Somatropin - Nutropin AQ (Genentech) - Complete Research Paper
1. Summary
Nutropin AQ is a recombinant human growth hormone (rhGH, somatropin) manufactured by Genentech, Inc., a member of the Roche Group. Originally approved in 1987, Nutropin was among the pioneering recombinant growth hormone products. Nutropin AQ is distinguished by its liquid formulation (no reconstitution required) and unique indication for chronic kidney disease (CKD)—an indication not shared by most competitors.
IMPORTANT UPDATE: On December 31, 2024, Genentech discontinued manufacturing Nutropin AQ NuSpin in the United States. As of January 1, 2025, most insurance plans no longer cover Nutropin AQ. Patients should consult healthcare providers about alternative growth hormone therapies.
FDA Approval: 1987 (Initial U.S. Approval) Manufacturer: Genentech, Inc. (South San Francisco, CA), a Member of the Roche Group NDA: 020522
Key Clinical Features:
- Drug class: Recombinant human growth hormone (somatropin)
- Molecular weight: ~22,125 daltons (191 amino acids)
- Administration: Subcutaneous injection
- Half-life: ~2.3 hours (SC), ~20 minutes (IV)
- Bioavailability: 81 ± 20%
- Unique feature: Ready-to-use liquid formulation; CKD indication
Primary Advantage: Nutropin AQ's liquid formulation eliminates reconstitution steps, and its approval for chronic kidney disease (CKD) makes it a unique option for pediatric patients with renal failure awaiting transplant. The NuSpin injection device offered an easy-to-use prefilled option (prior to discontinuation).
2. Mechanism of Action
Nutropin AQ functions identically to natural pituitary-derived human growth hormone.
Primary Mechanism:
- GH Receptor Binding: Somatropin binds to GHR on target cells (liver, muscle, bone, adipose)
- JAK2-STAT5 Activation: Receptor dimerization triggers intracellular signaling cascade
- Gene Transcription: Growth-related gene expression induced
- IGF-I Production: Hepatic IGF-I synthesis stimulated (primary mediator of growth effects)
Direct Effects:
- Skeletal growth at epiphyseal plates (pediatric)
- Muscle protein synthesis enhancement
- Bone metabolism stimulation
- Organ growth regulation
Metabolic Effects: | System | Effect | |---
Goal Relevance:
- Help my child grow taller despite their chronic kidney disease.
- Support my child's growth when they have Turner Syndrome.
- Improve my child's height when they have idiopathic short stature.
- Manage my adult growth hormone deficiency to boost my energy levels.
- Enhance my child's growth potential while waiting for a kidney transplant.
- Increase my muscle mass and strength as an adult with growth hormone deficiency.
- Support my child's growth when they have growth hormone deficiency.
-----|--------| | Protein | Increased synthesis, nitrogen retention, positive nitrogen balance | | Lipid | Enhanced lipolysis, reduced visceral fat mass | | Carbohydrate | Insulin resistance (dose-dependent), counter-regulatory to insulin | | Mineral | Increased calcium absorption, enhanced bone mineral density |
Renal Effects (Relevant to CKD Indication):
- Growth failure in CKD is multifactorial (uremic toxins, acidosis, poor nutrition)
- Somatropin overcomes GH resistance seen in uremia
- IGF-I levels increase despite underlying kidney disease
- Growth velocity improves with maintained renal function
3. FDA-Approved Indications
Nutropin AQ has a unique indication profile including chronic kidney disease.
