormone) products for daily subcutaneous injection (e.g., Norditropin, Genotropin, Humatrope, Saizen, Omnitrope, Zomacton, Nutropin)
  • Somapacitan-beco (Sogroya) - another long-acting growth hormone, approved for adult GHD, not pediatric 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, often subject to step therapy and quantity limits)
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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 come with an additional patient information leaflet; if you have any 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 call the 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.