Recombinant IGF-1 (Mecasermin)
Recombinant IGF-1 (Mecasermin)
Mecasermin is a biosynthetic human insulin-like growth factor-1 (IGF-1) produced by recombinant DNA technology. It is structurally identical to endogenous human IGF-1 and is critical for cellular growth and differentiation.
Key Points
- Molecular Weight: 7.6 kDa
- Half-life: 20-24 hours when bound to IGFBP-3
- Route: Subcutaneous injection
- Frequency: Twice daily administration
- Brand Name: Increlex®
Mechanism of Action
- Direct Growth Effects:
- Binds to IGF-1 receptors on target tissues
- Stimulates cellular proliferation
- Promotes cell differentiation
- Enhances protein synthesis
- Metabolic Effects:
- Increases glucose uptake
- Enhances insulin sensitivity
- Promotes amino acid transport
- Supports lipid metabolism
- Tissue-Specific Actions:
- Promotes longitudinal bone growth
- Enhances skeletal muscle development
- Supports cartilage formation
- Influences organ growth and development
Clinical Indications
FDA-Approved Indications:
- Primary IGF-1 Deficiency
- Severe Primary IGF-1 Deficiency (SPIGFD)
- Growth Hormone Gene Deletion
- GH Receptor Mutations (Laron Syndrome)
- GH Receptor Post-signaling Defects
- Diagnostic Criteria for SPIGFD:
- Height SDS ≤ -3.0
- Basal IGF-1 SDS ≤ -3.0
- Normal or elevated GH levels
- Exclusion of secondary causes
Dosing & Administration
Standard Dosing Protocol:
- Initial Dose:
- 0.04-0.08 mg/kg twice daily
- Maximum single dose: 0.12 mg/kg
- Dose Titration:
- May increase by 0.04 mg/kg per dose
- Minimum interval between adjustments: 1 week
- Maximum dose: 0.12 mg/kg given twice daily
Administration Guidelines:
- Give within 20 minutes of a meal or snack
- Rotate injection sites
- Never exceed maximum single dose
- Store under refrigeration (2-8°C)
- Discard opened vials after 30 days
Monitoring & Safety
Required Monitoring:
- Growth Parameters:
- Height and weight every 3-6 months
- Growth velocity calculation
- Annual bone age assessment
- Laboratory Monitoring:
- IGF-1 levels
- Glucose levels
- HbA1c
- Thyroid function
- Clinical Monitoring:
- Fundoscopic examination
- Tonsil examination
- Cardiac evaluation if symptomatic
Adverse Effects:
- Common:
- Hypoglycemia
- Injection site reactions
- Tonsillar/adenoidal hypertrophy
- Headache
- Vomiting and nausea
- Serious:
- Intracranial hypertension
- Allergic reactions
- Lymphoid tissue hypertrophy
- Cardiac changes
Contraindications & Precautions
Absolute Contraindications:
- Active or suspected neoplasia
- Closed epiphyses
- Allergy to mecasermin
- Chronic illness requiring nutritional failure
Special Precautions:
- Risk Factors:
- History of hypoglycemia
- History of neoplasia
- Scoliosis
- Obesity
- At-Risk Populations:
- Young children
- Patients with diabetes
- Patients with sleep apnea
- Those with compromised nutrition
Drug Interactions:
- Insulin and oral hypoglycemics
- Glucocorticoids
- Thyroid hormones
- Sex steroids