Pediatric Indications:
| Indication | Notes |
|---|---|
| Growth Hormone Deficiency (GHD) | Standard indication for inadequate endogenous GH secretion |
| Idiopathic Short Stature (ISS) | Height SDS ≤ -2.25, unlikely to reach normal adult height |
| Turner Syndrome (TS) | Chromosomal abnormality causing short stature in females |
| Chronic Kidney Disease (CKD) | Growth failure up to time of renal transplantation (UNIQUE) |
Adult Indication:
| Indication | Details |
|---|---|
| Adult GHD | Childhood-onset or adult-onset GHD meeting diagnostic criteria |
Unique Feature - CKD Indication: Nutropin AQ is one of the few somatropin products FDA-approved specifically for growth failure in pediatric patients with chronic kidney disease. This indication applies up to the time of renal transplantation, recognizing that:
- Uremia causes GH resistance
- Growth velocity is severely impaired in CKD children
- Treatment can improve final adult height outcomes
Indications NOT Approved:
- Prader-Willi syndrome
- Small for Gestational Age (SGA)
- SHOX deficiency
- Noonan syndrome
4. Dosing and Administration
General Principles:
- Subcutaneous administration only
- Rotate injection sites (thigh, abdomen, buttocks, upper arm)
- Ready-to-use liquid—no reconstitution required
- Daily injections recommended
Pediatric Dosing by Indication:
| Indication | Weekly Dose | Notes |
|---|---|---|
| GHD | Up to 0.3 mg/kg/week | Divided into daily doses |
| ISS | Up to 0.3 mg/kg/week | Individualized based on response |
| Turner Syndrome | Up to 0.375 mg/kg/week | Higher doses often needed |
| CKD | Up to 0.35 mg/kg/week (0.05 mg/kg/day) | Continue until transplant or epiphyseal closure |
Adult GHD Dosing:
| Approach | Details |
|---|---|
| Weight-Based | Start: ≤0.006 mg/kg/day; Max (≤35 years): 0.025 mg/kg/day; Max (>35 years): 0.0125 mg/kg/day |
| Non-Weight-Based (Preferred) | Start: 0.2 mg/day (range 0.15-0.30 mg/day); Increase 0.1-0.2 mg/day every 1-2 months |
Age-Based Maximum (Adults):
- Patients ≤35 years: Up to 0.025 mg/kg/day
- Patients >35 years: Up to 0.0125 mg/kg/day
Special Considerations:
- Elderly: Lower starting dose, smaller increments
- Obese: Non-weight-based dosing preferred
- CKD: Continue therapy through dialysis if growth potential remains
Product Presentations (Prior to 2025 Discontinuation):
| Formulation | Strength | Device Color |
|---|---|---|
| Pen Cartridge | 10 mg/2 mL | Yellow band |
| Pen Cartridge | 20 mg/2 mL | Purple band |
| NuSpin | 5 mg/2 mL | Clear device |
| NuSpin | 10 mg/2 mL | Green device |
| NuSpin | 20 mg/2 mL | Blue device |
5. Pharmacokinetics
Absorption:
- Route: Subcutaneous injection
- Bioavailability: 81 ± 20% (compared to IV)
- Tmax: 3.9 hours
- Cmax: 71.1 µg/L (at 0.1 mg/kg dose)
- AUC: 677 µg·hr/L
Distribution:
- Distributes to liver, kidney, muscle, bone, target tissues
- Volume of distribution similar to other somatropin products
Metabolism:
- Classical protein catabolism
- Primary sites: Liver and kidneys
- No CYP450 enzyme involvement
- Proteolytic degradation to amino acid constituents
Elimination:
- Half-life (IV bolus): ~20 minutes
- Half-life (SC): ~2.3 hours (CV 18%)
- Clearance (SC): 150 mL/(hr·kg) [CL/Fsc]
- Clearance (IV): 116-174 mL/h/kg
Special Populations:
| Population | Effect on PK |
|---|---|
| Pediatric (7-11 years) | Clearance reduced ~21-22% vs. healthy adults |
| CKD/ESRD | Decreased clearance compared to normal |
| Hepatic impairment | Reduced clearance |
| Gender | No significant differences |
| Elderly | May be more sensitive; dose adjustment needed |
6. Side Effects and Adverse Reactions
Common Adverse Events:
Injection Site Reactions:
- Pain
- Redness
- Swelling
- Most frequent adverse event (0.3% in ISS studies)
Fluid Retention (Adults):
- Peripheral edema
- Arthralgia
- Joint disorders
- Carpal tunnel syndrome
- Paresthesia
Metabolic Effects:
- Glucose intolerance
- New onset or worsening diabetes
- Hypothyroidism
Clinical Trial Data (ISS): In 8,018 ISS patients, adverse events occurred in only 1.3% of subjects, demonstrating favorable tolerability.
Serious Adverse Reactions:
Neoplasm Concerns:
- Increased risk of secondary neoplasms in childhood cancer survivors
- Meningiomas particularly increased in patients with brain/head radiation history
7. Drug Interactions
| Interacting Drug | Effect | Management |
|---|---|---|
| Glucocorticoids | May attenuate growth-promoting effects | Monitor growth response; adjust GH dose if needed |
| 11β-HSD-1 Inhibitors | May unmask hypoadrenalism | May require glucocorticoid initiation/adjustment |
| Oral Estrogen | Reduces IGF-I response | Larger somatropin doses may be required in women |
| Insulin/Antidiabetics | Somatropin causes insulin resistance | Monitor glucose; may need to increase diabetes medication doses |
| CYP450 Substrates | Somatropin may increase clearance | Monitor drugs with narrow therapeutic index |
| Thyroid Hormones | May unmask or worsen hypothyroidism | Monitor thyroid function; adjust levothyroxine |
8. Contraindications
Absolute Contraindications:
| Condition | Rationale |
|---|---|
| Acute critical illness | Increased mortality (surgery, trauma, respiratory failure) |
| PWS with severe obesity or respiratory impairment | Reports of sudden death |
| Active malignancy | May stimulate tumor growth |
| Closed epiphyses (for growth indications) | No growth benefit possible |
| Hypersensitivity to somatropin or excipients | Anaphylaxis risk |
| Active proliferative or severe non-proliferative diabetic retinopathy | May worsen retinopathy |
Relative Contraindications/Precautions:
- History of malignancy (especially childhood cancer)
- Pre-existing diabetes or impaired glucose tolerance
- Intracranial hypertension
- Scoliosis
- Turner syndrome (increased fluid retention risk)
9. Special Populations
Pediatric Patients:
- Safety and efficacy established for GHD, ISS, Turner syndrome, and CKD
- Monitor for SCFE (hip/knee pain, limp)
- Evaluate for intracranial hypertension
- CKD patients: Continue therapy through dialysis
Geriatric Patients:
- May be more sensitive to somatropin action
- More prone to adverse effects
- Use lower starting dose
- Use smaller dose increments
Pregnancy:
- Category B (under prior classification)
- Use only if clearly needed
- No adequate controlled studies
Lactation:
- Unknown if excreted in human milk
- Caution advised
- Consider benefit vs. risk
Chronic Kidney Disease:
- FDA-approved indication for pediatric CKD patients
- Decreased clearance expected
- Continue until renal transplantation or epiphyseal closure
- Monitor carefully during dialysis
Hepatic Impairment:
- Reduced clearance expected
- Use with caution
- May require dose adjustment
10. Monitoring Parameters
Baseline Evaluation:
- Height and weight
- Bone age (pediatric)
- IGF-I level
- Thyroid function (free T4, TSH)
- Fasting glucose and HbA1c
- Fundoscopic examination
- Scoliosis assessment (pediatric)
- Renal function (CKD patients)
Ongoing Monitoring:
| Parameter | Frequency | Notes |
|---|---|---|
| Height velocity | Every 3-6 months (pediatric) | Primary efficacy endpoint |
| IGF-I | After dose changes; every 6-12 months | Target age-appropriate range |
| Thyroid function | Every 6-12 months | May unmask hypothyroidism |
| Fasting glucose/HbA1c | Every 6-12 months | Monitor for diabetes |
| Hip/knee exam | Each visit (pediatric) | Screen for SCFE |
| Fundoscopic exam | As indicated | If headache, visual changes |
| Scoliosis assessment | Each visit (pediatric) | May progress during growth |
| Renal function | Per nephrology schedule (CKD) | Monitor disease progression |
Intracranial Hypertension Monitoring:
- Can develop within 8 weeks of treatment initiation
- Watch for papilledema, visual changes, headache, nausea
11. Cost and Availability
IMPORTANT: PRODUCT DISCONTINUATION
As of December 31, 2024, Genentech discontinued manufacturing Nutropin AQ NuSpin in the United States. Most insurance plans stopped covering Nutropin AQ effective January 1, 2025. Patients should work with healthcare providers to transition to alternative growth hormone therapies.
Historical Pricing (Prior to Discontinuation):
| Formulation | Approximate Cost |
|---|---|
| 5 mg/2 mL NuSpin | ~$670 |
| 10 mg/2 mL NuSpin | ~$1,200-1,400 |
| 20 mg/2 mL solution | ~$2,464+ |
Patient Assistance Programs (While Available):
Nutropin GPS Co-Pay Card Program: Phone: 1-866-688-7674
- Out-of-pocket reduced to as low as $5/prescription
- Maximum: $500/month or $5,000/year
- Requires insurance coverage
Genentech Patient Foundation: Phone: 1-888-941-3331 (Monday-Friday, 6 AM - 5 PM PT)
- Free medication for uninsured patients
- Financial hardship qualification
- Coverage denial assistance
Genentech Access to Care Foundation (GATCF):
- For uninsured patients
- For patients denied insurance coverage
- Free medication program
Transition Considerations: Patients discontinuing Nutropin AQ should consider:
- Norditropin (room temperature stability)
- Genotropin (MiniQuick option)
- Omnitrope (lower cost)
- Humatrope (SHOX indication if needed)
12. Clinical Evidence Summary
Pediatric GHD Efficacy:
- Significant improvement in height velocity
- Catch-up growth demonstrated in controlled trials
- Long-term height gains comparable to other somatropin products
Idiopathic Short Stature:
- Height velocity increases of 3-4 cm/year above baseline
- Improvement in predicted adult height
- Favorable safety profile (1.3% adverse event rate in 8,018 patients)
Turner Syndrome:
- Documented improvement in final adult height
- Higher doses often required (up to 0.375 mg/kg/week)
- Consistent with other somatropin product efficacy
Chronic Kidney Disease (Unique Data):
- Significant improvement in height velocity in CKD children
- Growth maintained during dialysis period
- Benefits persist up to time of transplant
- IGF-I levels increase despite uremic state
Adult GHD:
- Improved body composition (reduced fat mass, increased lean mass)
- Enhanced quality of life
- Improved bone mineral density
- Favorable cardiovascular risk marker changes
13. Comparison with Alternatives
| Product | Manufacturer | Unique Features | CKD Indication |
|---|---|---|---|
| Nutropin AQ | Genentech | Liquid formulation, NuSpin | YES |
| Genotropin | Pfizer | MiniQuick single-use, broadest indications | No |
| Humatrope | Eli Lilly | SHOX deficiency | No |
| Norditropin | Novo Nordisk | Room temp 3 weeks, FlexPro | No |
| Omnitrope | Sandoz | Lower cost biosimilar | No |
| Saizen | EMD Serono | easypod connectivity | No |
Historical Advantages of Nutropin AQ:
- CKD indication: Unique FDA approval for renal failure patients
- Liquid formulation: No reconstitution needed
- NuSpin device: Easy-to-use prefilled pen
- Multiple concentrations: 5, 10, and 20 mg options
Post-Discontinuation Considerations: For CKD patients requiring growth hormone, consult with pediatric nephrologist regarding:
- Off-label use of other somatropin products
- Individual patient factors affecting product selection
- Insurance coverage for alternative therapies
14. Storage and Handling
Liquid Formulation (Pen Cartridge/NuSpin):
- Refrigerate at 2-8°C (36-46°F)
- Do NOT freeze
- Protect from light
- After first use: Refrigerate; use within 28 days
- Do not store with needle attached
Important Handling Notes:
- Inspect for clarity before use
- Do not inject if solution appears cloudy or hazy
- Discard if particulate matter observed
- Return to refrigerator immediately after use
Disposal:
- Follow local regulations for pharmaceutical waste
- Use sharps container for needles
- Return unused medication to pharmacy
15. References
-
Nutropin AQ Prescribing Information. Genentech, Inc. Available at: https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=139d2038-e6a9-4ab1-ab00-aa7d8aa8df5f
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FDA Drug Approval Package: Nutropin AQ NDA #020522. Available at: https://www.accessdata.fda.gov/drugsatfda_docs/nda/
-
Genentech. Nutropin AQ Patient Information. Available at: https://www.gene.com/patients/medicines/nutropin-aq
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Drugs.com. Nutropin AQ Package Insert / Prescribing Information. Available at: https://www.drugs.com/pro/nutropin-aq.html
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GoodRx. Nutropin AQ 2025 Prices, Coupons & Savings Tips. Available at: https://www.goodrx.com/nutropin-aq
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UnitedHealthcare. Nutropin AQ NuSpin Coverage Ending 2025. Available at: https://www.uhcprovider.com/en/resource-library/news/2024/nutropin-aq-nuspin-coverage-ending.html
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Genentech Patient Foundation. Available at: https://www.gene.com/patients/patient-foundation
-
FDA. Nutropin Depot Approval Package (Historical). Available at: https://www.accessdata.fda.gov/drugsatfda_docs/nda/99/21075_Nutropin.cfm
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European Medicines Agency. NutropinAq Product Information. Available at: https://www.ema.europa.eu/en/documents/product-information/nutropinaq-epar-product-information_en.pdf
-
RxList. Nutropin AQ Drug Information. Available at: https://www.rxlist.com/nutropin-aq-drug.htm
Document compiled from FDA prescribing information, manufacturer resources, and clinical literature. Last updated: December 2024.
Note: This document reflects information available at the time of writing. The discontinuation of Nutropin AQ NuSpin in December 2024 significantly impacts product availability in the United States.
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